Teacher Resources

1
Teacher Resources

• Chapter 4 Color Teaching Transparency
• Ch 4.1
• Laboratory Black line Masters
• Electronic Book
• Skill Sheets

2
Chapter 4.1Forces In Machines

• CPO Science
• Integrated Physics Chemistry

3
Developing A Model

• Name something that you think is a machine today.
• Is it possible to use several smaller machines
  that make up one larger machine?
• What do these machines have in common?

4
Key Questions

• What is a simple machine?
• How do simple machines work?
• Is a block tackle a machine?
• What is an input output force?
• How can you measure the input and output force?
• What does this tell us?

5
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
• Number of strings supporting weights

6
Run The Experiment

• Set up the pulley and the blocks
• Tips
• Make sure to use the marker to keep track of
  where you started
• Start with the yellow string clipped to the top
  block(pulley) record 2,4,6 supporting strands
  first
• Then clip the string to the bottom block(weight)
  for supporting strands 1,3,5

7
What Did You Learn?

• What are the relationships?
• What is the relationship between the number of
  support strings and the input force?
• Is this an inverse or direct relationship?
  Strong or weak?
• Is there any math rule we can use to describe
  this relationship?
• Did you notice anything about the distances you
  pull and the number of supporting strands?

8
Summary

• Is a block tackle a simple machine?
• How do you know?
• Can you determine the mechanical advantage of the
  block tackle?
• How? Is there a relationship between M.A. and
  the number of support strands?
• Why do you think the number of supporting strands
  times the input force equals the output force?