Question

Students drop a 2 kg object from rest out a window that has a

height of 10 m during a lab experiment. The students time the

object to hit the ground and measure 1.2 s. Calculate the

difference between the PE at the top and the KE at the bottom.

a. greater than 75 J

b. less than 25 J

c. between 25 J & 50 J

d. between 50 J & 75 J

Answer 1

a. greater than 75 J

Explanation:

Potential Energy at the top = mgh

Mass m = 2kg

g = 9.8m/s^2

height h = 10m

Potential Energy at the top = 2 * 10 * 9.8

Potential Energy at the top = 196Joules

The object is not moving at the bottom, hence the KE of the body at the bottom is 0Joules

difference between the PE at the top and the KE at the bottom = 196 - 0 = 196Joules

Hence the difference between the PE at the top and the KE at the bottom is greater than 75Joules