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A particle begins SHM from the mean position (origin) with a time period of 2 s. After how much time will its kinetic energy become 75% of the total mechanical energy?
- 1/6 s
- 1/4 s
- 1/3 s
- 1/2 s
Correct answer: 1/6 s
Solution
From mean position x = A sin(wt). KE = 0.75 E means PE = 0.25 E -> x = A/2 -> sin(wt)=1/2 -> wt = pi/6. With T = 2 s (w = pi), t = (pi/6)/pi = 1/6 s.
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