A bomb of mass 12kg at rest explodes into two pieces of masses 4 kg and 8 kg, the velocity of mass 8kg is 5 m/s. the kinetic energy of mass 4 kg is:
Correct answer: C. 200 J
- A. 100 J
- B. 150 J
- C. 200 J
- D. 192 J
Explanation
Momentum conservation: 0 = 8×5 + 4 v4 ⇒ v4 = −(8×5)/4 = −10 m/s (opposite direction). K.E. of 4 kg = ½×4×10² = 200 J. So option C is correct.
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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