When the speed of your car is halved, by what factor does its kinetic energy decreases?
Correct answer: B. ¼
- A. ½
- B. ¼
- C. ⅛
- D. ⅙
Explanation
KE=½ mv2KE= ½ m(½v)2KE=⅛ mv2As it can be seen, the fraction reduces from 1/2 to 1/8 which means the Kinetic Energy decreased by 4 times or 1/4.
This question appeared on the PMC National MDCAT 2020 paper, which you can sit online with every answer explained.
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About Kinetic Energy
Kinetic energy is the energy of motion, given for a nonrelativistic object by K = ½mv², so it depends on mass and the square of speed. Questions connect kinetic energy with work through the work energy theorem, calculate changes in kinetic energy, and distinguish it from momentum and potential energy.
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