Two blocks of masses 10 kg and 4 kg are connected by a spring of negligible mass and placed on a frictionless horizontal surface. An impulse gives a velocity of `14 m//s` to the heavier block in the direction of the lighter block. The velocity of the centre of mass is

Options

A. `30 m//s`
B. `20 m//s`
C. `10 m//s`
D. `5 m//s`

Answer

C

Explanation

( c) `Mv_(cm) = m_1 v_1 + m_2 v_2`
`v_(cm) = (4 xx 0 + 10 xx 14)/(14) rArr v_(cm) = 10 m//s`.