Natural Laws and Car Control

1
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 last100 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 owners 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. _at_
  60 MPH Total stopping distance is the length of a
  football field

15
Stopping Distance

• If a vehicles 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