Question

A person of mass mis standing on one end of a plank
of mass Mand length L floating in water. The person
moves from one end to another and stops. Work
done by normal force is -
(1) MGL
(2) mgL
(3)
mMgL
M + m
(4) 0​

Answer 1

Explanation:

The man is on the other side of center of mass now, and ...

According to law of conservation of momentum mv = (m + M)V

or mL/t = (M + m) x (x/t)

where t is time of motion x = mL/(m+M)