question_answer

Two persons of masses 55 kg and 65 kg respectively, are at the opposite ends of a boat. The length of the boat is 3.0 m and weighs 100 kg. The 55 kg man walks up to the 65 kg man and sits with him. If the boat is in still water the centre of mass of the system shifts by:

A) 3.0m    

B) 2.3m

C) zero      

D) 0.75m

Correct Answer: C

Solution :

[c]  There is no external force so centre of mass of the system will not shift.