A body P of mass 1 kg moving with a velocity of `3 ms^(-1)` along the +x direction collides head-on with a body Q of mass 2 kg at rest. The collision is elastic. After the collision

Options

A. P moves along the +x direction with a velocity of `1 ms^(-1)`
B. P moves along the-x direction with a velocity of `1 ms^(-1)`
C. Q moves along the +x direction with a velocity of `2 ms^(-1)`
D. Q moves along the-x direction with the velocity of `2 ms^(-1)`

Answer

B, C

Explanation

`v_1 = ((m_1 - m_2)/(m_1 + m_2))u_1 .....(1)`
`v_2 = (2m_1)/(m_1 + m_2) u_1 .......(2)`
Using Eq. (1) and (2) we get `v_1 = -1ms^(-1) and v_2 = +2 ms^(-1)`