Answer: Total mechanical energy is constant.
- A Kinetic energy alone stays constant throughout the motion
- B Potential energy alone stays constant throughout the motion
- C Total mechanical energy is constant
- D The work done by the force is always at its maximum possible value
Correct answer: C. Total mechanical energy is constant
Explanation: For conservative forces (gravity, spring), mechanical energy (KE + PE) is conserved.
As a pendulum swings, total mechanical energy (KE+PE) stays constant: at the highest points A and C, all energy is potential (zero speed); at the lowest point B, all of that energy has converted into kinetic energy (maximum speed).
Concept context
Work-energy theorem, potential energy, conservation of energy, collisions.