What is a pulley?

A pulley is a device used to lift heavy objects. It is made with a cable and a wheel of different sizes. Here again, the law ‘Work = Force x Distance’ is applicable as in the case of serpentines. Here ‘distance’ means the length of the cable. The cable is wound around the wheels. The more the number of wheels, the smaller the force to be applied. We can find such pulleys on sailing ships for hoisting the sail. They are also used at construction sites to lift beams or other construction material. Earlier, pulleys were used to put heavy ship boxes in storage spaces high above the ground.