If the momentum of a body decreases by 20% the percentage decrease in K.E will be:
Correct answer: B. 36%
- A. 44%
- B. 36%
- C. 28%
- D. 20%
Explanation
Momentum p = mvIf momentum is decreased by 20%, the resulting new value is 80% of the original p-p'P - 0.2p = mv - m0.2vP - 0.2p = (m) (v) (0.8)K.E = ½ mv²= ½ m (0.64v²)K.E = 36%
This question appeared on the ETEA MDCAT 2013 paper, which you can sit online with every answer explained.
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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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