Question

A bullet of mass m moving with a velocity v stikes a wooden block of mass M and gets embedded in the block which was initially at rest. The final speed of the system is?

Answer 1

Initial momentum of system , p

1

=mv

Let V be the velocity of composite system

Final momentum os system , p

2

=(m+M)V

By conservation of momentum,

mv=(m+M)V

∴V=

m+M

mv

Kinetic energy of composite block, K=

2

1

(M+m)V

2

=

2

1

(M+m)(

m+M

mv

)

2

=

2

1

mv

2

×

m+M

m