Question

A pulley system is used to lift a load of 350 kgf through a vertical height of [4] 30 m. The effort required is 100 kgf in the downward direction.

Answer 1

The mechanical advantage is 3.5, Efficiency is 87.5, Work done by effort is 1875 Joules  and the 3.75 m

Explanation:

Given data:

• V-R = 4
• Load = 150 Kg
• dL = 20 m
• Effort = 50 Kg

dE = ?

Solution:

V = R = dE / dL

4 = dE / 20

dE = 80 m

Since V = R ( no. of pulley is a system of n pulleys.)

Number of pulleys = 4

Mechanical advantage = 175/50 = 3.5

Efficiency = (mechanical advantage/velocity ratio)×100  = (3.5/4)×100 = 87.5

Work done by effort = 50×10×(15/4)= 1875 Joules

Distance moved by effort  = 15/4 = 3.75 m

Thus the mechanical advantage is 3.5, Efficiency is 87.5, Work done by effort is 1875 Joules  and the 3.75 m