I WONDER - How Does A Pulley Work?

A pulley is a wheel with a groove for holding a rope, belt, or cable. Pulleys can change the direction of force or reduce the force needed to lift loads. They are used in systems like flagpoles and wells. Complex systems, called block and tackle, are used in machinery to lift heavy loads. The mechanical advantage increases with more pulleys.

What are complex pulley systems known as, and where are they used?

How does the mechanical advantage of a pulley system change with the number of pulleys used?