# pulley

## what is a pulley

A pulley is a simple machine that consists of a rope and grooved wheel. The rope fits into the groove in the wheel, and pulling on the rope turns the wheel. Pulleys are generally used to lift objects, especially heavy objects. The object lifted by a pulley is called the load. The force applied to the pulley is called the effort. Q: Can you guess what the pulley pictured above is used for? A: The pulley is used to lift heavy buckets full of water out of the well.

## types of pulleys

Some pulleys are attached to a beam or other secure surface and remain fixed in place. They are called fixed pulleys. Other pulleys are attached to the object being moved and are moveable themselves. They are called moveable pulleys. Sometimes, fixed and moveable pulleys are used together. They make up a compound pulley. The three types of pulleys are compared in the Table 1.1. Q: Which type of pulley is the old pulley in the opening image? A: The old pulley is a single fixed pulley. It is securely attached to the beam above it. Type of Pulley How It Works Example Single fixed pul- ley Flagpole pulley No. of Rope Segments Pulling Up 1 Ideal Mechani- cal Advantage 1 Change Direction Force? yes Single moveable pulley Zip-line pulley 2 2 no Compound pulley (fixed & moveable pulleys) Crane pulley 2 2 varies in of

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

a flagpole pulley is a

``````-->  a) fixed pulley.

b) moveable pulley.

c) compound pulley.

d) none of the above
``````

the ideal mechanical advantage of a pulley is equal to the number of rope segments pulling up on the load.

``````-->  a. true

b. false
``````

a moveable pulley changes the direction of the input force.

``````a. true

-->  b. false
``````

a zip-line pulley is a moveable pulley.

``````-->  a. true

b. false
``````

which type(s) of pulley can have a mechanical advantage greater than 2?

``````a) fixed pulley

b) moveable pulley

-->  c) compound pulley

d) two of the above
``````

all pulleys increase the force applied to the pulley.

``````a. true

-->  b. false
``````

## diagram questions

No diagram questions associated with this lesson