Q.

Which of the following is/are correct?

Moderate

Unlock the Full Solution and Master the Concept

Get a detailed solution and exclusive access to our masterclass to ensure you never miss a concept

By Expert Faculty of Sri Chaitanya

If centre of mass of three particles is at rest and it is known that two of them are moving along different lines, then the third particle must also be moving.

If centre of mass remains at rest, then net work done by the forces acting on the system must be zero.

If centre of mass remains at rest, then the net external force must be zero.

If speed of centre of mass is changing, then there must be some net work being done on the system outside.

answer is 1,2,3.

(Detailed Solution Below)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

1. As ΣP→=0 and P→1+P→2≠0, P→3 cannot be zero.2. For any system of two or more than two particles, KE can change due to work done by internal forces while the centre of mass remains at rest 3. a→CM=0⇒ΣF→ext=04. It is possible to have changing speed of CM without any work done by ext. forces on the system. When a person accelerates himself on a rough horizontal surface without any slipping between his shoes and ground, work done by friction, normal reaction and weight all are zero but speed of centre of mass changes.

Choose your Grade and Exam

Connect with our

Expert Counsellors

access to India's best teachers with a record of producing top rankers year on year.

+91

We will send a verification code via OTP.