Question

A 4-kg object falls vertically a distance of 5 m. its potential energy has changed by approximately how much?

Answer 1

Given:
m = 4 kg, the mass of the object
h = 5 m, distance fallen

Neglect air resistance.

The PE (potential energy) is 
PE = mgh = (4 kg)*(9.8 m/s²)*(5 m) = 196 J

The PE is converted into KE (kinetic energy) after the fall. 
Therefore the PE decreased by 196 J ≈ 200 J

Answer: d. It has decreased by 200 J