Not moving ==> zero kinetic energy Highest altitude ==> maximum potential energy ------------------------------------ Total energy ==> all potential
Halfway up, halfway down ( B ) ...
Half-altitude ==> half of total energy is potential Moving ==> some kinetic energy; must be half of total ----------------------------------------- Total energy ==> same total; half potential, half kinetic
Lowest point ( C ) ...
Minimum altitude ==> zero potential energy Fastest speed ==> maximum kinetic energy ----------------------------------------- Total energy ==> same total; no potential, all kinetic
The total energy at A, B and C is constant and does not change.
At A, all the energy is potential energy. It gets converted partially to kinetic energy at B and is completely converted to kinetic energy at C. At C, all the energy is kinetic energy.