Question

A block of mass m slides with velocity v on a frictionless horizontal surface and another block of mass 3m is at rest. The velocity of centre of mass of system of two block is
A) v/5
B) v/4
C) 5v/2
D) 4v/5​

Answer 1

Answer:

The magnitude of velocity will be the same but the direction will be opposite.

Explanation:

The energy stored in the spring exists in the form of the potential energy and it is given as:

PE=  

2

1

​

kx  

2

 

When the block is left from maximum compression, the potential energy gets converted into kinetic energy of the block.

KE=  

2

1

​

mv  

2

 

At maximum compression

KE=PE

∴  

2

1

​

kx  

2

=  

2

1

​

mv  

2

 

⇒x=  

k

m

​

 

​

v

The magnitude of velocity will be the same but the direction will be opposite.