A mass of 12 kg at rest explodes into two pieces of masses 4 kg and 8 kg which move in opposite directions. If the velocity of 8 kg piece is 6 ms' then the kinetic energy of the other piece is (in Joule)

Options

A. 64
B. 128
C. 144
D. 288

Answer

d

Explanation

According to law of Conservation of momentum
` m_(1)u_(1)+m_(2) u_(2)=m_(1)v_(1)+m_(2)v_(2)`
`mv=m_(1)v_(1)+m_(2)v_(2)`
`12xx0=8xx6+4(-v_(2))`
`v_(2) =12m//s`
K.E of the other piece, `K.E_(2)=1/2m_(2)v^(2)_(2)`
`1/2 xx4(12)^(2)=288`