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. The ratio of the two effort is:

1. 1:2
2. 2:1
3. 1:1
4. none of these

2:1

Reason — We know that in case of a single fixed pulley, the effort applied is equal to the load.

Hence,

$E_f = L \\[0.5em]$

In the case of a single movable pulley the effort needed to lift a load is equal to half the load.

$E$m = \dfrac{L}{2} \\[1em] Em = \dfrac{50 \text{ kgf}}{2} \\[1em] \Rightarrow E_m = 25\text{ kgf} \\[1em]

Hence, the ratio of efforts applied by the respective pulley is

$\dfrac{E$f}{Em} = \dfrac{2}{1} \\[0.5em]

Therefore, E_f : E_m = 2 : 1