What Is a Pulley?
A pulley is a simple machine. It is a wheel with a groove, and a rope runs over the wheel. When we pull one end of the rope down, the load on the other end goes up.
How a Pulley Helps
A pulley makes it easier to lift a load. Instead of pulling a heavy load straight up, we can pull the rope down, which is easier because we can use our own body weight. A pulley also lets us lift a load to a high place, like raising a flag up a pole or lifting a pail of water from a well.
Key idea
A pulley is a wheel with a rope that helps us lift a load more easily by pulling the rope downwards.
Example
To raise the school flag, we pull the rope down. The pulley at the top of the pole lets the flag go up easily.