Question

Determine how potential and kinetic energy changes at each position of the pendulum as the ball swings from A to E.

Position A:

Position B:

Position C:

Position D:

Position E:

Answer 1

I’ll assume the pendulum swings from a highest point at A, through intermediate B, the lowest point C, then through D to the opposite highest point E. Ignoring friction/air resistance (mechanical energy conserved):

- Position A: Potential energy (PE) maximum, kinetic energy (KE) zero (momentarily at rest).
- Position B: PE has decreased from A, KE has increased (some PE converted into KE).
- Position C: PE minimum, KE maximum (fastest speed; most energy in kinetic form).
- Position D: PE increasing, KE decreasing (kinetic energy converting back into potential).
- Position E: PE maximum (same as A if no losses), KE zero (momentarily at rest).

Total mechanical energy remains constant; speed increases toward C and decreases away from C.