Levers

SW2.1 Understand that generally levers are force mulitpliers that can lift heavy loads.

Every time a lever is used, you should be able to identify where the "load" is, where the "effort" is being placed and where the lever is being turned around (also called the "fulcrum" or "pivot point")

Class 1 Lever

Here the load is placed at one end of the lever and the effort at the other end.

The fulcrum can be placed anywhere along the lever.

The Trebuchet was an ancient kind of weapon that used this principle. Go here to see how to make one.

This is a video of people who had a Trebuchet, a piano and too much time on their hands:

Other examples: scissors, crowbars and see-saws.

Class 2 Lever

Here the effort is focussed at one end and the fulcrum is at the other.

The load can be placed anywhere along the lever.

Examples: wheelbarrow.

Here is a video - hold on to your jaws!

SW2.2 Calculate mechanical advantage in levers.

For levers, mechanical advantage is either:

Load / effort (both measured in Newtons)

OR

Distance of effort from fulcrum / distance of load from fulcrum (both measured in metres)

SW2.3 Understand that class 3 levers are used to multiply speed.

Class 3 Lever

Here the have the fulcrum at one end, the load is at the other end and the effort is focussed somewhere in the middle. As a result of little effort the object can be moved at great speed.

Examples: bats and racquets, our arm lifting an object, chopsticks and fishing rods.

They're back - an attempt to explain third class levers