A man M1 of mass 80 kg runs up a staircase in 15 S. Another man M2 also of mass 80 kg runs up the samestaircase in 20 S. The ratio of the power developed by them will be:
Correct answer: B. 4/3
- A. 1
- B. 4/3
- C. 16/9
- D. None of these
Explanation
W = 80Nm = 80 / gt = 15 secP = W / t = mgh / t1st manW = mgh= 80 × 9.8 × h= 784 hPower₁ = 784 h / 15m₂ = 80 kgSame heightt = 20 sW = 80 × 9.8 × h= 784 hPower₂ = 784 h / 20Ratios of PowersP₁ / P₂ = (784 h / 15) / (784 h / 20)= 20 / 15= 4 : 3
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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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