A bomb of mass 30 kg at rest explodes into two pieces of

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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 ms^–1. The kinetic energy of the other mass is

1. 324 J
2. 486 J
3. 256 J
4. 524 J

Correct Option: B

From conservation of linear momentum m₁v₁ + m₂v₂ = 0

v₂ =			-m₁		v₁ =		-18		6 = - 9 ms^-1
			m₂				12

K.E. =	1	m₁v₂² +	1	× 12 × 9² = 486 J
	2		2