1. February 23, 2025 Do Now: Read through the Lever Lab directions and answer the first three questions Find the weight in Newtons of the gravel container by using the spring scale (that is your resistance) Homework: Study for test and finish contract project

2. First Class Second Class Third Class

3. Today Lever Lab Review last test Review Incline Plane results Kahoot

4. Six Simple Machines Inclined Plane Wedge Screw Lever Pulley Wheel & Axle

5. Mechanical Advantage

6. Terminology Where your hands are Effort Input Output DISTANCE Where the load is Load Output Resistance Input DISTANCE

7. Mechanical Advantage Effort Force = Output Distance = Resistance Distance = Input Force Resistance Force = Input Distance = Effort Distance = Output Force

8. Other forms of the MA formula:

9. Mechanical Efficiency Mechanical Efficiency = Work Output X 100 Work Input

10. Inclined Plane Reduces force, but increases distance The mechanical advantage of an inclined plane is length divided by height. Wedges and screws are types of inclined planes.

12. MA = L/H

13. Wedge A wedge generates outward forces A wedge is a type of inclined plane. Its mechanical advantage is its length divided by its greatest thickness.

14. Screw A screw is an inclined plane wrapped around a cylinder Uses a small force over a longer distance The closer the threads, the lower the force required

15. Levers – Three Classes Can change direction & size of force In a first-class lever, the fulcrum is between the force and the load. In a second-class lever, the load is between the force and the fulcrum. In a third-class lever, the force is between the fulcrum and the load.

16. First Class Lever Change direction & maybe force

17. Second Class Lever Change force, but not direction

18. Third Class Lever Don’t change direction, output < input

19. Pulleys Change direction and may change input force Types of pulleys include fixed pulleys, movable pulleys, and block and tackles.

21. Wheel and Axle The mechanical advantage of a wheel and axle is the radius of the wheel divided by the radius of the axle.

22. Compound Machines Compound machines consist of two or more simple machines. Compound machines have low mechanical efficiencies because they have more moving parts and therefore more friction to overcome.