Warmup:

1
Warm-up

• A bicycle traveling at 10 mph collides with a
  train traveling at 30 mph. Which force is
  greater the force that the bicycle exerts on the
  train, or the force that the train exerts on the
  bicycle?
• Why is there never a winner in a fist fight?

2
Quick Notes

• Newtons 3rd Law
• For every action force, there is an equal
  (magnitude) and opposite (direction) reaction
  force.
• ALL forces come in pairs (NO exceptions!)
• You cannot exert a force on something without
  that object exerting an equal force back against
  you!

3
Newtons 3rd Law

• Examples of force pairs
• Jumping off of the ground
• Action you push down on the ground
• Reaction the ground pushes you up!!
• Hitting a nail with a hammer
• Action hammer exerts force on the nail
• Reaction nail exerts force back on the hammer

4
Newtons 3rd Law

• Practice Problem identify at least 6
  action/reaction force pairs in this diagram

Ugly Truck Moving Co.
A
B
5
N3L Mini-Explorations

• For each of the three problems, do the following
  (on paper)
• Predict the answer (include reasons)
• Try it and report the actual answer
• Explain the actual answer (include force
  diagram(s) in your explanation)

6
Homework

• Finish the write-up for Newtons 3rd Law
  Mini-Explorations
• Return the lab sheets to me before leaving today
• Read pages 74 82 in the textbook if you havent
  already done so
• Finish Newtons 3rd Law Worksheet
• Print Newtons 3rd Law Force Diagrams for class
  next time