Energy in a pendulum sim
Pulled aside, the bob is higher than at the bottom, so it has energy in its gravitational potential store: m g h.
Energy in a pendulum · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Pulled aside, the bob is higher than at the bottom, so it has energy in its gravitational potential store: m g h. Let go, it falls and speeds up; the energy goes into its kinetic store, ½ m v². At the bottom h = 0 and all of it is kinetic; then it climbs and the kinetic store empties back into the gravitational one. From 30°: h = 6.7 cm, so m g h = 67.0 mJ, and at the bottom v = 1.16 m/s. With no air resistance the total stays the same, so the bob always comes back to the same height. With air resistance some energy goes into the thermal store of the bob and the air on every swing; the swings die away, but the total of all the stores never changes: energy is conserved. Taking g = 10 N/kg.
- The bob's height above its lowest point
- Right: the energy stores
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