Pulleys - Simple Machines - What are pulleys? How do pulleys work?
Welcome to Quatr.us Study Guides!

Pulleys

Clothesline pulley
Clothesline pulley

April 2016 - A pulley is really a kind of wheel, just as a screw is a kind of inclined plane. But pulleys are so important that people give them their own category. A pulley is a wheel with two raised edges so that a rope or a string will run along the wheel without coming off. It's often also called a block and tackle.

Because there are no wheels in nature, there are also no pulleys. Pulleys may have been invented by Archimedes in ancient Sicily, about 250 BC.

As with a screw, you can use a pulley in several different ways. You can use a pulley to make it easier to pull a rope, to change the direction of a force, or to get more mechanical advantage and lift something heavier than you can lift by yourself.


Khan Academy explains how to calculate mechanical
advantage for moveable pulleys

With a fixed pulley, the pulley is attached to a hook or a wall and doesn't move, like the clothesline pulley in the picture here. A fixed pulley doesn't give you any mechanical advantage, but it changes the direction of the force. For instance, you can pull down in order to lift something up, or you can pull the upper clothesline toward you in order to move the lower clothesline away from you.

With a movable pulley, you do have a mechanical advantage: you can pull with less force for a longer distance to get the same work done. You're using the pulleys to make the rope wind around longer, so you have a longer distance to pull, and need less force. This lets you lift things that would be too heavy for you without a pulley.

Movable pulleys
Learn by doing - pulleys

Bibliography and further reading about simple machines:

Machines
Physics
Quatr.us home


LIMITED TIME OFFER FOR TEACHERS: Using this article with your class? Show us your class page where you're using this article, and we'll send you a free subscription so all your students can use Quatr.us Study Guides with no distractions! (Not a teacher? Paid subscriptions are also available for just $16/year!)
Please help other teachers and students find us: link to this page from your class page.
Karen Carr is Associate Professor Emerita, Department of History, Portland State University. She holds a doctorate in Classical Art and Archaeology from the University of Michigan. Follow her on Instagram or Twitter, or buy her book, Vandals to Visigoths.
Cite this page
  • Author: K.E. Carr
  • Title:
  • Site Name: Quatr.us Study Guides
  • Publisher: Quatr.us
  • Date Published:
Did you find what you needed? Ask your teacher to link to this page so other people can use it too! Send it in and win a Quatr.us "Great Page!" award!
Sign up for more free articles and special offers in Quatr.us' weekly newsletter:
We will never share your e-mail address unless you allow us to do so. View our privacy policy. Easy unsubscribe links are provided in every email.
Comment on This Article

Does your class page honor diversity, celebrate feminism, and support people of color, LBGTQ people, and people with disabilities? Let us know, and we'll send you a Diversity Banner you can proudly display!
Looking for more?
Quatr.us is loading comments...
(Comments will appear after moderation, if they are kind and helpful. Feel free to ask questions, and we'll try to answer them.)
Cite this page
  • Carr, K.E. . Quatr.us Study Guides, . Web. 24 April, 2017
ADVERTISEMENT