Question

A boy of mass 36 kg moves from one end to other end of a boat of mass 72 kg on still water. If the length of the boat is 2.7m, the displacement of the boat is
(A) 2.7 m
(B) 1.35m
(C) 5.4m
(D) 0.9m​

Answer 1

Given :-

• A boy of mass 36 kg moves from one end up to other end of a boat of mass 72 kg on still water length of the  boat is 2.7m

To Find :-

•  the displacement of the boat  
• (A) 2.7 m

• (B) 1.35m

• (C) 5.4m

• (D) 0.9m

Solution:-

• (M + m)d  = m.L
• => d = m . L / ( M + m)
• m = mass of man  = 36 kg
• L = length of boat ( distance covered by Man) = 2.7 m
• M = Mass of Boat = 72 kg
• d = displacement of boat

• => d =  36 ( 2.7) / (72 + 36)
• => d = 36 ( 2.7) /108
• => d = 2.7/3
• => d = 0.9 m

the displacement of the boat is 0.9 m

=> option D is correct