4.5.2—Gravitational potential energy

Near Earth’s surface, gravitational potential energy change is ΔE=mgh relative to a chosen reference level. Only differences matter, so the zero level can be selected for convenience.

Use energy conservation when no non-conservative work acts, and include kinetic and elastic terms as needed. Far from Earth, the uniform-field approximation may fail.

Raising 2 kg by 3 m where g=9.8 gives an increase of 58.8 J.

Potential energy itself is reference-dependent; a negative value is not automatically an error.