Question

A body of mass `4 kg` moving with velocity `12 m//s` collides with another body of mass `6 kg` at rest. If two bodies stick together after collision , then the loss of kinetic energy of system is
A. zero
B. `288 J`
C. `172.8 J`
D. `144 J`

Answer 1

Correct Answer - C
Loss in `K.E. = (1)/(2) (m_(1) m_(2))/(m_(1) + m_(2)) (u_(1) - u_(2))^(2)`
`= (1)/(2) . (4 xx 6)/( 4 + 6) ( 12 - 0)^(2) = 172.8 J`