Q4.94: a man runs as fast as he can along a moving sidewalk from one end to the other, taking 3.0 s. he then runs as fast as he can back along the moving sidewalk to his starting point, taking 15 s. what is the ratio of the sidewalk’s speed to the man’s running speed?

Explanation:

Given

Man takes 3 s while running along the sidewalk

and 15 s while running opposite to sidewalk

Let the speed of man and sidewalk be v and v_0 and distance between the two endpoints of sidewalk is x

Now ----------1

Also ----------2

Divide 1 & 2

this is poiselle's equation from fluid mechanic in physics. mech eng