Question

Q. Two boys enter a running escalator at the ground floor in a shopping mall and they do some fun on it. The first boy repeatedly follows p1=1step up and then q1=2 step down whereas the second boy repeatedly follows p2= 2steps up and then q2= 1step down. Both of them move relative to the escalator with speed Vr = 50cm/s. If the first boy takes 250s and second boy takes 50s to reach the first floor, how fast is the escalator running???

Answer 1

Let the speed of escalator be x.

speed*time=displacement

and displacement covered by both of them is from ground floor to first floor

therefore,

(50-x)250=(50+x)50.

12500-250x=2500+50x

-200x=-10000

x=(50cm/s)/2.

=25cm/s.