Question

A 15kg object strikes the ground with 2000J of kinetic energy after freely falling from rest. How far above the ground was the object when it was released?

Answer 1

Answer:

Explanation:

Find the final velocity at which it struck the ground by using the kinetic energy formula.

$KE=\frac{1}{2} mv^2$

$2000=\frac{1}{2} (15)v^2\\v=16.33$

Now use kinematics to solve for the vertical displacement. We were given the initial velocity and acceleration can be assumed to be 9.8

$V^2=V^2_i+2a(y_f-y_i)\\16.33^2=0^2+2(9.8)(y_f-y_i)$

Δy = 13.6 meters