1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

# A child is standing at one end of a long trolley moving with a speed v on a smooth horizontal track. If the child starts running towards the other end of the trolley with a speed u, the centre of mass of the system (trolley + child) will move with a speed

A

Zero

No worries! We‘ve got your back. Try BYJU‘S free classes today!
B

(v + u)

No worries! We‘ve got your back. Try BYJU‘S free classes today!
C

(v - u)

No worries! We‘ve got your back. Try BYJU‘S free classes today!
D

v

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

## The correct option is D v The speed of the centre of mass of a system can change only if a net external force acts on it. The forces involved (such as the action and reaction and frictional forces), when the child runs on the trolley, are internal to the (trolley + child) system. The speed of the centre of mass of the system will remain unchanged, i.e., equal to v. Hence, the correct choice is (d).

Suggest Corrections
121
Join BYJU'S Learning Program
Related Videos
Centre of Mass in Galileo's World
PHYSICS
Watch in App
Join BYJU'S Learning Program