A man of mass m moves with a constant speed on a plank of mass M and length l kept initially at rest on a frictionless horizontal surface, from one end to the other in time t. The speed of the plank relative to grounud while man is moving, isA. `l/t(M/m)`B. `l/t(m/(m+M))`C. `l/t(M/(M +m))`D. None of these

A man of mass m moves with a constant speed on a plank of mass M and l

1.	A man of mass m moves with a constant speed on a plank of mass M and length l kept initially at rest on a frictionless horizontal surface, from one end to the other in time t. The speed of the plank relative to grounud while man is moving, isA. `l/t(M/m)`B. `l/t(m/(m+M))`C. `l/t(M/(M +m))`D. None of these
Answer» Correct Answer - B `v_(r) = l/t`, Now , `m(v_(r)-v) = Mv` (v= speed of plank) `v=(mv_(r)/(M +m)` = l/t(m/(M +m)`

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