# Understanding the Efficiency of Two-Wheel Compound Pulley Systems

## How does a two-wheel compound pulley system affect the force needed to lift an object?

Alan will use a two-wheel compound pulley to lift a crate from the floor of his garage to a storage shelf. The shelf is 5 meters above the floor. Alan pulls meters of the rope to lift the crate. Which statement is correct?

Final answer: Alan uses a two-wheel compound pulley to lift a crate. Ideally, the force required is reduced to half of the load's weight in such a system, so the correct answer is D.

## Explanation

In the given scenario, Alan is using a two-wheel compound pulley system to lift a crate to a storage shelf. Such systems are mechanical devices used to reduce the force needed to lift a load. In an ideal two-wheel pulley system, the required force is theoretically reduced to half of the weight of the object being lifted.

Therefore, the correct statement would be D. Alan uses half of the force he would have needed without the compound pulley. The force is shared between two ropes in the parallel sections of the pulley system. So, each rope carries half of the total weight, reducing the total force required.

By understanding the efficiency of two-wheel compound pulley systems, one can optimize the force required to lift objects and make lifting tasks easier and more efficient.