The diagram shows a flight of stairs. How much useful work is done by a person weighing 600 N when climbing the stairs?
Correct answer: B. 1800 J
- A. 120 J
- B. 1800 J
- C. 2400 J
- D. 3000 J
Explanation
By conservation of energy, Useful work done = gain in gravitational potential energy = mgh = (600 N) (3 m)= 1800 J
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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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