Drive Right Chapter 5 Natural Laws and Car Control Unit 3

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Drive RightChapter 5Natural Laws and Car
ControlUnit 3

• Theory Notes from
• MR. MILLERS
• Driver Education
• Class

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5.1 Gravity and Energy of Motion

• Gravity and energy of motion are both natural
  laws that will effect the way your vehicle
  performs.
• When you operate a small vehicle, like a bicycle,
  it is easy to control it because of the low speed
  and weight.
• A car or SUV can weigh as much as two tons (4,000
  lbs)!!
• Natural Laws can create forces that work against
  you in emergency situations.

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5.1 Gravity and Energy of Motion

• Gravity is the force that pulls all things to the
  earth.
• Gravity pulls your car towards the earth when you
  are driving.

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5.1 Gravity and Energy of Motion

• You can feel the pull of gravity as you drive up
  and down hills.
• When you drive uphill, you will lose speed unless
  you use extra power (gas pedal).
• If you want to maintain the same speed, you must
  increase the power to overcome the force of
  gravity.

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5.1 Gravity and Energy of Motion

• Gravity will increase your speed on a downhill
  road unless you control it.
• It will take you longer to stop, so you will need
  to brake earlier and downshift.
• Downshifting allows the engine not the brakes
  slow the vehicle down.

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5.1 Gravity and Energy of Motion

• How does uphill or downhill situations affect
  your intended path of travel?? 3 Ways
• Uphill your braking distance will actually
  decrease.
• Downhill your braking distance will be longer.
• The steeper the incline, the longer your or
  shorter your stopping distance.

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5.1 Gravity and Energy of Motion

• What is the definition of Center of Gravity
• The point around which an objects weight is
  evenly distributed is called it center of
  gravity.
• Example Circus high wire performers use poles
  to maintain their center of gravity.

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5.1 Gravity and Energy of Motion

• More examples of Center of Gravity
• Engineers try to make a vehicles center of
  gravity low so it can perform better.
• The higher the center of gravity the more
  unstable it becomes on steep hills and sharp
  turns.
• http//www.youtube.com/watch?vIO9zHIlcPp0

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5.1 Gravity and Energy of Motion

• Energy of Motion
• When objects move, it acquires energy. This
  force is called Energy of Motion or Kinetic
  Energy.
• The faster your vehicle moves, the more energy of
  motion it has.
• Energy of motion is also affected by the weight
  of the moving object.
• http//video.google.com/videoplay?docid-497866528
  0372660831

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5.1 Gravity and Energy of Motion

• Energy of Motion
• When the weight and speed of a vehicle increases,
  the stopping distance increases.
• If the weight doubles the stopping distance
  doubles.
• The stopping distance will change in proportion
  to the square of its change in speed. When the
  vehicles speed doubles the stopping distance is
  about four times as long.

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5.1 Gravity and Energy of Motion

• Energy of Motion
• Speed Kills!!
• We all understand the dangers of speeding.
• You will develop an ability to adjust to traffic
  situations ahead of time. You will see how
  important it is to slow before an emergency
  situation develops.
• Every time you cut your speed in half, you cut
  your energy of motion by four times!
• http//video.google.com/videoplay?docid-682411936
  0217412702qspeedingcarcrashtotal268start0
  num10so0typesearchplindex2

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5.1 Gravity and Energy of Motion

• Energy of Motion
• As you gain experience with driving, you will
  feel the laws of gravity and energy of motion
  affecting your car.
• Remember these laws when you need to judge how
  long it will take you to stop your vehicle.
• http//video.google.com/videoplay?docid-921074045
  8531367211qcrashtestdummiestotal791start0
  num10so0typesearchplindex2

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5.2 Friction and Traction

• Your four tires are the most important factor in
  controlling your car.
• In reality, your car makes tracks similar to an
  animal walking in the mud or snow.
• Each footprint is approximately twice the size of
  your hand.

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5.2 Friction and Traction

• Friction
• Is the force that keeps each tire from sliding on
  the road.
• You can feel this same force by rubbing your
  hands together.

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5.2 Friction and Traction

• Traction
• The friction created by the tire on the road is
  called traction.
• Traction makes it possible for your vehicle to
  grip the road so you can change speed and
  direction.

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5.2 Friction and Traction

• Tires
• Tires make a difference in the way your vehicle
  performs.
• Proper tire pressure can mean the difference in
  avoiding a crash and hitting something.

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5.2 Friction and Traction

• Tires
• The grooved surface of a tire that grips the road
  is called the tread.
• When the road is wet the tread allows water to
  flow through the grooves.
• This action allows the tire tread to cut through
  the water and grip the road.

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5.2 Friction and Traction

• Tires
• Warn or bald tires are dangerous.
• A bald tire will not grip a wet or icy road.
• Since it has no tread to push the flow of water
  away from the ground.
• It is also more vulnerable to a puncture or
  blowout.

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5.2 Friction and Traction

• Inflation
• Tires are designed to work best when they are
  properly inflated.
• Check the owners manual for best pressure to
  use.
• When your tire pressure is right, you will get
  the best control from your tires.

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5.2 Friction and Traction

• Inflation
• Under Inflation Only the outside edges of the
  tire provide traction.
• Split Traction You are dividing your traction
  between stopping, starting and turning.
• You have reduced traction based on the maneuver

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5.2 Friction and Traction

• Reduced Traction
• Ideal levels of traction can be maintained by
• Vehicle is in good mechanical condition.
• The road must be smooth, paved, level, and clean.

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5.2 Friction and Traction

• Vehicle Condition
• The older your vehicle the more important it is
  to properly maintain it.
• Good shocks are necessary to prevent your vehicle
  from bouncing.
• Worn tires limit your control.

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5.2 Friction and Traction

• Road Condition
• It is easy to drive on straight, dry, flat roads.
• Obviously snow or rain will effect that same
  roadway.
• Reduction in speed is the safest way to handle
  poor roadway conditions.
• Checking Traction When road conditions are bad,
  slow down your vehicle. You can use these steps
  to check how much traction you have
• Check your rear zone to make sure no traffic is
  near.
• Brake gently to see how your vehicle will
  respond.
• If your vehicle does not slow or if your antilock
  brakes start to work, reduce speed even further.

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5.2 Friction and Traction

• Curves
• Energy of motion and traction will work on your
  vehicle as you drive around a curve.
• The energy of motion in your vehicle will try to
  make it go straight in a curve.
• The higher your vehicles speed, the more it will
  tend to go straight.
• Vehicle Control in Curves
• Speed- slow down to reduce your chance of
  skidding.
• Sharpness in Curves- the sharper a curve, the
  more traction your vehicle needs to grip the
  road.
• Banked Curves- a curve that is higher on the
  outside than it is on the inside is called a
  banked curve. It helps in the prevention of your
  car moving to the outside of the curve.
• Load- your vehicles load affects your control in
  a curve.

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5.3 Stopping Distance

• Curves
• When you are driving and have to stop, three
  things must happen
• You must perceive the hazard in your path of
  travel
• React
• Brake your car to a stop
• The distance your car travels while you make a
  stop is called your Total Stopping Distance.

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5.3 Stopping Distance

• Total Stopping Distance
• Total Stopping Distance is the distance your car
  travels while you are attempting to stop it.
• The picture on Page 98 shows the distance it take
  once you see a hazard to the point where you stop
  your vehicle.

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5.3 Stopping Distance

• Perception Time and Distance
• The length of time you take to identify, predict,
  and decide to slow for a hazard is called your
  perception time.
• Perception time will vary greatly depending on
  visibility, the hazard, and your abilities at the
  time.
• The distance your vehicle travels during this
  time is your perception distance.
• Perception Distance is not easy to estimate.
• It will vary as driving situations change and
  become more complex.

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5.3 Stopping Distance

• Reaction Time and Distance
• Once you recognize a hazard, the length of time
  you take to execute your action is your reaction
  time.
• The average drivers reaction time is ¾ ths of a
  second.
• The distance your vehicle travels is called your
  reaction distance.

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5.3 Stopping Distance

• Braking Distance
• The distance your vehicle travels from the time
  you apply the brake until you stop is called
  braking distance.
• A vehicles energy of motion - and your braking
  distance are proportional to the square of the
  increase in speed.
• If you accelerate from 20 to 40 mph, your braking
  distance will be 4 times longer.

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5.3 Stopping Distance

• Estimating Stopping Distance
• The chart on page 99 shows your reaction distance
  and braking distance from different speeds.
• Use the four second rule, which enables you to
  project your approximate stopping distance under
  ideal conditions at any speed.

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5.3 Stopping Distance

• Estimating Stopping Distance
• Pick a fixed checkpoint ahead where you think you
  could stop.
• Count off four seconds one-thousand-one,
  one-thousand-two, etc.
• Check your vehicles position. If you have just
  reached your fixed checkpoint, you can assume the
  distance you estimated in step 1 was correct.

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5.3 Stopping Distance

• Factors that Affect Braking Distance
• Speed higher speed longer distance.
• Vehicle Condition worn tires or shocks longer
  distance to stop.
• Roadway Surface Rain, snow, ice, dirt, etc.
  reduce traction and increase distance.
• Driver Ability If you are distracted or
  impaired, your will take longer to stop.
• Antilock Braking System (ABS) You can better
  control your stopping distance in curves.
• Hills Your braking distance increase downhill.
• Loads Heavy loads increase your braking
  distance.

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5.4 Controlling Force of Impact

• Accidents happen in a blink of an eye. It is
  imperative that you do everything in your ability
  to protect yourself and your passengers.
• Forces of Impact
• In violent collisions, occupants need protection
  at all times. If they are not protected, they
  will be thrown against the vehicles interior in
  a second collision or ejected from the vehicle.
• The force with which a moving object hits another
  object is called Force of Impact.
• Three factors determine how hard something will
  hit another object
• Speed
• Weight
• Distance between impact and stopping

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5.4 Controlling Force of Impact

• Force of Impact
• Speed
• The most important factor in determining how hard
  a vehicle will hit another object.
• The force of impact is in proportion to the
  square of the increase or decrease in the
  vehicles speed.
• Any reduction in speed will greatly reduce the
  damage inflicted.
• Always try to reduce speed in an emergency.

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5.4 Controlling Force of Impact

• Force of Impact
• Weight
• The heavier a vehicle, the more damage it will
  cause in a collision.
• A vehicle weighing twice as much as another
  vehicle will hit a solid object twice as hard.
• http//video.google.com/videoplay?docid-457549925
  6983765631qtruckhittingwalltotal120start0
  num10so0typesearchplindex0

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5.4 Controlling Force of Impact

• Force of Impact
• Distance Between Impact and Stopping
• The distance a vehicle covers between the instant
  it hits an object and the moment it comes to a
  stop can vary greatly.
• Image hitting barrels filled with sand sitting in
  front of a light post rather than hitting the
  post itself.
• The barrels will slow you as you hit them rather
  than stopping you like the post would.
• This is why traffic engineers put cushioning
  materials in front of solid roadside objects.
• http//video.google.com/videoplay?docid3937168886
  833428491qcarhittingpoletotal124start0num
  10so0typesearchplindex8

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5.4 Controlling Force of Impact

• How to Wear Safety Belts
• Using safety belts is the 1 defense to reduce
  possible injury.
• They hold you in place and prevent you from being
  thrown from the vehicle.
• Follow these steps with your seatbelt
• Adjust your seat to an upright position.
• Make sure your seatbelt is not twisted.
• Snap the buckle into place and tighten the lap
  portion across your hips.
• Adjust the shoulder strap across your chest.
  Make sure it is snug.

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5.4 Controlling Force of Impact

• Air Bags
• Air bags will automatically inflate to protect
  you during a collision.
• It is a balloon type device.
• It takes approximately 25 thousandths of a
  second.
• They will deploy in speeds over 200 mph.
• http//video.google.com/videoplay?docid-564738734
  3618476179qairbagdeployingtotal59start10nu
  m10so0typesearchplindex3

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5.4 Controlling Force of Impact

• Air Bags
• Air bags are designed to work with seat belts.
• To prevent air bag injuries keep your hands at
  9-3 or 8-4.
• Sit away from an air bag after your are belted.
  Your chest should be 10 away from the steering
  wheel.
• If you have a tilt steering wheel, tilt it so
  your air bag will deploy toward your chest.
• Children in a child seat and young people under
  age 12 must sit in the back seats. They can be
  injured when an air bag deploys.

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5.4 Controlling Force of Impact

• Air Bag Improvements
• Engineers are now developing numerous features to
  make air bags even more effective.
• Advanced Air Bags because of previous injuries,
  some air bags can measure your seat position and
  weight of passengers.
• The air bag can deploy in two stages with
  appropriate speed and intensity.
• Some owners have air bag switches installed to
  give vehicle owners a choice about using an air
  bag.
• Check with your insurance policy to see if it is
  still valid and make sure your seat belts dont
  stretch.

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5.4 Controlling Force of Impact

• Other Protection Devices
• Engineers have designed additional devices in new
  vehicles to protect you
• Automatic Seat Belts
• Front and Rear Crash Areas
• Energy-Absorbing Bumpers
• Side Door Beams
• Reinforced Windshields
• Energy-Absorbing Steering Wheel Columns
• Padded Dash
• Child Seats
• Head Restraints