1. Characteristics of Levers

2. Goals of the Lesson Identify class 1, 2, and 3, levers
Apply mathematical formulas to find mechanical advantage and moments
Design a lever to achieve balance while applying a selected force with a predetermined moment arm.
Incorporate levers in a mechanical basketball player project.

3. Levers Babysitting 6 year old sister At playground
She asks you to ride the teeter-totter.
What can you do so that you can achieve a balance (neither person moving up or down)?

4. Levers Likely adjust position until balance is achieved
Many system designs require
Mathematical model solutions
Testing

5. Mechanical Basketball
Requires
Basic understanding of levers
Mathematical modeling tools

6. Parts of a Lever The Fulcrum (Pivot Point) Effort Force Load Force
When Fulcrum, Load, or Effort are moved
There are changes
In how high the Load is lifted
How much Effort is required to move the load

7. Classes of Levers Levers are simple machines
Allows you to change
Direction of motion
Amount of effort needed to move a load a given distance
There are 3 classes of levers

8. Class 1 Lever Fulcrum Teeter-Totter
Located between EFFORT FORCE and LOAD FORCE
Teeter-Totter

9. Class 2
The fulcrum is at one end, the effort is at the opposite end, and the load is between them.
Moves the load same direction as the effort moves.
Wheelbarrow

10. Class 3
Is used when desirable to have the Load move further than the Effort with the fulcrum at the opposite end.
Lower arm

11. Mathematical Formulas
We use mathematical formulas
To accurately predict if a Load will move with a given Effort
How much Effort will be required to move a given Load
Determine the optimal points along the beam for placement of fulcrums, Loads, and Efforts

12. Moment Shows how the forces balance with each other
Identify the effect of both force and distance
Moment (also known as torque) = force x distance
(distance means the distance from the fulcrum)

13. If we know the Effort force is 100 pounds and we are looking for the Load force (lf) that will keep the lever in equilibrium, the equation is set up as:

14. Mechanical Advantage
Factor that the Effort force is multiplied by to create the Load force

15. Mechanical Advantage

16. Mechanical Advantage and Moment
Our examples only show Class 1 Levers
When evaluating Class 2 and Class 3 levers
It is important to note that we still measure both of these distances or lengths from the fulcrum
Even though they overlap each other for part of their lengths.

17. Summary How many classes of levers are there?3
Which class has the effort placed between the fulcrum and the load?
Class 3
How can we accurately evaluate the effectiveness of a lever for a given use?
By experimenting with it and applying the two mathematical formulas)