OttawaTownshipHigh School

Drivers Education

Chapter 5 – Natural Laws and Car Control

5.1 - Gravity and Energy of Motion

Gravity and energy of motion are natural laws that will affect the way your vehicle performs.

Gravity – is the force that pulls all things to Earth.

Lose speed when going uphill unless you use extra power

Increase your speed when going downhill unless you control it

Your braking distance will be longer when going downhill

Center of Gravity – Illustration on pg 92 – Point around which an objects weight is evenly distributed.

Energy of Motion – when an object moves it acquires energy

The faster your vehicle moves, the more energy of motion it has

Affected by the weight of the object **illustration pg 93

Truck’s energy of motion doubles when its weight is doubled by a load

Two times the weight means double the stopping distance

When trucks speed doubles, it need 4 times the distance to stop

Remember Normal following distance is 2 second rule, but with added weight it is the 4 second rule

5.2 - Friction and Traction

Friction – Force that keeps each tire from sliding on the road

Traction – friction created by the tire on the road

Tread – grooved surface of a tire that grips the road – bald tires are dangerous it will not grip wet or icy roads. With no tread the tire may puncture causing a blowout – all the air escaping at once

Hydroplaning– skidding over water on the road

  • Prevention of Hydroplaning
  • Slow down
  • Have proper inflation in tires
  • Proper tread
  • Avoid deep water

Underinflation & Overinflation see illustration pg 95

Why you should keep your tires Properly Inflated?

  1. Good gas mileage
  2. No flats
  3. Less hydroplaning
  4. Tire ware
  5. Better stopping
  6. Better handling
  7. Better traction

Wear of tires, shock absorbers, or steering system – traction and control will be reduced

** make sure there is at least one-sixteenth of an inch of tire tread! See Illustration pg. 96

Road Surface – straight, dry, and flat roads are the best for control

Checking Traction:

  1. Check your rear zone to make sure no traffic is near.
  2. Brake gently to see how your vehicle responds
  3. If your vehicle does not slow or if your antilock brakes start to work, reduce speed even further

Vehicle Control in Curves:

Speed – can’t control sharpness but you can control speed

Sharpness of Curves –the sharper the curve the more traction you need

Banked Curves (higher on outside than on inside) – helps with the tendency of moving to the outside of your lane

Load

5.3 – Stopping Distance

Total Stopping Distance – the distance your car travels while you make a stop

Perception Time – time it takes to IPD

Reaction Time – the time it takes you to (E) execute your decision

Braking Distance – the distance your vehicle travels from the time you apply the brake to the time you actually stop

****Perception Time + Reaction Time + Braking Distance = Total Stopping Distance****

Factors that affect Braking Distance:

  1. Speed
  2. Vehicle Condition
  3. Roadway Surface
  4. Driver Ability
  5. Antilock Braking System
  6. Hills
  7. Loads

5.4 – Controlling Force of Impact

Force of Impact – the force with which a moving object hits another object – 3 factors determine how hard something will hit another object

  1. Speed – most important – determines how hard something is hit
  2. Weight –heavier the vehicle more damage it will cause
  3. Distance between impact and stopping– barrels of sand around a post

How to wear safety belts:

  1. Adjust your seat
  2. Low and hung across hips
  3. Shoulder belt should be snug

Seatbelts are considered active restraint devices as you must manually put it on

**Air Bags provide front, side and rollover protection, but only work once**

Air Bags

Deploy at speeds over 200 mph

Airbags are considered passive restraint devices as they work automatically

Designed to work with safety belts this is why they are called supplemental restraint

Drivers chest should be at least 10 inches away from the steering wheel

Front seat passenger your seat should be as far back as possible

Tilt steering wheel so that it will deploy towards your chest

3 Collisions:

  1. Car hits something(ex. Tree)
  2. Person inside car hits something(ex. Dashboard or Seatbelt)
  3. Internal organs collide(ex. Spleen/Intestines punctured by spine)

Children:

Children in child seats and young people up to the age of 12 must sit in the back seat

Kids under 8 years of age should be in car safety seats

  1. Children under 1year of age should be rear facing (p.103)
  2. Children 1-3 years (up to 30lbs.) should be in a child safety seat with a 5-point harness
  3. Children 3-8 years(up to 80lbs) should be in a booster seat

Other Protection Devices:

  1. Automatic safety belts
  2. Front and rear crush areas
  3. Energy-absorbing bumpers
  4. Side door beams
  5. Reinforced windshield
  6. Energy-absorbing steering wheel and column
  7. Padded dash
  8. Child Seats
  9. Head Restraints