Question

A 500 kg boat is 9 m long and is floating without

motion on still water. A man of mass 100 kg is at

one end and move to other end of boat and stops.

The displacement of boat is

(1) 1.5 m in the direction of displacement of man

(2) 0.75 m in the direction of displacement of man

(3) 1.5 m in the direction opposite to displacement

of man

(4) 0.75 m in the direction opposite to displacement

of man

​

Answer 1

Answer:

As there is no external force, the center of mass of the boat+man system remains at the same position. The displacement of boat would be in opposite direction to that of the man, to maintain same position for CoM.

Let the displacement of boat be x, in direction opposite to the displacement of man.

So net displacement of man is (9−x)

So, M

man

×(9−x)=M

boat

×x

⟹100(9−x)=500x⟹x=900/600=1.5m