Gravitational potential energy (Ep = m g h)

How gravitational potential energy builds and releases

Follow one object through the process — from being lifted to falling.

1. 1Object is lifted upwardA force acts on the object over a vertical distance. Work is done against gravity, so energy is transferred from whatever is doing the lifting into the object's gravitational potential store.+
2. 2Object sits at height hThe object now has gravitational potential energy equal to Ep = m g h. This energy is stored — not released yet. It depends on mass, gravitational field strength, and the vertical height above the reference point.+
3. 3Object begins to fallAs the object descends, height h decreases. The gravitational potential energy store empties — energy is transferred into the kinetic energy store. The object speeds up.+
4. 4Object reaches the groundAt the original reference height, h = 0, so Ep = 0. All the original gravitational potential energy has been transferred — into kinetic energy (and some thermal energy if friction acted). The energy stores have changed but the total energy is conserved.

Stop and predict

Commit to an answer before you reveal — this is where the learning happens.

A 2 kg book is placed on a shelf 1 m high. A 4 kg book is placed on a shelf 0.5 m high. Using g = 9.8 N/kg — which book has MORE gravitational potential energy stored?

Tap any cell to reveal it. Tap a column header to read one property down every item.

Taken directly from the exam-board specification.