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A hollow spere of mass M and radius R is rotating with angular frequency `omega` it suddenly stops rotating and 75% of kinetic energy is converted to heat if s is the speicific heat of the material in j / kg k then rise in temperature of the spere is (MI of hollow sphere `=2/3MR^(2)`A. `(R omega)/(4s)`B. `(R^(2)omega^(2))/(4s)`C. `(R omega)/(2s)`D. `(R^(2)omega^(2))/(2s)` |
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Answer» Correct Answer - b Intial rotational kinetic energy of the hollow sphere `k_(i)=1/2xxIomega^(2)=1/2 xx2/3mr^(2)xx(v^(2))/(r^(2))` `=1/3 mv^(2)=1/3m xx omega^(2)R^(2)` according to the question `rarr 3/4xx1/3 omega^(2)R^(2)=S Delta theta` `therefore` Rise in temperature of the sphere `Delta theat =1/4 (omega^(2)R^(2))/(S)` |
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