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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.
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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