Question

a bullet in motion hits and get embedded in a solid resting on a frictionless table. what is conserved ?

a) kineitc energy only (how?)

b) momentum only(how?)

Answer 1

When a bullet of mass m moving with a velocity v gets embedded in a block of mass m',the block will acquire a velocity v', and mass of block along with the embedded bullet will become=m+m'

We see that mv=(m+m')v'

p=p' (since momentum p=mass x velocity)

Hence momentum is conserved.