Natural Laws and Car Control Chapter 10 Natural Laws and Car Control

Man Made Laws Police enforcement Judge Jury

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

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

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

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

Friction Resistance to motion between any two objects that touch

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

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

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

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

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)

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

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

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?

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

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