Question

Two bodies of masses 10kg and 4kg are moving in opposite directions with the same velocity of 5 meter per seconds .if they collide and stick together after the impact,calculate their velocity

Answer 1

The law of conservation of momentum says

$$m_1v_1+m_2v_2=(m_1+m_2)u$$

The final velocity

$$u=\frac{m_1v_1+m_2v_2}{m_1+m_2}$$

$$u=\frac{10*5+4*(-5)}{10+4}=2.14\:\rm m/s$$