1. LEVERS

2. Levers are used to apply forces.
They help us to move ourselves…
or other objects.

3. The Scientific Part!

4. Parts of a lever
Within the lever are three components that we need to understand -
Fulcrum or Pivot - the point about which the lever rotates
Load or Resistance - the force applied by the lever system. Load to be moved (which includes lever itself)
Effort or Force - the force applied by the user of the lever system – the force which causes movement

5. There are three classes of levers
The class of lever is dictated by the arrangement of the 3 components:

6. 1st Class Lever The fulcrum lies between the effort and the load
e.g see-saw, crowbars

7. 2nd Class Levers Eg wheelbarrow
The load lies between the effort and the fulcrum
Eg wheelbarrow

8. 3rd Class Lever The effort lies between the load and the fulcrum
Eg tweezers & most muscles.

10. Force Arm & Resistance Arm
The distance from the fulcrum (pivot) to the point of force (effort) is called the FORCE ARM
The distance from the fulcrum (pivot) to the point of resistance is called the RESISTANCE ARM
Lever characteristics
Long resistance arm: speed and range of movement
Short resistance arm: force

11. FUNCTIONS OF LEVERS All levers have 2 functions: They either:
Increase the speed at which an object can move with a given effort.
E.g. driver as opposed to an iron in golf
Increase the resistance that can be moved with a given effort
E.g. Wheelbarrow – can lift a big weight that would not be able to lift alone

12. Mechanical advantage
If Resistance arm is longer, lever is better for force
If Resistance arm is shorter, lever is better for speed
In 2nd class levers resistance arm is always longer, therefore 2nd class levers are better for strength or force
In 3rd class levers force arm is always longer, therefore 3rd class levers are better for speed

13. The Application Part!

14. So… what happens when a golfer uses different clubs?
The longer the lever the greater the speed.
What about control?
Which is easier to control and hit straight – an iron or a driver?

15. Question
In badminton, why is it easier to teach children to hit the shuttle with a shorter racquet?

16. Debate
“Short people are stronger than taller people”