Our pulleys and gears unit test will be Tuesday, October 29th. Below are some key concepts to help prepare for the test.
A pulley is a wheel with a groove in it, and a rope or chain passes over the pulley.
There are two main types of pulleys; a fixed pulley and a moveable pulley. *Be able to recognize them.
A fixed pulley does not make it easier to lift a load, but it does change the direction of the force.
A moveable pulley makes it easier to lift the load (you only need half the force), but it does not change the direction of the force.
When pulleys are combined we call them a pulley system.
Pulleys are used to:
Change the direction of force
Make it easier to lift something
The thing that is lifted by a pulley is called a load.
The force used to lift the load is called the effort.
Mechanical advantage tells how much easier the system makes it to lift the load.
A flagpole or a crane are examples of things that use pulleys.
Gears are normally round, wheel like discs that are covered in teeth.
Gears rotate on an axle.
When gears are in contact they are said to be “meshed”.
A gear can be used to transfer force and motion, it can be used to change the direction and speed of motion.
There are four types of gears we studied; spur gears, bevel gears, worm gears and a rack and pinion.
*Be able to recognize them.
When three or more gears are combined we call them a gear train.
When gears are meshed the number of times they turn depends on the number of teeth.
When gears are meshed the speed with which they turn depends on the number of teeth.
An eggbeater and a clock are examples of things that use gears.