The kinetic energy of a body is doubled when its
- A. mass is halved
- B. speed is doubled
- C. speed is increased by a factor of the square root of two
- D. mass is doubled and speed halved
Explanation
Kinetic energy is half m v squared, so it scales with the square of the speed. Multiplying the speed by root 2 multiplies the energy by 2, whereas doubling the speed multiplies the energy by 4. The last option leaves energy at half its original value, since doubling m and quartering v squared gives a net factor of one half.
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