A mass of 10g moving with velocity of 100 cm/s strikes a pendulum bob of mass 10g. The two masses stick together. The maximum height reached by the system now is (g = 10 m/s2):
Correct answer: D. 1.25 cm
- A. Zero
- B. 2.5 cm
- C. 5 cm
- D. 1.25 cm
Explanation
Initially mass 10 gm moves with velocity 100cm/s∴ Initial momentum = 10 × 100 = 1000 gm × cm/secAfter collision system moves with velocity vsys thenFinal momentum = (10 + 10) × vsysBy applying the conservation of momentum1000 = 20 × vsys ⇒ vsys = 50 cm/sIf system rises up to height h thenh = vsys² / 2g = (50 × 50) / (2 × 1000) = 2500 / 2000 = 1.25 cm
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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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