• Levers in the BodyPH 532

EQ: How does your body work as a machine?

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

• Force is represented by

arrows

• The units of force are:

Newton (N)

2. What is work?

• When a force makes an object move

• Why does it take more work to lift a heavier plant?

Because a greater force is required!

3. What is a machine?

• Devices that help you do work

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

Diagram:

5. How does a lever make work easier?

1. Changing the amount of force,

2. Changing the distance,

3. Changing the direction.

• Why does the girl place the fulcrum close to the crate?

To increase the force as much as possible!

6. What is mechanical advantage?

• A measure of how much easier it is to do work by using a machine

7. How do you find the mechanical advantage of a lever?

Mechanical advantage = resistance force

effort force

100 N25 N

• Or:

Length of Effort Arm

Length of Resistance Arm

8. What are the 3 kinds of levers?

• 1. First Class

• 2. Second Class

• 3. Third Class

9. Draw a first class lever.

1st class

Example: see-saw, scissors, crowbar

Body: neck!

2nd class

Examples: wheelbarrow

Body: foot!

3rd class

Example: broom, rake, catapult

Body: arm

• How many different classes of levers are there?

Three!

9. How do levers function on the body?• Bones and muscles work as lever systems

joint = fulcrum

bone = lever

muscles = provide force