A 0.5 kg ball moving at 6 m/s has kinetic energy
- A. 9 J
- B. 18 J
- C. 6 J
- D. 3 J
Explanation
Kinetic energy is half mv squared, so half multiplied by 0.5 multiplied by 36 gives 9 J. Forgetting the factor of one half gives 18 J, which is the commonest slip. Note that the momentum of the same ball would be 3 kg m per second, which is why 3 also appears as a distractor.