Rotational Motion

JEE Main level, numerical answer, medium

247 of 280

Question 247 of 280

A solid sphere and a hollow cylinder roll up without slipping on same inclined plane with same initial speed vv. The sphere and the cylinder reaches upto maximum heights h1h_1 and h2h_2, respectively, above the initial level. The ratio h1:h2h_1: h_2 is n10\frac{n}{10}. The value of nn is______.

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Answer: 7

Gain in P.E. = Loss in K.E.
mgh=12mv2(1+K2R2)\mathrm{mgh}=\frac{1}{2} \mathrm{mv}^2\left(1+\frac{\mathrm{K}^2}{\mathrm{R}^2}\right)
h∝1+K2R2\mathrm{h} \propto 1+\frac{\mathrm{K}^2}{\mathrm{R}^2}
h1 h2=1+251+1=75×2=710\frac{\mathrm{h}_1}{\mathrm{~h}_2}=\frac{1+\frac{2}{5}}{1+1}=\frac{7}{5 \times 2}=\frac{7}{10}
n=7\mathrm{n}=7

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