







A penny is thrown from the top of a building 
20180316 

Zoraida pose la question : A penny is thrown from the top of a 26.7meter 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. 





Distance as a function of acceleration 
20130710 

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. 





Uniform acceleration 
20111206 

Android pose la question : At a certain instant, two cars A and B are 2000 ft apart. At this instant, car A is traveling at 15 miles/hr. and accelerating at 3 ft/s^2 while B is moving towards A at 30 miles/hr. and an acceleration of 2 ft/s^2.
Find the ff:
a.) The possible time of their collusion in minutes.
b.) The distance in ft. each has traveled before collusion. Penny Nom lui répond. 





A falling object 
20090201 

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. 





What will be its speed after 10s? 
20090201 

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. 





Time with NonUniform Motion 
20080721 

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. 





Throwing a ball on the moon 
20080521 

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. 





At what value of t is the maximum acceleration? 
20080425 

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)=x5 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. 





Two points moving on a straight line 
20080306 

laura pose la question : Particle A travels at constant speed of 1.0ms1 in straight line, passing particle B, at which time particle B beings traveling with constant acceleration of 0.2ms2 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. 





How far from the corner will the police catch the car? 
20080127 

Joel pose la question : A car is going down the road at a speed of 90km/h in a 50km/h zone.
As the car passes a corner, a police cruiser sitting there notices it. Five
seconds later the cruiser begins accelerating at 5.0m/s squared.
Assuming that he is able to maintain this acceleration, how far from the
corner will the police catch the car? How fast will the cruiser be going? Stephen La Rocque lui répond. 





Constantly accelerated motion 
20071029 

Priyanka pose la question : A, B and C are three points lying in that order on a straight line. A body is
projected from B towards A with speed 3 m/s. The body experiences an
acceleration of 1 m/s^2 towards C. If BC =20 m, find the time taken to reach C and
the distance travelled by the body from the moment of projection until it reaches C. Stephen La Rocque lui répond. 





The second derivative 
20070414 

Gerry pose la question : In mathematical context,what do you understand by the term "Second Derivative" Penny Nom lui répond. 





How long does she have to get out of the way? 
20070223 

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. 





Acceleration 
20070220 

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. 





A person jumps from the roof of a house 
20070213 

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. 





Freefalling objects 
20070125 

Patricia pose la question : How long will it take a stone dropped from atop a 1000meter tall building to reach the ground? Stephen La Rocque lui répond. 





Throwing a stone downwards 
20070112 

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. 





Find the distance function s(t) given the acceleration function a(t) 
20061116 

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. 





Velocity and acceleration 
20051027 

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. 





Accelerating to the speed of light 
20040930 

Lars pose la question : How long time would it take to accelerate up to the speed of light with an acceleration speed similar to 0100 seconds in 5 seconds? Penny Nom lui répond. 





g on Mars 
20040122 

RC pose la question : To measure the acceleration on Mars an object is dropped from a height of 160m. It takes 10s for this object to hit the ground. What is the value for g on Mars?g Penny Nom lui répond. 





A helicopter rises vertically 
20030902 

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. 





A good rule of thumb when driving 
20020613 

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. 





A jogger 
20010312 

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 10minute interval. Harley Weston lui répond. 





Gravity 
20000906 

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. 

