A body of mass `m_(1) ` moving with uniform velocity of 40 m/s collides with another mass `m_(2)` at rest and then the two together begin to moe wit h uniform velocity of 30 m/s. the ratio of their masses `(m_(1))/(m_(2))` is

Options

A. ` 0.75`
B. ` 1.33`
C. ` 3.0`
D. `4.0`

Answer

C

Explanation

Initial momentum of the system =` m_1 xx 40 +m_2 xx 0 `
Final momentum of the system = `( m_1+ m_2 ) xx 30 `
By the law of conservation of momentum
` m_1xx 40 +m_2 xx 0 =( m_1+m_2) xx 30 `
`rArr 40 m_1 = 30 m_2 rArr 10 m_1 = 30 m_2 = (m_1)/( m_2) = 3 `