InterviewSolution
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InterviewSolution
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A circular disc `X` of radius `R` is made from an iron of thickness `t`, and another disc `Y` of radius `4R` is made from an iron plate of thickness `t//4`. Then the relation between the moment of mertia `I_(x)` and `I_(Y)` is :A. `I_(Y) = 32 I_(x)`B. `I_(Y) = 16 I_(x)`C. `I_(Y) = I_(x)`D. `I_(Y) = 64 I_(x)`. |
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Answer» Correct Answer - D Mass of disc `(X), mx = pi R^(2) t rho` where `rho` = density of material of disc :. `1_(X) = (1)/(2) m_(X) R^(2) = (1)/(2) R^(2) t rho R^(2)` `1_(X) = (1)/(2) pi rho R^(4)` Again mass of disc `(Y)` `m_(y) = pi = (4 R)^(2) (t)/(4) rho = 4 pi R^(2) t rho` and `I_(Y) = (1)/(2) m_(Y) (4R^(2)) = (1)/(2) 4 pi R^(2) t rho. 16 R^(2)` `rArr I_(Y) = 32 pi t rho R^(4)`...(ii) :. `(l_(y))/(l_(x)) = (32 pi t rho R^(4))/((1)/(2) pi rho t R^(4))` `rArr = 64` :. `1_(Y) = 64 1_(X)`. |
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