question_answer

A ladder is leaned against a smooth wall and it is allowed to slip on a frictionless floor. Which figure represents the track of its centre of mass?

A)

B)

C)

D)

Correct Answer: C

Solution :

                Every physical system has associated with it a certain point whose motion characterises the motion of the whole system. When the system moves under an external force then this point moves in the same way as a single particle would move under the same external force. This point is called centre of mass. In the given case the acceleration acts in the downward direction, in the centre.