InterviewSolution
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InterviewSolution
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A ball of radius r and density r falls freely under gravity through a distance h before entering water. Velocity of ball does not change even on entering water. If viscosity of water is `eta` the value of h is given byA. `(2)/(9) r^(2)((l-rho)/(eta))g`B. `(2)/(81)r^(2)((rho-1)/(eta))g`C. `(2)/(81)r^(4)((rho -1)/(eta))^(2)g`D. `(2)/(9)r^(4)((rho -1)/(eta))^(2)g` |
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Answer» Correct Answer - C Velocity of ball when it strikes the water surface `v=sqrt(2gh)" "…..(i)` Terminal velocity of ball inside the water `v=(2)/(9)r^(2)g((rho-1)/(eta))" "……(ii)` Equating (i) and (ii) we get `sqrt(2gh)=(2)/(9) (r^(2)g)/(eta) (rho-1) implies h=(2)/(81) r^(4) ((rho-1)/(eta))^(2)g` |
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