Single correct option
A satellite moves in a circular orbit around the Earth at constant speed. The work done by the centripetal force on it in one complete revolution is
- A. positive and equal to its kinetic energy
- B. zero
- C. negative and equal to its potential energy
- D. equal to mv²
Show answer and solution
Answer: (B) zero
The centripetal force always acts towards the centre, at 90° to the velocity, so W = F·d·cos 90° = 0 for every small displacement. The speed and kinetic energy therefore stay constant. The force is large but does no work, which is the trap.
Saved on this device. Sign in or create a free account to keep it on every device.