Question

What does the law of conservation of momentum mean?

Answer 1

It means that in a collision (even an inelastic collision) total momentum after the collision is the same as total momentum before the collision.

Explanation:

Momentum before = momentum after
`m_1*u_1 + m_2*u_2 = m_1*v_1 + m_2*v_2`
where the u terms are initial velocity and the v terms are velocity after the collision.

If the 2 become stuck together, then `v_1 = v_2` so we can simplify the above formula to

`m_1*u_1 + m_2*u_2 = (m_1 + m_2)*v`

I hope this helps,
Steve