5.2.2—The formula ∆EP = mg∆h for gravitational potential energy changes in a

In a uniform field, the change in gravitational potential energy is ∆E_P=mg∆h, with g treated as constant over the height interval.

Define the reference level and keep the sign of ∆h consistent. Only differences in potential energy affect energy conservation calculations.

A 0.50 kg mass lowered 4.0 m has ∆E_P=−19.6 J relative to its starting level; that energy can become kinetic or thermal.

Zero potential at the floor is a choice, not a physical claim that the object has no energy anywhere else.