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A pendulum bob has a speed of `3ms^(-1)` at its lowest position. The pendulum is `0.5` m long. The speed of the bob, when string makes an angle of `60^(@)` to the vertical is `("take, g"=10ms^(-1))`A. `(3)/(2)m//s`B. 2m/sC. `(1)/(2)m//s`D. 3m/s |
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Answer» Correct Answer - B According to the law of conservation of energy `TE_(at""L) = TE_(at""h)` `(1)/(2)mv^(2) = (1)/(2)"mu"^(2) + mgh` `v^(2) = u^(2) + 2gh or u^(2) = v^(2) - 2gh` ` u^(2) = 9 - 2 xx 10 xx (1)/(2)(1-(1)/(2))` `u^(2) = 9 - 5 = 4` ` u=2 ms^(-1)` |
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