Answer: Joule.
- A Watt
- B Newton
- C Joule
- D Pascal
Correct answer: C. Joule
Explanation: The SI unit of work is the Joule (J) = Newton x metre = kg m<sup>2</sup>/s<sup>2.</sup>
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.