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(This is a question from DC Pandey.Sir,please explain in detail with diagram).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 another in time t .The speed of the plank relarive to the ground,while man was moving ,is Ans-lm/t(m+M)

(This is a question from DC Pandey.Sir,please explain in detail with diagram).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 another in time t .The speed of the plank relarive to the ground,while man was moving ,is
Ans-lm/t(m+M)

Grade:12th pass

1 Answers

Arun
25750 Points
5 years ago
Dear student
 
Let the distance moved by the plank be x.
So the distance that the man will move is L - x.
Applying Conservation of Linear Momentum,
Mx = m(L - x)
Mx = mL - mx
Mx + mx = mL
x(M + m) = mL
x = mL / (M + m)
Distance moved by the plank in T seconds is mL/( M + m).
Speed = Distance ÷ Time
Speed = mL/ [ (M + m)T]

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