Question

Man whose mass is 50 kg runs up a hill raising himself vertically 10 m in 20 seconds of time.Calculate the power used in climbing those stairs.(g=10m /s2)​

Answer 1

Answer:

Given that ,

A man whose mass is 50kg climbs up 30 steps of a stair in 30s

each step is 20 cm high

Height at 30 steps , h=30×0.2=6 m

Change in potential energy , =mgh=50×10×6=3000 J

So, Work done by the man , W=3000 J

$Power used , p = \frac{w}{t} = \frac{3000}{30} = 100w$

Answer 2

Answer:

Power = Work/Time

Work= Force × Displacement

Force = Mass×Acceleration due to gravity

Force= 50×10 = 500N

Work = 500×10 = 5000J

Power = 5000/20 = 250 W (Ans)