Final answer:
When you increase the number of pulleys used to lift a load, it increases the mechanical advantage of the pulley system, reducing the force required. This allows you to lift heavier loads with less force.
Step-by-step explanation:
This means that you can lift the same load with less effort because the force applied is multiplied. For instance, a pulley system with two cables attached to the load has a mechanical advantage of 2, effectively allowing the 2T force (where T is the tension in the cable) to lift the load. Similarly, adding more pulleys increases this effect; a system with three pulleys has an MA of 3, and one with four has an MA of 4. Each additional rope increases the mechanical advantage nearly by 1, as long as the pulleys are frictionless and each attachment applies an external force in approximately the same direction.
For example, if you have a single pulley with a load of 100 Newtons, you would need to apply a force of 100 Newtons to lift the load. However, if you have a system with two pulleys, the force required to lift the load would be only 50 Newtons. Each additional pulley further reduces the force required.
Therefore, increasing the number of pulleys in a system allows you to lift heavier loads with less force.