A man of mass 50kg ascends a flight of stains 5m high in 5 seconds. If acceleration due to gravity is 10ms\(^{-2}\) the power expended is
A
100w
B
200w
C
400w
D
500w
Verified Correct Answer: D.
Physical Principles & Numerical Solution
Power is the time rate of doing work
i.e power = \(\frac{\text{energy}}{\text{time}}\)
Since energy = mgH
∴ power = \(\frac{mgH}{t}\)
= \(\frac{50 \times 10 \times 5}{t}\)
= 500W
Source: Myschool Past Questions Archive (Record #46402)