1. Newtons Second Law: Rear End Collisions

2. Learning Objective Apply Newtons 1 st and 2 nd Law to automobile crashes Process Skill: Rewrite/Follow step-by-step procedures Success Criteria Describe the causes of whiplash Provide examples of Newtons 1 st and 2 nd Laws in automobile crashes Analyze safety devices in preventing whiplash Do Now Copy LO and SC on new left side page! WDYS/WDYT p 292 Agenda Do Now: Lab with more clay crash dummies! Summary

3. Rewrite procedures in your own words. Be sure to leave spaces to record data and observations OK with LePera before going into lab

4. Materials Needed Ramp 2 Crash carts Manila Folder Ring stand Clay passengers Seat papers Scissors Meter Stick Masses

5. What type of seat causes less whiplash? Explain why in terms of Newtons 1 st and 2 nd Law.

6. Learning Objective Apply Newtons 1 st and 2 nd Law to automobile crashes Process Skill: Rewrite/Follow step-by-step procedures Success Criteria Describe the causes of whiplash Provide examples of Newtons 1 st and 2 nd Laws in automobile crashes Analyze safety devices in preventing whiplash Do Now: Why is it important to align the headrest appropriately to the height of the driver? Agenda Do Now Physics Talk Summary

7. What is Newtons Second Law? If a body is acted on by an unbalanced force, it will accelerate in the direction of the unbalanced force. The acceleration will be larger for smaller masses. The acceleration can be an increase in speed, decrease in speed, or change in direction. F=ma

8. What is whiplash? Why does it hurt? A serious injury often caused by a rear-end collision. The back of the seat, pushes the torso forward, leaving the head behind. This strains the neck and damages the alignment in the spine. The neck then snaps forward. Ouch!

10. Act out

12. Important note about Newtons second law All accelerations are caused by unbalanced, outside forces It does not say that all forces cause acceleration, only unbalanced ones.

13. How does Newtons Second law apply to holding a book? The force of your hand and the force of gravity are opposite forces acting on the same object, so the forces cancel out = no net force

14. How does Newtons Second Law apply to a car traveling at a constant speed? Since there is no acceleration, there is no net force. This means the forces are balanced. The forces of the engine on the tires and road moving the car forward must be equal and opposite of the air pushing back on the car

16. Pg. 298 What does it mean? How do you know? Why should you care?

17. How does Newtons Second Law apply to rear- end collisions and whiplash?