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A disc of mass m and radius r is gently placed on another disc of mass 2m and radius r. The disc of mass 2m is rotating with angular velocity `omega_(0)` initially. The disc is placed such that axis of both are concident. The coefficient of friction is `mu` for surfaces of contact Assume that pressure on disc is uniformely distributed. Time elapsed in this processA. `(omega_(0)R)/(mug)`B. `(2omega_(0)R)/(mug)`C. `(omega_(0)R)/(2mug)`D. `(omega_(0)R)/(4mug)` |
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Answer» Correct Answer - B `sigma=(-((Deltar)/(r)))/(((Deltal)/(l)))` `(DeltaA)/(A)=(2Deltar)/(r)=-2%implies ((Deltar)/(r))~=-1%` `sigma=-(((Deltar)/(r)))/(((Deltal)/(l)))` `(0.4) =-((-1%))/(((Deltal)/(l)))implies ((Deltal)/(l))=(10)/(4)% " "(Deltal)/(l)=2.5%` |
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