A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 m/s. The kinetic energy of other mass is

Options

A. 324J
B. 486J
C. 256J
D. 524J

Answer

B

Explanation

According to the law of conservation of angular,momentum,
`30 x 0 = 18 xx 6+12 xx v rArr` v=-9m/s,
Negative sign indicates that both fragments move in the opposite directions.
K.E. of 12kg= `1/2mv^2` = `1/2xx12xx81=486 J`