Question

A man of mass 60 kg runs up a flight of 30 steps in 15 sec. If each step is 20 cm high calculate the power developed by man ( take g = 10 m / sec2

Answer 1

As we know f=mg
f=60kg*10m/s2
f=600kg m/s2
f=600N
So,
The formula of work is
W=f.s
W=600N.s....1
S=30*20=600cm
From...1
W=f.s
W=600N.600cm
W=600N.6m
W=3600N.m
W=3600j

Now we need to find the power
As the formula of power is
P=w/t
P=3600j/15seconds
P=240j/seconds (1j/second=1watt)
P=240watts

Answer 2

Hey.

each step = 20cm =0.2 m
so total height = 30×0.2=6m

time =15 sec
so, v = 6/15=2/5=0.4 m/s

so, KE= 1/2 ×60×0.4×0.4 =4.8J

and PE =60×10×6=3600 j

so, total energy = 3604.8 J
so, power = 3604.8/15 =240.32 Watt

Thanks.