How do pulleys work?

Answer

A pulley works by changing the direction that force must be applied to lift an object against gravity. Other, more complex, systems use multiple pulleys to reduce the amount of force that must be applied.

A simple pulley consists of a single wheel and a rope. Instead of needing to lift an object by picking it up off the ground, a pulley system allows the object to be lifted by merely pulling on the rope. Humans using pulley systems can use their own body weight to counteract the weight of the object, making lifting easier.

A more complex system, such as a block and tackle, makes lifting easier by using multiple pulleys. Usually, these pulleys consist of a rope wound around two axles multiple times. As the rope is pulled, the lower axle and the upper axle are slowly brought together. The number of times the rope is wound around each axle is what determines the rope's tension and, friction notwithstanding, the amount of force required to lift an object. However, energy is always conserved. Someone using a pulley system to use only 100 pounds of force to lift a 400-pound object must pull four times as much rope, expending the same amount of energy as it would take to lift a 100-pound object four times as far.

Q&A Related to "How do pulleys work?"
Fixed pulley wheels don't move up and down but are fastened to a fixed structure, like the top of a flagpole. The load arm (lift up) and effort arm (pull down) of the cable are equal
http://www.ehow.com/facts_7355522_type-pulley-flag...
Gears Are Relevant To Pulleys Because Gears Turn Into Circles So Do Pulleys The Difference Between A Gear And A Pulley Is. A Pulley : Pulley Has Strings To Hold On One Goes Up And
http://wiki.answers.com/Q/What_pulleys_are_there
1. Detach all objects from the pulley system and remove the rope. 2. Hang a new pulley next to or beneath the old pulley. The location doesn't matter so long as they sit close enough
http://www.ehow.com/how_11404438_pulley-spin-faste...
1. Secure the pump to the workshop table with a vise or other workshop clamp. Locate the part of the power steering pulley puller. 2. Insert the puller bolt into the center of the
http://www.ehow.com/how_7506784_replace-power-stee...
Explore this Topic
A pulley works by a rope wrapping around a device so two sides hang down, you apply force to one side and it pulls on the other side allow you to lift something ...
A pulley is one of the best of the 'simple machines'. The way it wors is using a block and tackle, it allows you to use half the force needed to pick something ...
The double pulley system works by transferring energy to make it easier to move heavy objects by the use of two pulleys. A rope or belt is placed around a wheel, ...
About -  Privacy -  Careers -  Ask Blog -  Mobile -  Help -  Feedback  -  Sitemap  © 2014 Ask.com