Question

1. A 50 kg person stands on a 25 kg platform. He pulls massless rope which is attached to the platform via the frictionless, massless pulleys as shown in the figure. The platform moves upwards at a steady velocity if the force with which the person pulls the rope is

Answer 1

From the data given,

Weight of the person, w1 = 50kgs.

Weight of the platform, w2 = 25kgs.

If the platforms moves upwards with a steady state,  

The force, 3F = (w1+w2)g

Therefore,

3F = (50+25)g

Taking  g = 10 m/ s^2,

3F = 750

The force with which the person pulls the rope = 250N.