A 0.5 kg ball is dropped from a height of 4 meters above the ground. Assuming no air resistance, calculate the gravitational potential energy at the top and the kinetic energy just before it hits the ground.

Step-by-step solution

1. Use the formula for potential energy $PE=mgh$ with $m=0.5\mathrm{kg}$, $h=4\mathrm{m}$, $g=9.8m/{\mathrm{s}}^2$. Compute $PE=0.5\times 9.8\times 4=19.6\mathrm{J}$.
2. Since there is no friction, all the potential energy converts to kinetic energy. Thus $KE=19.6\mathrm{J}$ just before impact.

Concept tested: Potential and Kinetic Energy

Published 1 October 2026 · How this solution was prepared and checked