If the speed of a car is doubled, its kinetic energy becomes
- A. double
- B. four times
- C. half
- D. unchanged
Explanation
Kinetic energy depends on the square of the speed, so a factor of two in speed gives a factor of four in energy, and the braking distance rises in the same proportion since the brakes must dissipate all of it. This is the physics behind speed limits. The momentum, meanwhile, only doubles.
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