153 articles trouvés pour ce sujet.
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3.1 miles in 4 minutes |
2021-06-21 |
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Jean pose la question :
I am a school bus driver. My route directions and time schedule have me traveling
3.1 miles in 4 minutes. How fast do "they" expect me to drive to accomplish this?
Thank You
Penny Nom lui répond. |
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Velocity and acceleration |
2021-01-09 |
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yen pose la question :
The motion of a stone projected upward is given by the relation s=112t - 16t^2.
What are the values of velocity and acceleration when t=3 sec?
Penny Nom lui répond. |
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The angular speed of a wheel |
2020-09-03 |
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Catrina pose la question :
A car is moving at a rate of 75 miles per hour, and the diameter of its wheels is 2.6 in. Find the angular speed of the wheels in radians per minute.
Penny Nom lui répond. |
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A word problem with no algebra |
2020-08-11 |
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Julie pose la question :
At 3pm, Bruce headed north at 30 km/hr. 2 hours later, Lucy headed south at 40 km/hr. At what time will they be 340 km apart
Penny Nom lui répond. |
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The flight of a football |
2020-05-06 |
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Michael pose la question :
Football is thrown from a 10-yard line. It reaches its highest height of 20 yards. It lands on the 50-yard line after 2 seconds. What is the equation of the parabola that models this throw? I really need help as I've been on this for the longest amount of time.
Penny Nom lui répond. |
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10 miles in 2 minutes |
2019-12-20 |
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james pose la question :
how fast would you be traveling to go 10 miles in 2 minutes?
Harley Weston lui répond. |
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Distance traveled |
2019-07-03 |
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J pose la question :
If a fly flies at 15 feet per a second between two walls closing in upon themselves. Wall A is moving to the right at 3 feet a second and wall B is moving to the left at 15 feet a minute, how far will the fly fly before the walls touch?
Penny Nom lui répond. |
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A car drives over a cliff |
2019-06-06 |
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Victor pose la question :
A car was going 90 mph towards 90foot drop. What would the distance would the car travel horizontally ,from the cliff edge?
Penny Nom lui répond. |
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Angular velocity |
2018-12-05 |
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Kolade pose la question :
Krusty the Clown and Sideshow Bob have covered themselves in velcro, and shot themselves out of a large
cannon so that they stick to a huge rotating velcro wheel (don’t try this at home). As shown in Figure 1(a),
Krusty is now stuck to a point 3.00 m from the center of the wheel while Bob is stuck to another point 5.00 m
from the center. The wheel is rotating counterclockwise at 10.0 rpm. Conveniently a set of axes is suspended
just in front the wheel (Krusty asked for axes, like the ones you would use to chop wood, so that he and Bob
could chase each other with them in the usual wholesome entertainment he is known for. Unfortunately, the
set designer misunderstood.) The axes do not rotate with the wheel.
(a) Find Krusty’s and Bob’s angular velocities, in radians per second.
Penny Nom lui répond. |
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Angular speed |
2018-10-18 |
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Akidima pose la question :
A bicycle wheel rotates uniformly through 2.0 revolutions in 4.0 seconds .
What is the average angular speed of the wheel
Penny Nom lui répond. |
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Velocity |
2018-09-14 |
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Adrian pose la question :
If Jill was traveling at 300 miles in 4 hours due South what was his velocity in miles per second.
Penny Nom lui répond. |
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An egg falls from rest |
2018-05-10 |
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Amy pose la question :
An egg falls from rest a distance of 75cm to the floor.
Neglecting air resistance, at what speed does it hit the floor?
Penny Nom lui répond. |
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Throwing a football |
2018-04-26 |
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Abby pose la question :
Daring Danny's threw a football at an angle of 40 degrees to the horizontal. The football hit the ground at 36 feet. Danny is 5 feet 1 inch tall. Find the initial velocity
I have been trying to figure this problem out for forever! Please help! I am really confused because I don't know time either and you are supposed to find that as well as velocity.
Penny Nom lui répond. |
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A penny is thrown from the top of a building |
2018-03-16 |
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Zoraida pose la question :
A penny is thrown from the top of a 26.7-meter building and hits the ground 3.39 seconds after it was thrown. The penny reached its maximum height above the ground 0.89 seconds after it was thrown.
a. Define a quadratic function, h, that expresses the height of the penny above the ground (measured in meters) as a function of the number of seconds elapsed since the penny was thrown, t.
b. What is the maximum height of the penny above the ground?
Penny Nom lui répond. |
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A cyclist reduces his speed |
2018-02-27 |
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Katherine pose la question :
Suppose the winner had reduced his average cycling rate by .1 mile per hour.
By how much would his time have changed?
(the cyclist's rate is 23.66 miles per hour and the answer to the question before this
one was that he cycled 2,292 miles in 96.87 hours)
Penny Nom lui répond. |
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Speed in kilometers per hour |
2017-12-21 |
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Cody pose la question :
if a train travels 400 meters in 30 seconds how many kilometers per hr is it traveling
Penny Nom lui répond. |
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How many miles did he drive in one hour? |
2017-11-21 |
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Ava pose la question :
Graham drove 42 1/3 Miles in 1 1/3 hours. How many miles did he drive in one hour?
Penny Nom lui répond. |
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Walking up and down a hill |
2017-09-19 |
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Justina pose la question :
At 2:20 p.m. Jack is at the top of the hill and starts walking down at the exact same time that Jill, who is at the bottom of the hill, starts walking up. If they maintain the uphill speed of 2mph and downhill speed of 4mph and the distance from the bottom to the top of the hill is 1.5 mi, at what time will Jack and Jill meet?
Penny Nom lui répond. |
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Up a hill and down again |
2017-09-17 |
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justina pose la question :
Jack and Jill travel up a hill at a speed of 2mi/h.they travel back down the hill at a speed of 4mi/h.what is their average speed for the entire trip? express your answer as a mixed number
Penny Nom lui répond. |
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A car on a rough road and a concrete road |
2017-08-27 |
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Ken pose la question :
A car is driven on a rough road at a speed of 25km and then on a concrete road with a speed of 70kph. The car has 5.5 hours to travel 225km. How long did the car travel on concrete road?
Penny Nom lui répond. |
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How fast am I travelling? |
2017-06-24 |
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corey pose la question :
if i travel 2 miles in 10 seconds, how fast am i travelling please
Penny Nom lui répond. |
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A man drives 48km in 45 minutes |
2017-06-03 |
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Jamal pose la question :
A man drives from Ibadan to Oyo a distance of 48km in 45 minutes. If he drives at 72km/h where the surface is good and 48km/h where the surface is bad. Find the number of kilometers of good surfaces
Penny Nom lui répond. |
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Initial velocity |
2017-05-23 |
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Annelle pose la question :
a body is thrown vertically downward from a height above the ground. determine the initial velocity and the height of the starting point if after 4 secs it reaches the ground with velocity of 68 m/s.
Penny Nom lui répond. |
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Yards per second to miles per hour |
2017-05-11 |
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Scott pose la question :
If a soccer ball travels 30 yards or roughly .017 miles in 2 seconds how fast was the ball going in mph?
Penny Nom lui répond. |
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Feet per second to miles per hour |
2017-01-27 |
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ron pose la question :
if a vehicle travels 50 feet in 2.5 seconds what is the speed in mph.
3600 sec in hour /5280 feet in a mile i get .68181818. how do i figure the 2.5
seconds. all the calculators I've used show 34 mph is that correct or am i forgetting the 2.5 second. please help.
Penny Nom lui répond. |
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Angular speed |
2017-01-21 |
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Kenzi pose la question :
A wheel of radius 14 inches is rotating 45°/sec. What is the linear speed in in/sec and the
angular speed in RPM? (Round your answers to three decimal places)
I already found the linear speed. I got 10.996 in/sec. I don't know how to find the angular
speed.
Penny Nom lui répond. |
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John and Max walk to meet each other |
2016-05-29 |
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abhay pose la question :
The speeds of John and Max are 30 km/h and 40 km/h.Initially Max is at a place L and John is at a place M. The distance between L and M is 650 km. John started his journey 3 hours earlier than Max to meet each other. If they meet each other at a place P somewhere between L and M, then the distance between P and M is?
Penny Nom lui répond. |
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At what time will Sara catch up with Jake? |
2016-05-07 |
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Laura pose la question :
At 11:00 a.m., Jake started driving along a highway at constant speed of 50 miles per hour. A quarter of an hour later, Sara started driving along the same highway in the same direction as Jake at the constant speed of 65 miles per hour. At what time will Sara catch up with Jake?
Penny Nom lui répond. |
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A 3 hour river cruise |
2016-05-06 |
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Jan pose la question :
A 3 hour river cruise goes 15km upstream and then back again.The river has a current speed of 2km/h.what is the boat's speed and how long was the upstream journey?
Penny Nom lui répond. |
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A road trip word problem |
2016-04-10 |
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Marc pose la question :
While on a road trip I imagined this random word problem. Suppose I start a trip of 75 miles. My initial speed is 75 miles per hour. After every mile traveled I decrease my speed by one mile per hour. After the first mile I decrease my speed to 74 miles per hour and so on for each subsequent mile traveled. How long will it take to complete the 75 mile journey?
Penny Nom lui répond. |
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Shooting a ball at a target |
2016-02-16 |
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Thys pose la question :
Hi
I have a problem with the formula that i use .(for programming)
I have looked all over the web to find a solution but no luck.
I have a cannon that shoots a ball at a target
I use this formula to calculate what my initial velocity must be to hit the target
at a angle of 30 degrees and a distance of 15m (the cannon and target position is known)
It works perfectly if both is at same height but if one is higher or lower it miss.
In an example I am working with the range is 30m, the angle is 45 degrees and the target is 10m higher than my position.
Please help
Formula = V0 = √RG / Sin(2α)
Harley Weston lui répond. |
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Speed and velocity |
2016-02-14 |
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kechi pose la question :
A boat sails south through Chesapeake Bay. It takes 10 hours to sail 110 kilometers. Describe the boat's motion. Calculate the boat's speed and velocity, showing the calculations. Explain how the boat's speed is different from its velocity
Penny Nom lui répond. |
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Travelling with and against he current |
2016-02-09 |
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Lloyd pose la question :
A boat travelled 210 miles downstream and back. The trip downstream took 10hrs, the trip back took 70hrs
1. what is the speed of the current?
2. what is the speed of the boat in still water?
Penny Nom lui répond. |
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Average rate for a return trip |
2015-03-14 |
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Michael pose la question :
Jeffrey drove to a town 25 miles away at an average speed of 50 miles per hour. The return trip along the same route took 20 minutes longer than the trip to town. Determine the average speed in miles per hour for Jeffrey's round trip.
Penny Nom lui répond. |
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Istanbul to Lagos |
2015-03-03 |
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Victor pose la question :
A plane flies from Istanbul to Lagos at 800km/h and then returns to Istanbul at 900km/h. The return trip takes 1 hour less than the flight to Lagos. What is the distance between Istanbul and Lagos?
Penny Nom lui répond. |
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Speed, distance and time |
2015-02-06 |
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Terry pose la question :
How many seconds would it take to travel 0.18 km at a speed of 130km per hour?
Penny Nom lui répond. |
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Two cars pass each other going in opposite directions |
2015-02-03 |
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Caroline pose la question :
Two cars pass each other going i opposite directions. One car is going 100 km/h and the other is going 80 km/h. How far apart will the two cars be after driving 45 minutes at these rates of speed?
Penny Nom lui répond. |
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A train from Vancouver to Whistler |
2015-02-02 |
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Tea pose la question :
Serena and Nina are taking a train from Vancouver to Whistler, a 160km trip. If the average speed is decreased by 16km/hr, the trip will be 1/2 hours longer. What is the average speed of the train?
Thanks :)
Penny Nom lui répond. |
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What is the speed of the boat in still water? |
2014-10-30 |
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Adam pose la question :
The current in a stream moves at a speed of 2 km/h. A boat travels 38 km upstream and 38 km downstream in a total time of 3 hr. What is the speed of the boat in still water?
Penny Nom lui répond. |
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Revolutions per minute |
2014-10-24 |
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Edward pose la question :
Hello; I have a 28.2 inch diameter tire; do not worry about engine RPM or gear ratios, please tell me what the RPM
of that tire is at 8 MPH and 64 MPH. Thank you.
Sincerely; Edward
Penny Nom lui répond. |
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Problem solving |
2014-09-08 |
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hubert pose la question :
a car left the house and travelled at an average speed of 60 kph.how many minutes will it take for the car to reach the school which is 8 km away from the house
Penny Nom lui répond. |
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A car passing a bus |
2014-08-24 |
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Athish pose la question :
the driver of the car is travelling at 36 km/hr and spots a bus 80 m ahead of him after 1 hr the bus is 120 m behind the car what is the speed of the bus
Penny Nom lui répond. |
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Distance, speed and time |
2014-08-13 |
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abdel pose la question :
Mac walked to a park from the college at 5 km/h. 10 minutes later, Steve started
riding his bike at 15 km/h to the same park to meet Mac. They arrive at the same
time at the park. How far is the park from the college?
Tyler Wood lui répond. |
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Angular speed |
2014-06-29 |
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andrea pose la question :
a wheel having a radius of 10cm rotates such that the linear speed at its rim is 30mls.
what is the angular speed of the wheel in rpm?
Penny Nom lui répond. |
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A speed word problem |
2014-02-24 |
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kiss pose la question :
Hank bicycles 5 km/h slower than Kelly. In the time that it takes Hank to bicycle 42 km, Kelly can bicycle 57 km. How fast does each bicyclist travel?
Penny Nom lui répond. |
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One train overtaking another |
2013-11-11 |
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kiran pose la question :
two trains of equal length are running in parallel tracks in the same direction with the speed of 60km/hr and 90km/hr respectively the latter completely crosses the former in 30 seconds the length of each train is in mtr
Penny Nom lui répond. |
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Distance as a function of acceleration |
2013-07-10 |
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Tom pose la question :
If you start at a stoplight and your acceleration is 16t - t^2, how far have you gone after 8 seconds?
Penny Nom lui répond. |
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Swimming upstream and downstream |
2013-02-15 |
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Kimberly pose la question :
a beaver swims down to its lodge 4 times faster than it swims upstream. how many times faster is its speed in still water than the speed of the stream?
Penny Nom lui répond. |
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Angular velocity |
2012-09-05 |
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Kyra pose la question :
A belt connects a pulley of radius 8cm to a pulley of radius 6cm. Each point on the belt is travelling at 24 cm/sec. Find the angular velocity of each pulley.
Penny Nom lui répond. |
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Two cars approach a right-angled intersection |
2012-04-10 |
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Michael pose la question :
Two cars approach a right-angled intersection, one traveling south a 40km/h and the other west at 70km/h.
When the faster car is 4km from the intersection and the other case if 3km from the intersection,
how fast is the distance between the car cars changing?
Penny Nom lui répond. |
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How long will it take lee to catch up with jodie? |
2012-03-21 |
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kirsten pose la question :
for example, if jodie is on the bus travelling at 10 m.p.h and lee is walking at 4 m.p.h how long will it take lee to catch up with jodie?? what is this mathematical name for this
Harley Weston lui répond. |
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Parametric equations 2 |
2012-02-25 |
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Kathy pose la question :
If the angle at time 0 is not 45 degrees how can you find the initial velocity? Ball thrown from height of 7 feet. Caught by receiver at height of 4 feet after traveling 90 feet down the field. Find initial velocity. You had a similar problem answered but the angle was 45 degrees so the cos and sin were equal and the equations were simpler to work with. Thank you!
Harley Weston lui répond. |
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Jack and Kate set off in their cars ... |
2012-02-13 |
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akiri pose la question :
Jack and Kate set off in their cars from the same point to travel the same journey. Jack has a start of eight minutes before Katie sets off. If Jack travels at 50mph and Katie travels at 75mph, how many miles will be travelled when the two cars are level?
Penny Nom lui répond. |
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There is a police officer in pursuit of suspect |
2012-02-01 |
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Jay pose la question :
There is a police officer in pursuit of suspect. They suspect is driving on a straight road traveling at 79 mph, the officer is 233 yds away, traveling at 92 mph, the suspects car 5 ft long and the officers car is 5.3 ft long, how long will it take to have the front of the officers car, equal to the front of the suspects car down to the tenth of a second.
Harley Weston lui répond. |
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Running 5 km |
2012-01-12 |
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Fayeann pose la question :
What amount of time will it take a person running 7 m/s to travel a distance of 5 km?
Penny Nom lui répond. |
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The average speed for the whole journey |
2011-10-30 |
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Shahzad pose la question :
a train travels 68 Km at an average speed of 51Km/h. It then travels another 20Km at an average speed of 40Km/h before reaching its destination. Calculate the average speed for the whole journey?
Penny Nom lui répond. |
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37 miles in 3 seconds |
2011-10-20 |
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Joyce pose la question :
Jake can travel 37 miles in 3 seconds,please calculate jake's rate of speed.(round to 2 decimal places)
Penny Nom lui répond. |
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What is the speed of the boat in still water? |
2011-10-07 |
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Hannah pose la question :
The speed of a stream is 3 mph. A boat travels 10 miles upstream in the same time it takes to travel 16 miles downstream. What is the speed of the boat in still water
Penny Nom lui répond. |
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Driving to meet Mary |
2011-08-24 |
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Denise pose la question :
mary leaves St Paul traveling 2000 miles @ 55 MPH; John leaves LA traveling 2000 miles @ 45 MPH how many miles will John had traveled to meet mary?
Penny Nom lui répond. |
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Two ships |
2011-04-05 |
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Gevork pose la question :
Ship A is sailing due south at 16 mph. At the same time, a second ship B, 32 miles south of A, is sailing due east at 12 mph.
(a) at what rate are they approaching or separating at the end of one hour?
(b) At what rate are they approaching or separating at the end of two hours?
(c) When do they cease to approach each other and how far apart are they at that instant.
Penny Nom lui répond. |
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Two boats |
2011-03-29 |
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Mamie pose la question :
Two speed boats leave the port of San Francisco traveling in opposite directions
at the same time.One boat travels 8 knots per hour faster than the other.After
one day's travel they are 1,920 nautical miles apart.What are the speeds of the
two boats.
Penny Nom lui répond. |
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What is its speed in miles per hour? |
2011-01-06 |
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Miriam pose la question :
An airliner travels 125miles in 15minutes. What is its speed in miles per hour?
Penny Nom lui répond. |
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80 miles in 40 minutes |
2010-12-08 |
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james pose la question :
i travel 8o miles in 40 minutes. how fast am i going in mph
Penny Nom lui répond. |
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Angular speed |
2010-12-03 |
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Julie pose la question :
If the angular speed of a circle is 360 degrees divided by the time it took to rotate,
how do I calculate ones that have greater rotations than the amount of time?
I mean, you calculate the angular speed of a merry-go-around that spins once every 5 seconds
by doing 360degrees/5 sec, but how do you calculate a merry-go-around that has 16 rotations every 4 seconds?
Penny Nom lui répond. |
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What is its speed in still air? |
2010-11-28 |
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Shelby pose la question :
An Airplane flies a certain distance in 3 hours going WITH a 40km/hr wind. It travels the same distance in 5 hours when going against the wind. What is it's speed and how long would it take to travel the same distance in still air? Distance = speed x time
Penny Nom lui répond. |
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What are the speeds of the boats? |
2010-10-21 |
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Adori pose la question :
Two boats leave the port of San Francisco traveling in opposite directions at the same time. One boat travels 8 knots per hour faster than
the other. After one day's travel they are 1920 nautical miles apart. What are the speeds of the boats?
Penny Nom lui répond. |
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John and Mary are 200 miles apart |
2010-10-20 |
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Sarah pose la question :
two people, john and mary, are 200 miles apart and leave at the same time to meet.
They are driving toward each other at constant rate on the same straight road.
John is traveling at 45 mph and Mary is traveling at 35 mph.
When they meet, how many miles will they be from john's house?
Penny Nom lui répond. |
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Two cars |
2010-09-30 |
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Amanda pose la question :
Two cars, 142 miles apart, start moving towards each other at the same
time. One is moving 3 times as fast as the other. If they meet 1.7 hrs
later, find the average speed of the slower car in miles per hour?
Penny Nom lui répond. |
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Two cars on a circular track |
2010-08-12 |
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david pose la question :
If two cars starts to drive at point 1 and go in a circle when will they meet?
(one cars speed is faster the other ) all I need is a formula
Tyler Wood lui répond. |
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Angular velocity |
2010-03-17 |
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Lindsay pose la question :
Determine the angular velocity, in radians per second, of a 14-inch car wheel, if the car is traveling at 60 miles per hour
Harley Weston lui répond. |
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At what rate are the people moving apart? |
2009-11-01 |
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saira pose la question :
A man starts walking north at 4 ft/s from a point P. 5 minutes later a woman starts walking south at 5 ft/s from a point 500 ft due east of P. At what rate are the people moving apart 15 minute after the woman starts walking ?
Harley Weston lui répond. |
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How fast am i going? |
2009-09-28 |
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ron pose la question :
how fast am i going if i drive 40 miles in 20 minutes...what is the formula for figuring this out.
Leeanne Boehm lui répond. |
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Initial Velocity of a Car Plunging Off a Cliff |
2009-06-07 |
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Mimi pose la question :
A car fails to take a sharp turn on a flat road and plunges off a cliff. The car lands 65m horizontally and 43m vertically from where it left the edge of the cliff. How fast was the car travelling?
Stephen La Rocque lui répond. |
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Two Boats |
2009-05-16 |
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Simon pose la question :
Two boats, one travelling towards the east and the other travelling towards the north, are 10 km apart afetr an hour. If the speed of one boat is 2 more than the speed of the other boat, what is the speed of the faster boat?
Stephen La Rocque lui répond. |
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Two airplanes are 300 miles apart |
2009-04-22 |
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afzalsultan pose la question :
Two airplanes are 300 miles apart and flying directly towards each other.One is flying at 200 miles per hour, and the other at 160 miles per hour.How long will it take for the two planes to meet
Robert Dawson lui répond. |
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Passing three cars |
2009-04-16 |
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Larry pose la question :
If 3 cars are going 50 mph, and a fourth car pass the first 3 cars in 200 feet, how fast is the fourth car going?
Stephen La Rocque lui répond. |
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How many miles per hour was it traveling? |
2009-04-04 |
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Regina pose la question :
a car traveled 16 miles in 30 minutes. How many miles per hour was it traveling?
Penny Nom lui répond. |
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The speed of a tire in revolutions per minute |
2009-03-28 |
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Jules pose la question :
Suppose that a tire on a car has an outer diameter of 2,5 feet. How many
revolutions per minute does that tire make when the car is travelling 60
miles per hour? (hint:first find the angular velocity in radians per minute.)
Harley Weston lui répond. |
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A 5 ounce object traveling at 60 mph |
2009-03-27 |
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James pose la question :
if a 5 ounce object traveling at 60 mph at 100 feet above the ground, how far will it travel forward before hitting the ground.
Robert Dawson lui répond. |
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A dead fly is stuck to a belt that passes over two pulleys |
2009-03-21 |
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Jules pose la question :
A dead fly is stuck to a belt that passes over two pulleys 6 inches and 8
inches in radius. Assuming no slippage,how fast is the fly moving when
the large pulley (8 inches) makes 21 revolutions per second ? How many
revolutions per second does the small pulley make ?
How long will it take the dead fly to travel 1 mile ?
Penny Nom lui répond. |
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A falling object |
2009-02-01 |
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Tamara pose la question :
We drop an object from rest (i.e. its initial spped is zero. It is falling freely toward the ground. What will be its speed after 5 seconds of falling?
Penny Nom lui répond. |
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What will be its speed after 10s? |
2009-02-01 |
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Tamara pose la question :
An object has an initial speed of 5 m/s and is accelerating with 2 m/s2 (m/s squared) acceleration. What will be its speed after 10s?
Penny Nom lui répond. |
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A belt drives a pulley |
2008-11-03 |
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Rebecca pose la question :
A point on a belt is moving at the rate of 30 ft/sec and the belt drives a pulley at the rate of 200 rpm. What is the radius of the pulley?
Penny Nom lui répond. |
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Linear and Angular Velocity |
2008-10-10 |
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Matthew pose la question :
The pedal and gear relationship of a bicycle is shown. The radii of the gears are r(sub1) = 5 cm and r(sub2)= 12 cm. The radius of the wheel is r(sub3) = 30 cm. How many rotations per minute of the pedal gear will produce a racing cyclist's speed of 60 km per hr.
For a diagram: http://bikepedalsgears.weebly.com/
Stephen La Rocque lui répond. |
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Angular & Linear Speed from a Sine Graph |
2008-08-19 |
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Kim pose la question :
Kim, a student:
I am given a graph with a wave. The amplitude is 5cm and the period is 4cm. I am suppose to find the angular speed. What I need to know is the formula for angular speed and how do I use these numbers to get the correct answer.
Janice Cotcher lui répond. |
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Time with Non-Uniform Motion |
2008-07-21 |
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jenina pose la question :
An unmarked police car, travelling a constant 95km/h, is passed by a speeder travelling 145km/h. precisely 1.00s after the speed passes, the policeman steps on the accelerator. If the police car’s acceleration is 2.00m/s², how much time elapses after the police car is passed until it overtakes the speeder (assumed moving at constant speed)?
Janice Cotcher lui répond. |
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The current in a river |
2008-06-12 |
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Joi pose la question :
To approximate the speed of the current of a river, a circular paddle wheel with radius 4 feet is lowered into the water. If the current causes the wheel to rotate at a speed of 10 revolutions per minute, what is the speed of the current? Express your answer in miles per hour.
Harley Weston lui répond. |
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A cat is walking on the tread of a tank |
2008-05-26 |
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Kathleen pose la question :
If a cat is walking on the tread of a tank travelling at 28kmh how fast does the cat have to walk to avoid falling under the tracks?
Janice Cotcher lui répond. |
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Throwing a ball on the moon |
2008-05-21 |
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leria pose la question :
equation for motion of moon is h=2.67t^2 + vt + s
equation for earth h=-16t + vt + s
Suppose you are on an outpost on the moon and Jan is back on Earth. Both people toss a ball from a height of 96 feet with an initial velocity of 16 feet per second. How much longer will your ball stay in motion on the moon than Jan's on the earth?
Math Central,
I'm having a difficult time understanding which numbers to plug into the formula.
Stephen La Rocque lui répond. |
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A crate is launched from an airplane |
2008-05-10 |
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Michelle pose la question :
A crate is launched from an airplane, 75 feet above the ocean, with an initial vertical velocity of 60 feet per second. How many seconds will it take for the crate to hit the water? Round to the nearest hundredth.
Harley Weston lui répond. |
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At what value of t is the maximum acceleration? |
2008-04-25 |
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Mary pose la question :
Velocity of a function (which is the first derivative of its position) is defined over the interval 0 to 12 using the following piecewise function: v(t)=-1 from 0 to 4, v(t)=x-5 from (4 to 8 and v(t)=-x+11 from (8 to 12. At what value of t is the maximum acceleration?
Stephen La Rocque lui répond. |
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What is the altitude of the plane? |
2008-04-23 |
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tiana pose la question :
If a plane is taking off and its climbing at 380 feet per minute at 205 MPH, what is the altitude of the plane after it traveled 115 miles?
Penny Nom lui répond. |
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Two points moving on a straight line |
2008-03-06 |
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laura pose la question :
Particle A travels at constant speed of 1.0ms-1 in straight line, passing particle B, at which time particle B beings traveling with constant acceleration of 0.2ms-2 until reaching Particle A.
What equations represent the displacement of particle A and particle B measure from the point they first pass?
How long does it take for particle B to catch up with particle A?
What is the speed of particle B when reaching particle A?
What distance have both particles traveled from where they first pass to where they meet again?
Calculate the displacement of both particle A and B at 2 second intervals between t=0s and t=12s?
Stephen La Rocque and Penny Nom lui répond. |
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Parametric equations |
2008-03-05 |
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kumi pose la question :
I have made a picture of a football pass 45 degrees with 30yds and height of 7ft and 4ft. But I am just stuck there. I have stared at the worksheet for soo long. I have no idea how to solve this, and I don't even know where this is going (I don't understand how parametric equations work). Can you help me with this problem?
1.The quarterback of a football team releases a pass at a height, h, of 7ft above the playing field, and the football is caught by a reciever at a height of 4ft, 30yds directly downfield. The pass is released at an angle of 45 degrees with the horizontal with an initial velocity of vo. The parametric equations for the position of the football at time t are given, in general, by x(t)=(vo cosθ)t and y=h+(vo sinθ)t-16t^2.
a. find the initial velocity of the football when it is released
b. write the specific set of parametric equations for the path of the football
c.use a graphing calculator to graph the path of the football and approximate its maximum height
d. find the time the reciever has to position himself after the quarterback releases the football
Harley Weston lui répond. |
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A ball bearing is placed on an inclined plane |
2008-02-15 |
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Leah pose la question :
A ball bearing is placed on an inclined plane and begins to roll.
The angle of elevation of the plane is x.
The distance (in meters) that the ball bearing rolls in t seconds is s(t) = 4.9(sin x)t^2.
What is the speed of the ball bearing,
and what value of x will produce the maximum speed at a particular time?
Penny Nom lui répond. |
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Two cars |
2007-09-17 |
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Lanie pose la question :
Two cars enter the Florida Turnpike at Commercial Boulevard at 8:00am, each heading for Wildwood. One car's average speed is 10 miles per hour more than the other's. The faster car arrives at Wildwood at 11:00 am, 1/2 hour before the other car. What is the average speed of each car? How far did each travel?
Stephen La Rocque lui répond. |
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How many miles per hour was I driving |
2007-09-11 |
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Gary pose la question :
How many miles per hour was I driving to go 37 miles in 13 minutes
Victoria West lui répond. |
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What angle does the tire turn in 60s? |
2007-06-04 |
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San pose la question :
An automobile, travelling at 80km/h, is towing a trailer. The wheels of the trailer
are 40cm in diameter. Through what angle does the tire turn in 60second?
Stephen La Rocque lui répond. |
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Angular velocity |
2007-05-01 |
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Bruce pose la question :
a tachometer of a Ford Explorer reads 2,100 rpm at 60 mph. Find the equivalent angular velocity in degrees per minute and radians per minute
Stephen La Rocque lui répond. |
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What is the speed of the boat? |
2007-04-22 |
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Sonja pose la question :
A boat on a river travels downstream between two points, 20 miles apart, in one hour. The return trip against the current takes 2 1/2 hours. What is the speed of the boat? The answer in the book says 14 mi/hr, but I don't understand how to figure it out. It must be very simple, but I'm stuck. Thank you so much for helping me out. This is a FANTASTIC website! -Sonja
Penny Nom lui répond. |
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The second derivative |
2007-04-14 |
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Gerry pose la question :
In mathematical context,what do you understand by the term "Second Derivative"
Penny Nom lui répond. |
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When will the rocket hit the ground? |
2007-04-05 |
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Megan pose la question :
A model rocket is launched at an upward velocity of 460feet per second off a platform that is 40 feet up from the ground. Use the formula h(t)= -16+vo+ho where vo is the initial velocity an ho is the initial height.
A.) Find the maximum hight of the rocket.
B.) How long does it take to reach the maximum height?
C.) When will the rocket hit the ground?
Stephen La Rocque lui répond. |
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Boat trigonometry |
2007-04-04 |
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Kimi pose la question :
Hi,
I have been working on the attached math problem for my college trig class for over a week. Every avenue I've tried seems to lead either to a dead end, an unreasonable answer, or extremely complicated computations. I was able to calculate the speed of the boat to 3.51 mph, but cannot figure out the measure of angle beta. Once I can figure that out, I can do the rest of the problem.
Thanks,
Kimi
Stephen La Rocque lui répond. |
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Tina swims 4 miles upstream at 1 mph |
2007-03-31 |
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Michael pose la question :
If Tina swims 4 miles upstream at 1 mph and back downstream to the same point to the same point at 4 mph, what is her average speed?
Penny Nom lui répond. |
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A beam on a lighthouse |
2007-03-28 |
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Lisa pose la question :
A beam on a lighthouse 2000 metres away from the nearest point P on a straight shoreline revolves at the rate of 10 pi radians per minute. How fast is the beam of the light moving along the shoreline when it is 500 metres from P?
Stephen La Rocque lui répond. |
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The velocity of an aircraft |
2007-03-22 |
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William pose la question :
Hello,
I don't understand how to work this problem. Thanks in advance for your help!
A jet moving at 500.0 km/h due east moves into a region where the wind is blowing at 120.0 km/h in a direction 30.0 degrees north of east. What is the new velocity and direction of the aircraft relative to the ground?
Penny Nom lui répond. |
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How long does she have to get out of the way? |
2007-02-23 |
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Sharon pose la question :
How do I solve this? The height h (in feet) of an object that is dropped from the height of s feet is given by the formula h = s - 16t^2 , where t is the time the object has been falling. A 6 foot tall woman on a sidewalk looks directly overhead and sees a window washer drop a bottle from the 6 story. How long does she have to get out of the way? Round to the nearest tenth. (A story is 12 feet.)
Penny Nom lui répond. |
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Acceleration |
2007-02-20 |
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thomas pose la question :
Don't know if this service still exists. ACCELERATION CALCULATION initial vel 0km/hr final vel 24km/hr time 3s
Stephen La Rocque lui répond. |
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Increasing speed and decreasing time |
2007-02-18 |
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Nigel pose la question :
I am completely lost...can you help with this: The time, t, to travel a distance, d, at a constant speed, v, can be obtained from the formula: d = vt. If the speed is increased by x, find an expression to represent the decrease in time to travel the same distance.
Stephen La Rocque lui répond. |
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A person jumps from the roof of a house |
2007-02-13 |
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Jessie pose la question :
A person jumps from the roof of a house 3.9m high. When he strikes the ground below, he bends his knees so that the torso decelerates over an approximate distance of 0.70m. If the mass of his torso (excluding legs) is 42kg, find a) his velocity just before his feet strike the ground , and b) the average force exerted on his torso by his legs during deceleration.
Please provide calculations and answers for comparison.
Stephen La Rocque lui répond. |
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Romeo is throwing pebbles |
2007-02-08 |
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Jessie pose la question :
Romeo is chucking pebbles gently up to Juliet's window, and he wants the pebbles to hit the window with only a horizontal component of velocity. He is standing at the edge of a rose garden 4.5m below her window and 5.0m from the base of the wall. How fast are the pebbles going when they hit her window?
Stephen La Rocque lui répond. |
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Driving on a banked roadway |
2007-02-05 |
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William pose la question :
A race track is shaped like an inverted cone. Race cars drive around this track in a horizontal path. If a drivers speed is 34 m/s, at what distance from the tip of the cone should he drive his car if there is no friction?
THANKS IN ADVANCE FOR ANY ASSISTANCE YOU CAN PROVIDE!
Sincerely,
William Bush
Stephen La Rocque lui répond. |
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A boat travels 60 miles downstream in the same time it takes to go 36 miles upstream |
2007-01-27 |
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Liz pose la question :
A boat travels 60 miles downstream in the same time it takes to go 36 miles upstream. The speed of the boat in still water is 15 mi/h greater than the speed of the current. Find the speed of the current.
Stephen La Rocque lui répond. |
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Freefalling objects |
2007-01-25 |
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Patricia pose la question :
How long will it take a stone dropped from atop a 1000-meter tall building to reach the ground?
Stephen La Rocque lui répond. |
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At what speeds were they travelling? |
2007-01-16 |
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Maria pose la question :
Kim and Julie are joining Nicole at her parents cottage for the weekend. The cottage is 150km away from their neighbourhood. Kim can leave directly after school but Julie will be leaving after band practice, an hour and a quarter later. Kim took her time and drove slowly, averaging 20km/h slower than Julie. They both arrived at the same time.
At what speeds were they travelling?
Stephen La Rocque lui répond. |
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Throwing a stone downwards |
2007-01-12 |
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Momo pose la question :
a stone is thrown vertically downward with an initial speed of 14m/s from a height of 65 m above the ground. A) how far does the stone travel in the first 2.0 s? B) what is the stone velocity just before it hits the ground?
Stephen La Rocque lui répond. |
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Find the distance function s(t) given the acceleration function a(t) |
2006-11-16 |
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David pose la question :
Find the distance function s(t) of the acceleration function: a(t)= sin(0.1t)/ cos^3(0.1t)
Penny Nom lui répond. |
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Pulleys and belts |
2006-10-31 |
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Lynn pose la question :
A belt has a linear speed of 32 mph. It is spinning three pulleys.
Pulley A has diameter 14 in. radius = 7 inches
Pulley B has diameter 26 in. radius = 13 inches
Pulley C has radius 3 ft. radius = 36 inches Angular speed in Radians per min for
I got
Pulley A= .08 rads/min Pulley B= .04 rads/min Pulley C=.01 rads/min How many cm would pulley C travel in 14 seconds?
Penny Nom lui répond. |
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Angular speed |
2006-10-04 |
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Jack pose la question :
A horse on a merry-go-round is 7m from the center and travels at a speed of 10km/h. What is its angular speed?
Stephen La Rocque lui répond. |
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The velocity of a pendulum, part II |
2006-09-07 |
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Erin pose la question :
We saw the question in your database about the velocity of a pendulum swinging.....It is the same exact question....but there is another question......it says....
"estimate the instantaneous rate of change of d with respect to t when t = 1.5. At this time, is the pendulum moving toward or away from the wall? Explain."
Harley Weston lui répond. |
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A point on a bicycle rim |
2006-08-01 |
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Sonu pose la question :
Find the speed in m/s of a point on a bicycle rim of diameter 88cm making 200 revolutions per minute.
Penny Nom lui répond. |
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Flying with and against the wind |
2006-07-06 |
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Tim pose la question :
When a plane flies with the wind, it travels 800 miles in 4 hours. Against the wind it takes 5 hours to cover the same distance. Find the rate of the plane in still air and the rate of the wind.
Stephen La Rocque lui répond. |
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Angular velocity |
2006-03-28 |
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Ben pose la question :
How do you (a) express angular speed in terms of linear speed and (b) express linear speed in terms of angular speed?
Stephen La Rocque lui répond. |
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Orbital velocity |
2006-02-15 |
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Lizzie pose la question :
Assume the world is a spherical planet with a diameter of 1600 KM. with a uniform density or 5200 KM.
It the moon is in a circular orbit of 630 KM. above the surface of the world,what is it's orbital velocity in metres per second?Round to the nearest WHOLE number.
Stephen La Rocque lui répond. |
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Find the ground speed and the planes true heading. |
2006-02-05 |
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Jimmie pose la question :
An aircraft going from city A to city B on a bearing of S69E (degrees) is traveling at a speed of 430 mph. The wind is blowing out of the north to south at a speed of 25 mph. Find the ground speed and the planes true heading.
Penny Nom lui répond. |
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What initial velocity is required to double the maximum height |
2006-01-14 |
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A photographer pose la question :
A body is thrown into the air with an initial velocity V ft./sec. What initial velocity is required to double the maximum height previously obtained?
Penny Nom lui répond. |
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Velocity and acceleration |
2005-10-27 |
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Candace pose la question :
When taking the integral of the position function, you get the velocity function, and the same for velocity to acceleration. So when you do each of these, you get a function. But when you integrate on a graph, you get an area under a curve. The area is un units squared- where do the units go when you make it an equation? How can a function be an area?
Harley Weston lui répond. |
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Speed on a bicycle |
2005-07-27 |
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Deborah pose la question :
We are trying to figure out how many miles per hour we rode in a bike race. If the distance was l5 miles and the time it took was was 55 minutes, what is the speed?
Penny Nom lui répond. |
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An aircraft is flying directly from airport A to airport B |
2004-10-22 |
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A student pose la question :
In this question, i is a unit vector due east and j is a unit vector due north. An aircraft is flying directly from airport A to airport B, which is 2000 km from A. The velocity in still air of the aircraft is (150i+50j)km/h and the ground speed is (200i-30j)km/h. Calculate
(i) the time of flight, to the nearest min
(ii) the direction of the wind.
Penny Nom lui répond. |
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Cycling in the wind |
2004-10-11 |
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A student pose la question :
A cyclist is travelling in the direction of 12i+5j at a speed of 39 km/h where i is a unit vector due east and j is a unit vector due north. The wind appears to the cyclist to be blowing with a velocity of (-4i+j) km/h. Find, correct to 1 d.p
(a) the true speed of the wind and
(b) the bearing from which the wind is blowing
Penny Nom lui répond. |
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Angular speed |
2004-02-01 |
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Rachel pose la question :
A 4 inch pulley on a motor makes 1500 revolutions/minute. It is connected to an 8 inch saw blade.
a. Find the angular speed of the pulley in radians/minute
b. Find the angular speed of the saw in radians/ minute
Harley Weston lui répond. |
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The London marathon |
2004-01-27 |
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Nina pose la question :
After a years training, Minnie Midriffe increased her average speed in the london marathon by 25%. By what percentage did her time decrease?o
Penny Nom lui répond. |
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What is the speed of the automobile? |
2004-01-20 |
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Rita pose la question :
An automobile travels toward Nashville from Cookeville. It takes 33 minutes to travel from Cookeville to Manchester, which is a 36 mile distance. If the driver continues at this pace, what is the speed of the automobile?
Penny Nom lui répond. |
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A rock on a string |
2003-10-26 |
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A student pose la question :
a rock on a 4' string is rotated at 80 rpm. what is the linear speed in feet per second? in miles per hour?
Penny Nom lui répond. |
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A boat travels 12 km upstream... |
2003-09-03 |
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Sohaib pose la question :
A boat travels 12 km upstream and back in 1 hour 45 minutes. If the speed of the current is 3km/hr throughout, find the speed of the boat in still water, giving your answerÝcorrect to 3 decimal places.
Penny Nom lui répond. |
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A helicopter rises vertically |
2003-09-02 |
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Kate pose la question :
A helicopter rises vertically and t seconds after leaving hte ground its velocity is given in feet per second by v(t) = 8t + 40 / (t+2)2 How far above the ground will the helicopter be after 3 seconds?
Penny Nom lui répond. |
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A radio controled car |
2003-06-08 |
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Robert pose la question :
I have a radio controled car (scale size 1/43). This car can travel 490 ft. per minute. I would like to know how fast that is at that scale size in miles per hour (and Kilometers per hour)?
Penny Nom lui répond. |
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Two rate problems |
2002-09-30 |
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Rebecca pose la question :
- There are two small holes in the bottom of a tub filled with water. If opened, one hole will empty the tub in three hours; the other will empty it in six hours. If both holes are opened at the same time, how long will it take to empty the tub?
- An airplane flies 400 miles per hour in calm air. It can cover 900 miles flying with the wind in the same time that it can cover 700 miles against the wind. What is the speed of the wind?
Penny Nom lui répond. |
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A good rule of thumb when driving |
2002-06-13 |
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Lisa pose la question :
A good rule of thumb when driving is that you should be about one car length away from the car in front of you for every 10 miles per hour that you are travelling. Suppose you follow this rule perfectly (so you are exactly the correct distance away). You are waiting at a stop light with your front bumper just touching the car in front of you. The light turns green and the car in front accelerates at a constant rate "r". Calculate how you should accelerate in order to follow the rule.
Penny Nom lui répond. |
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Flying with the wind |
2002-05-19 |
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SaraJean pose la question :
It takes 6 hours for a plane to travel 720 km with a tail wind and 8 hours to make the return trip with a head wind. Find the air speed of the plane and the speed of the wind current.
Penny Nom lui répond. |
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A test drive |
2002-04-23 |
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Jennie pose la question :
At 9 A.M. a test car driving at a constant speed passes a marker 50 miles from it's starting point. At noon the car is about 130 miles from the marker. If the test drive ends at 1:30 P.M., how far will the car be from its starting point?
Penny Nom lui répond. |
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How far does the fly fly? |
2001-08-07 |
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Harold pose la question :
6 MPH 4 MPH
Rachel ---------------------- Eli
10 Miles apart
The fly is on Rachels handlebars. The fly is scared so it flys back and forth at 20 MP H. How far has the fly flown when Rachel and Eli meet? f
Penny Nom lui répond. |
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A jogger |
2001-03-12 |
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Bill pose la question :
At time t=0 a jogger is running at a velocity of 300 meters per minute. The jogger is slowing down with a negative acceleration that is directly propotional to time t. This brings the jogger to a stop in 10 minutes. a) write an expression for the velocity of the jogger at time t. b) what is the total distance traveled by the jogger in that 10-minute interval.
Harley Weston lui répond. |
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Cincinnati to Winston-Salem |
2001-01-23 |
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Belinda pose la question :
Joan Bedney travels from Cincinnati to Winston-Salem at an average rate of 40 miles per hour and returns at an average rate of 60 miles per hour. What is her average speed for the trip?
Leeanne Boehm and Claude Tardif lui répond. |
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Lobbing a tennis ball |
2000-10-31 |
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Alex pose la question :
If a tennis ball is lobbed into the air with an initial upward velocity of 12 meters per second, its velocity and height will be functions of time in flight described by the following rules: V=12-9.8T and H=1+12T-4.9T 2 Find the maximum height of the tennis ball and the time it takes to reach that height.
Penny Nom lui répond. |
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Gravity |
2000-09-06 |
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Robert Broomfield pose la question :
If they dropped a 1lb object from 40,000 feet in the air, at what speed would it it the ground?
Harley Weston lui répond. |
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Velocity of a pendulum |
2000-08-28 |
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Mekca pose la question :
A pendulum hangs from the ceiling. as the pendulum swings, its distance,d cm, form one wall of the room depends on the number of seconds,t, since it was set in motion. assume that the equation for d as a function of t is: d=80+30cos3.14/3t, t>0. estimate the instantaneous rate of change of d at t=5 by finding the average rates for t=5 to 5.1, t=5 to 5.01, and t=5 to 5.001.
Harley Weston lui répond. |
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PreCalculus |
2000-08-09 |
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Angela pose la question :
Use absolute values to define the interval or pair of intervals on the real line.
<--|--- |--- ]--- |--- |--- |--- [---| ---|-->
18 19 20 21 22 23 24 25 26
A car is moving at the rate of 50 miles per hour, and the diameter of its wheels is 2.5 feet.
a) Find the number of revolutions per minute that the wheels are rotating.
b) Find the angular speed of the wheels in radians per minute.
Harley Weston lui répond. |
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The speed of light |
2000-06-19 |
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Benny Lau pose la question :
I have a personal questions. In physics,if a person is running on a train, his relative speed on the ground will be the addition of the speed of train and the person. If u have a train inside another train and inside another train, so on...... can u reach the speed of light? It would need a very long distance. But if we make all the train travel in circles. Then we don't need that much distance. So can we achieve the speed of Light?
Robert Coleman and Harley Weston lui répond. |
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Angular velocity |
2000-05-24 |
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Ashley Milliman pose la question :
The crankshaft of a particular automobile engine has an angular velocity of 1,500 rpm at 30 mph. The crankshaft pulley has a diameter of 10 cm, and it's attached to an air conditioner compressor pulley with a 7 cm diameter and an alternator pulley with a 5 cm diamter At what angular velocities do the compressor and alternator turn? .
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Harley Weston lui répond. |
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Running Through a Train Tunnel |
2000-04-01 |
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Eugene Chan pose la question :
A man is running through a train tunnel. When he is 2/3 of the way through, he hears a train that is approaching the tunnel from behind him at a speed of 60 mph. Whether he runs ahead or back, he will reach an end of the tunnel at the same time the train reaches that end. At what rate, in miles per hour, is he running? (Assume he runs at a constant rate.) I think the answer (12 mph) is wrong. Also, I believe it should read 1/3 of the way through, but don't know how to prove it. Could you come up with some way to prove it, please? I would really appreciate it.
Penny Nom lui répond. |
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Word problems |
2000-03-31 |
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Amy pose la question :
Question: - a north bound train left at noon. four hours later a south bound train left the same station. at 5 o'clook they were 160 miles apart. what was the rate of both if the north bound train was going 20 miles faster than the other one.
- clark's final exam was given 5 times the weight of the weight of a weekly test. the avgerage of 15 weekly test was 91. the overall weighted average was 85. what did he make on the final.
Penny Nom lui répond. |
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Travelling from A to B |
2000-03-20 |
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Matt pose la question :
A car is traveling from point A to point B. Point A and point B are 30 miles apart. A car travels 30 miles an hour from point A to point B and then goes back to point A. How fast does the car have to go back to average 60 miles an hour?
Claude Tardif lui répond. |
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