What is a Pulley?
So you’ve got a heavy load, and you want to move it. You might try a simple machine that’s the basis of much modern machinery — a pulley. There are six simple machines: an inclined plane, a lever, a screw, a wedge, a wheel and axle, and a pulley. Basically, a pulley changes the direction of an applied force. Thus, for instance, you can pull on the cable of the pulley, and it will pull a weight. A pulley, which is derived from the Greek word polos, meaning axis, is a wheel with a groove. A rope, belt, or cable runs inside the groove. That mechanism can be used alone or connected with other pulleys in a pulley system. The greater the number of pulleys in the system, the less force it will take to lift an object. A block and tackle system, which is a basic pulley system, can illustrate how pulleys provides this kind of lifting advantage. Consider this: you have a 10-pound weight with a rope attached to it. To lift it up, you’ll need to exert 10 pounds of force straight up. If you have it
A pulley is a simple machine made with a rope, belt or chain wrapped around a wheel. The pulley is usually used to lift a heavy object (load). WHAT DOES A PULLEY DO? A pulley changes the direction of the force, making it easier to lift things ARE ALL PULLEYS THE SAME? No, they are not. There are three types of pulleys: *A FIXED PULLEY *A MOVABLE PULLEY and *A COMBINED PULLEY A single pulley changes the direction of the lifting force. For example, if you are lifting a heavy object with a single pulley anchored to the ceiling, you can pull down on the rope to lift the object instead of pushing up. The same amount of effort is needed as without a pulley, but it feels easier because you are pulling down.
