Question

A body of mass 2kg moving with velocity of 6m/s collides with a stationary object of mass 0.5kg. If the two bodies move together after the impact, calculate their common velocity.

Answer 1

Given:

$m_1=2\:\rm kg$, $m_2=0.5\:\rm kg$

$v_1=6\:{\rm m/s},\quad v_2=0$

The law of conservation of momentum gives

$$m_1v_1+m_2v_2=(m_1+m_2)u$$ $$u=\frac{m_1v_1}{m_1+m_2}=\frac{2*6}{2+0.5}=4.8\;\rm m/s$$