Question

What object A collides with object B and bounces back its final momentum is?

Answer 1

Explanation :
`p_f=-p_i`

Momentum of a body is defined as the product of its mass and velocity.

i.e.
`p=m* v`

So, when an object is moving, it has momentum.

If
`m_1` and
`m_2` are the masses of objects A and B and
`u_1\ and\ u_2` are their initial velocities. so, their initial momentum will be:

`p_i=m_1u_1+m_2u_2`

If after collision it bounces back with same velocities, then final momentum becomes:

`p_f=-m_1u_1+(-m_2u_2)`

-ve sign shows that the motion is in opposite direction.

so,
`p_f=-(m_1u_1+m_2u_2)`

or
`p_f=-p_i`

Hence, its final momentum is in opposite direction of initial momentum.