A 4-kg object falls vertically a distance of 5 m. Its potential energy has changed by approximately how much?
A) It has increased by 20 J.
B) It has decreased by 200 J.
C) It has decreased by 20 J.
D) It has increased by 200 J.

Question

Quizplus · Accepted Answer

The potential energy (PE) changes by $PE = mgh$, where $m = 4 \, \text{kg}$, $g = 9.8 \, \text{m/s}^2$, and $h = 5 \, \text{m}$. Thus, $PE = 4 \times 9.8 \times 5 = 196 \, \text{J}$. Since the object falls, its potential energy decreases, so the closest answer is a decrease by 200 J.

A 4-Kg Object Falls Vertically a Distance of 5 M