Question

What is a movable pulley? How it is different from a fixed pulley?

Answer 1

1. A fixed pulley can rotate freely about a fixed axis.
2. In a single fixed pulley, mechanical advantage is unity. It means an equal amount of effort is needed to lift any load.
3. However, in practice due to friction amount of effort required is little more than the amount of load.
4. Whereas, a movable pulley rotates freely about the axis that itself changes its position.
5. A single movable pulley needs only half of the amount of load as effort. In a single moved pulley, mechanical advantage is two.
6. For example, the effort needed to lift a 100 kgf load from a single frictionless movable pulley would be 50 kgf.