1. Idaho Public Driver Education Natural Laws Affecting Vehicle Control

2. The natural force that pulls all things to earth
GRAVITY
The natural force that pulls all things to earth
The center of gravity is where a body’s mass is ___________
Throw a ball into the air and it________
Gravity gives objects their ________

3. ENERGY OF MOTION
The white truck and the dump truck are going the same speed.
Which vehicle has more energy of motion?
Why?

4. EFFECT OF SPEED AND WEIGHT
A vehicle’s energy of motion changes in proportion to the square of the change in speed
To 40mph
20mph
Takes FOUR times the distance to stop
To 60mph
20mph
Takes NINE times the distance to stop

5. EFFECT OF SPEED AND WEIGHT
To stop a vehicle going 60mph would generate approximately enough heat to boil ½ gallon of water!
½ Gallon

6. INERTIA Inertia wants to keep these parked cars at rest.
Inertia also wants to keep these moving cars moving.

7. INERTIA
Why, when driving through this curve, does inertia create the sensation that you are being pulled to the outside of the curve?
Because you are traveling in a straight line and inertia wants to keep you going in a straight line

8. MOMENTUM Momentum is inertia in motion
Momentum is the product of speed and weight
A small truck filled with potatoes traveling at 20mph has more momentum that a 3,000 lb car traveling at the same speed
As momentum increases so does the potential for lots of damage in a collision

9. MOMENTUM
A 50 lb passenger traveling in a vehicle going 30mph will have momentum.
No matter how strong that passenger may be, he will not be strong enough to stop the body’s momentum when the vehicle comes to an abrupt stop during a crash!

10. U think U can bench press an elephant?
Some say, “I can brace myself in a wreck”, or “I’m strong enough to hold onto the steering wheel”.
U think U can bench press an elephant?

12. PITCH, ROLL, YAW
Yaw
Pitch
Roll

13. FORCES OF IMPACT 1. Speed 2. Weight 3. Duration
When two objects collide, 3 factors determine how much force there will be on impact
1. Speed
When a collision stops a vehicle in a very short time the impact will be greater than if it took a longer time to stop
2. Weight
3. Duration

14. FRICTION The amount of friction between the surfaces depends on:
Friction is the force when two surfaces move against each other and one surface resists the other
The amount of friction between the surfaces depends on:
What the surface is made of
What is on the surface
How rough or smooth it is
How much force is pushing the two surfaces together

15. FRICTION: 4 Types Friction creates TRACTION
1. Static: The holding force between 2 surfaces
2. Sliding: Friction that slows down a sliding object
3. Rolling: Friction between the ground and tire/wheel
4. Internal: Friction that occurs from resistance to motion within elastic objects
Friction creates TRACTION

16. TIRES AND TRACTION
Only four small areas underneath each tire holds the vehicle on the road!
When the car is not moving, it’s got GREAT (static) traction!

18. Traction Pies
In a hard braking situation, most of the traction is needed for braking
Add hard steering will result in loss of control

19. FORCE EFFECT ON OCCUPANTS
As the car enters a turn, inertial wants to keep the vehicle and occupants going straight
The seat position and seat belts hold the passengers in place through the curve

20. MAINTAINING VEHICLE BALANCE
The design balance for a vehicle is only reached when the vehicle is not moving, or is moving in a straight line at a constant speed
As soon as the vehicle accelerates, brakes, or turns, the vehicle balance is changed
As soon as motion occurs, weight transfer on the tires changes the size of the tire patches
Going up or down a hill, or around a corner, or BOTH at the same time, really puts physics into play!

21. MAXIMUM VEHICLE LOAD
Load capacity includes the combined weight of people and cargo that the vehicle is designed to safely handle

22. THE ULTIMATE VEHICLE OVER LOAD

23. Maximizing Traction and Control
Properly inflated tires not only increase traction, they improve gas mileage and save you money!
Tires with plenty of tread help maintain traction!
A good suspension system helps keep the tires on the road, maximizing traction!

24. THE THREE COLLISIONS in a
CRASH
1. Car hits object

25. 2. Head hits windshield
Body into steering wheel, dashboard, other passengers, etc.

26. 3. Brain hits skull
There’s no airbag inside the skull! If the person lives, the result can be severe brain damage.

27. Protecting your Passengers Should be Your First Priority!
Idaho Child Safety Seat Laws
Rear-facing infant seat – First year of life
Forward-facing infant seat – up to 40 lbs.
40 lbs. to age 7 - booster seat.
Age 7 – seat belt
Head Restraints
Proper adjustment to avoid neck injury
Seat position

28. Occupant Protection Adjustable Head Restraint Shoulder-Belt Mount
Air Bag
Gases Vent Opening
Crash Sensors

29. Adjusting Belts for Proper Fit
Lap belt
low across hips
snug across hips
avoids internal injuries
Shoulder belt
over collar bone and chest
avoids shoulder dislocation
avoids rib cage damage

30. AIR BAGS Air Bags in Dash or Steering Wheel
No passenger under 12 years of age in front seat
Protects against head and chest injuries
Speed of inflation is critical
Driver should adjust seat for minimum 10 inch clearance between chest and steering wheel
Hand position on wheel should be 9 and 3 or lower.
Aim steering wheel at chest not face

31. Like Most Victims, Julie Knew Her Killer…
Wear Your Seatbelt!
In the front AND back!