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Newton’s Second Law: Rear End Collisions. Active Physics 3.4. November 29, 2010 Homework: 3.4 PTG, p 299 #1-7 due Tuesday. Learning Objective Apply Newton’s 1 st and 2 nd Law to automobile crashes Process Skill: Rewrite/Follow step-by-step procedures Success Criteria

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Active Physics 3.4

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Newton’s Second Law: Rear End Collisions

## Active Physics 3.4

### November 29, 2010Homework: 3.4 PTG, p 299 #1-7 due Tuesday

• Learning Objective

• Apply Newton’s 1st and 2nd Law to automobile crashes

• Process Skill: Rewrite/Follow step-by-step procedures

• Success Criteria

• Describe the causes of whiplash

• Provide examples of Newton’s 1st and 2nd 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

Rewrite procedures in your own words.

Be sure to leave spaces to record data and observations

OK with Law before going into lab

Materials Needed

Ramp

2 Crash carts

Manila Folder

Ring stand

Clay passengers

Seat papers

Scissors

Meter Stick

Masses

### Exit Ticket

• What type of seat causes less whiplash? Explain why in terms of Newton’s 1st and 2nd Law.

### November 30, 2010HW: None

• Learning Objective

• Apply Newton’s 1st and 2nd Law to automobile crashes

• Process Skill: Rewrite/Follow step-by-step procedures

• Success Criteria

• Describe the causes of whiplash

• Provide examples of Newton’s 1st and 2nd 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

• Honors Presentations

• Libby

### Physics Talk 3.4

• What is Newton’s 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, of change in direction.

• F=ma

### Rear-End Collision

• 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!

Actout

### Newton’s Second Law

• Important note about Newton’s second law

• All accelerations are caused by unbalanced, outside forces

• It does not say that all forces cause acceleration, only unbalanced ones.

• How does Newton’s 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

• How does Newton’s 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

Pg. 298

Answer all questions in complete sentences

### Essential Questions:

How does Newton’s Second Law apply to rear-end collisions and whiplash?