Question

At the corner of the campus there is a walking path with a big staircase. There are 126 steps that are an average height of 15 cm (for each step). A 135 lbs. woman climbs the stairs. She starts from rest and is moving 1.2 m/s at the top (a walking pace). How much work does she do?

Answer 1

In the above given question, we have

weight=135 lbs or 61.23 kg

no of steps 126 with avg height 0.15m,it means total height is 126*0.15= 18.9m

moving velocity=1.2m/sec

there are two different amount of wok done we have to calculate,

.potential work and kinetic work (because of motion)

so potential work =m*g*h= 61.23*9.81*18.9= 11.35 kj (kilo jule)

and kinetic work done=1/2*m*v²= 0.5*61.23*1.2*1.2= 44.08 j

so total work done=P.E+K.E

                          =11.35 KJ + 44.08 J

                         = 11.39 KJ   ans