MCQ practice · SSC Physics Board questions · Chapter 4: Work, Power and Energy
If the mass of a body is halved and its velocity is made four times, the kinetic energy becomes how many times the previous value?
Think it through first, then pick an option.
- a double
- b four times
- c eight times
- d sixteen times
Answer and explanation
Correct answer: c eight times
T = ½mv². Halving the mass gives ×1/2 and four times the velocity gives ×16 (v is squared), so the energy becomes 1/2 × 16 = 8 times.
Why the other options are wrong
- a double: This is not the answer: T = ½mv². Halving the mass gives ×1/2 and four times the velocity gives ×16 (v is squared), so the energy becomes 1/2 × 16 = 8 times.
- b four times: This is not the answer: T = ½mv². Halving the mass gives ×1/2 and four times the velocity gives ×16 (v is squared), so the energy becomes 1/2 × 16 = 8 times.
- d sixteen times: This is not the answer: T = ½mv². Halving the mass gives ×1/2 and four times the velocity gives ×16 (v is squared), so the energy becomes 1/2 × 16 = 8 times.
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