Question

a) A boy of mass of 50kg runs up a staircase of 45 steps in 9s. If the height of each step is 15 cm,

find his power.


b) Define 1 watt of power​

Answer 1

Answer:

Given mass of body

(m)=

50kg

h= 45× 15= 675cm= 6.75m

δ=

10m

t= 9s

Potential energy

=

mgh

=

(50×10×6.75)5

= 33755

Power of the body =

Time

Potentialenergy

=9

3375

=375W

Answer 2

Explanation:

since, each step of stair case denotes 15cm

so, total height (h) of 45 step = 45*15=675cm or 6.75m

work done by the boy w=mg*h

=50*10*6.75

w=3375 joule

we know that,

power(p)=workdone(w)/time taken(t)

power=3375/9 js-1

power = 375 js-1