Question

 

A) If you are sitting at your desk how fast do you need to throw an eraser so that it hits the ceiling?

B) Calculate how high you could throw a ball.

C) If you dropped a coin from our classroom window, how long would it take to hit the ground?

D) Make up your own question. Find the details of an object moving horizontally and use those numbers to calculate the acceleration of that object.

Answer 1

Suppose that you are throwing eraser as such speed and angle such that we can say that the path of the eraser is approximately a straight line.

Suppose that your firing angle of the eraser is at theta angle from the horizon.

Using Newton's laws of motion we can say that

as g is acting in negative direction. Here we have assumed that eraser just touches the roof so v_y=0.

.

b)

For maximum height we will throw the ball in perfectly perpendicular direction to the horizon. So .

    Maximum height depends upon the initial velocity,

c) Using Newton's laws of motion,

Here we are dropping the ball so v_0 = 0. So time required to hit the ground if distance between ground and window is h.

d) Suppose a car is moving at a constant acceleration on the straight frictionless road.

If we measure the speed v_1 of the car at time t_1 and car travels further for some time and now we measure the velocity v_2 at time t_2. We can measure the distance travelled by the car in this time interval(say s).

Acceleration a of the car is .