What force does a pulley change when lifting a load?

A pulley primarily changes the effort force needed to lift a load by providing a mechanical advantage. When using a pulley system, the direction of the force applied can be altered, allowing the user to pull down on the rope to lift the load upwards. This makes it easier to lift heavy objects, as the effort required to overcome the load's weight can be reduced.

In essence, when using a pulley, one can lift a load with less effort compared to lifting it directly against gravity. Although other forces, such as weight and friction, play a role in the overall mechanics when using pulleys, the specific functionality of a pulley is to modify how much effort is necessary from the user, enhancing efficiency in lifting tasks.