1. Natural Laws and Car Control
Chapter 10
Natural Laws and Car Control

2. Man Made Laws
Police enforcement
Judge
Jury

3. Natural Laws Controls our universe
Understand that are going to effect vehicle handling characteristics
Breaking a natural law might have dire consequences

4. Gravity
Force that tends to pull all objects to the center of the earth
Effects acceleration and braking

5. Center of Gravity
Point around which all the weight in a vehicle is centered or balanced
Major concern with SUV is the tendency to flip in a collision

6. Inertia
A body in at rest stays at rest, a body in motion stays in motion in a straight line until acted upon by an outside force
This is why we need to slow down before we get into a curve and speed up half way in the curve

7. Friction
Resistance to motion between any two objects that touch

8. Coefficient of Friction
Measurement of friction
Dry asphalt is .78
Wet asphalt is .60
Dirt road is .20
Dry snow is .20
Wet snow is .10
It takes 4 times longer to stop on dirt road as dry asphalt

9. Traction Acceleration traction Braking traction Cornering traction
All three overcome inertia (rest, motion, straight line)

10. Affects Traction Tires (type, wear, inflation)
Road surface (asphalt, concrete, gravel, dirt)
Condition of road surface (rain, snow, ice)
Weight of vehicle
Type of vehicle
Bank of road/curve
Speed of vehicle
Driver response
Temperature of road/tires

11. Tire Inflation Critical Handling of the vehicle Life of the tires
Gas mileage

12. Tire Ratings
Mileage rating (how long the tire last;100 rating should last 30,000 miles, 200 rating 60,000 miles)
Temperature rating (A is best, B not as good, C should not be used in hot weather or severe road conditions)
Friction rating ( wet road braking rating; A is highest, C is lowest)

13. Air Pressure of Tires
Air pressure can be found stamped on the tires and listed in owner’s manual

14. Stopping Distance Perception time/distance PT/D
Reaction time/distance RT/D
Braking distance BD
Review: the time you identify, predict and decide to stop is PT/D; RT/D is moving you foot from gas to brake; BD is time your car brakes to stop. @ 60 MPH Total stopping distance is the length of a football field

15. Stopping Distance
If a vehicle’s speed doubles, it needs 4 times stopping distance. To figure this, you take 2 square or 4
Question: a vehicle triples its speed, how much distance does it need to stop?

16. Kinetic Energy of Motion
Potential energy stored within a moving object
Determined by the speed and weight of an object

17. Force of Impact Kinetic energy divided by stopping distance
The longer the distance, the less severe the force of impact