Question

An input for of 80 N is used to lift an object weighing 240 N with a system of pulleys. How far must the rope around the pulleys be pulled in order to lift the object a distance of 1.4 m?

Answer 1

4.2 m

Step-by-step explanation:

Note: If energy is conserved, i.e no work is done against friction

Work input = work output.

Work output = Force output × distance,

Work input = force input × distance moved moved.

Therefore,

input force×distance moved = output force × distance moved........................Equation 1

Given: input force = 80 N, output force = 240 N, output distance = 1.4 m

Let input distance = d

Substitute into equation 1

80×d = 240×1.4

80d = 336

d = 336/80

d = 4.2 m.

Thus the rope around the pulley must be pulled 4.2 m