1. Levers in the Body PH 532 EQ: How does your body work as a machine?

4. 1. What is a force? A push or pull on an object.

5. Force is represented by arrows The units of force are: Newton (N)

6. 2. What is work? When a force makes an object move

7. Why does it take more work to lift a heavier plant? Because a greater force is required!

8. 3. What is a machine? Devices that help you do work

9. 4. What is a lever? A rigid object that rotates about a fixed point (fulcrum) A)A simple machine…helps you do work! Fulcrum: a fixed point …where a lever rotates

10. Diagram:

12. 5. How does a lever make work easier? 1.Changing the amount of force, 2.Changing the distance, 3.Changing the direction.

13. Why does the girl place the fulcrum close to the crate? To increase the force as much as possible!

14. 6. What is mechanical advantage? A measure of how much easier it is to do work by using a machine

16. 7. How do you find the mechanical advantage of a lever? Mechanical advantage = resistance force effort force 100 N 25 N

17. Or: Length of Effort Arm Length of Resistance Arm

18. 8. What are the 3 kinds of levers? 1. First Class 2. Second Class 3. Third Class

19. 9. Draw a first class lever. 1 st class Example: see-saw, scissors, crowbar Body: neck!

23. 2 nd class Examples: wheelbarrow Body: foot!

27. 3 rd class Example: broom, rake, catapult Body: arm

31. How many different classes of levers are there? Three!

32. 9. How do levers function on the body? Bones and muscles work as lever systems joint = fulcrum bone = lever muscles = provide force