Question

A boy uses a single fixed pulley to lift a load of $50$ Kgf to some height. another boy uses a single movable pulley to lift the same load to the same height. Compare the effort applied by them. Give a reason to support your answer.

Answer 1

Load to be lifted $F_{load}=50kgf$

Case 1 : Fixed pulley is used.

MA for single fixed pulley $MA=1$

Thus effort applied by the boy $F_{effort}=\frac{F_{load}}{MA}=\frac{50}{1}=50Kgf$

Case 2 : Movable pulley is used.

MA for movable pulley $MA=2$

Thus effort applied by the boy $F_{effort}=\frac{F_{load}}{MA}=\frac{50}{2}=25Kgf$

So, effort to be applied by the boy is less in case when he used a movable pulley because $MA$ for a movable pulley is greater than $1$.