Question

How high must a body be lifted to gain an amount of potential energy equal to the kinetic energy it has. When moving at sped 20ms^-1. The value of acceleration due to gravity at that place is g = 9.8 ms^-2.

Answer 1

mgh = \(\frac{1}{2}\)mv²

i.e. 9.8 h = \(\frac{1}{2}\) × 20 × 20

h = \(\frac{200}{9.8}\)= 20.4 m.