Question

A ball with a mass of `5 kg` moving at `4 m/s` hits a still ball with a mass of `7 kg`. If the first ball stops moving, how fast is the second ball moving?

Answer 1

The velocity of the second ball is `=2.86ms^-1`

Explanation:

We have conservation of momentum

`m_1u_1+m_2u_2=m_1v_1+m_2v_2`

`(5xx4)+(7xx0)=(5xx0)+(7xxv_2)`

`7v_2=5*4=20`

`v_2=20/7=2.86ms^-1`