Question

A ball with a mass of `1 kg` moving at `8 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

`1,143m//s`

Explanation:

The Principle of conservation of linear momentum states that in an isolated system total linear momentum is always conserved in each direction.
Application in this particular case yields :

`p_i=p_f`

`therefore (m_1v_1+m_2v_2)_i=(m_1v_1+m_2v_2)_f`

`therefore(1xx8)+(7xx0)=(1xx0)+(7xxv)`

`therefore v=8/7=1,143m//s`.