Question

A body of mass `2 kg` makes an elastic head - on collision another body at rest and continues to move in the original direction with one fourth of its original speed . The mass of the second body which collides with the first body is
A. `2 kg`
B. `1.2 kg`
C. `3 kg`
D. `1.5 kg`

Answer 1

Correct Answer - B
`2 v_(0) = (2v_(0))/(4) + mv rArr mv = (3v_(0))/(2)` (i)
`(v_(0))/(4) + v_(0) = v + 0 rArr v = (5v_(0))/(4)` (ii)
`mv = ( 3v_(0))/(4) rArr m xx (5v_(0))/(4) = ( 3v_(0))/(2)`
`m = 1.2 kg`