Teacher Resources

1
Teacher Resources

• Chapter 4 Color Teaching Transparency
• Ch 4.2
• Laboratory Black line Masters
• Electronic Book
• Skill Sheets

2
Chapter 4.2The Lever

• CPO Science
• Integrated Physics Chemistry

3
Developing A Model

• Can you give me an example of a lever?
• What is the input force and the output force?
• What makes a lever?

4
Three Classes of Levers

• First Class - fulcrum between Input and output

• Second Class output between fulcrum and input

• Third Class input between fulcrum and output

5
Key Questions

• What is a lever?
• How does a lever work?
• Does a lever fit our definition of a machine from
  Ch. 4.1?
• How can we calculate the mechanical advantage of
  a lever?

6
Developing An Experiment

• What variables are there?
• What are we going to test?
• What material will we need?
• What data needs to be collected?
• Input output force
• Length of the arms

7
Run The Experiment

• Set up the lever
• Tips
• Before you start recording data try and get
  several different combinations to balance
• Once you have your data develop a mathematical
  rule for the lever

8
What Did You Learn?

• What are the relationships?
• What did you notice about the lengths of the
  input output arms of the lever and the weights?
• If I need to lift a large object with a lever, do
  I want to be close to the fulcrum or far from it?
  
• Is there any math rule we can use to describe
  this relationship?
• For a lever is there more than one way to find
  mechanical advantage?

9
Summary

• Is a lever a simple machine?
• How do you know?
• Can you determine the mechanical advantage of the
  lever?
• How? Is there more then one way to calculate it?