Upload
jaden-horrocks
View
220
Download
1
Tags:
Embed Size (px)
Citation preview
Idaho Public Driver Education Idaho Public Driver Education
Natural Laws Affecting Vehicle
Control
GRAVITYGRAVITY
The natural force that pulls all things to earth
Throw a ball into the air and it________
Gravity gives objects their ________
The center of gravity is where a body’s mass is ___________
ENERGY OF MOTIONENERGY OF MOTION
The white truck and the dump truck are going the same speed.
Which vehicle has more energy of motion?
Why?
EFFECT OF SPEED AND WEIGHTEFFECT OF SPEED AND WEIGHTA vehicle’s energy of motion changes in
proportion to the square of the change in speed
Takes FOUR times the distance to stop
20mph
To 40mph20mph
To 60mph
Takes NINE times the distance to stop
EFFECT OF SPEED AND WEIGHTEFFECT OF SPEED AND WEIGHT
To stop a vehicle going 60mph would generate approximately enough heat to boil ½ gallon of water!
½ Gallon
INERTIAINERTIA
Inertia wants to keep these parked cars at rest.
• Inertia also wants to keep these moving cars moving.
Why, when driving through this curve, does inertia create the sensation that you are being pulled to the outside of the curve?
INERTIAINERTIA
Because you are traveling in a straight line and inertia wants to keep you going in a straight line
MOMENTUMMOMENTUM
• 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
MOMENTUMMOMENTUM
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!
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?
Pitch
PITCH, ROLL, YAWPITCH, ROLL, YAW
Yaw
Roll
FORCES OF IMPACTFORCES OF IMPACT
When two objects collide, 3 factors determine how much force there will be on impact
1. Speed
2. Weight
3. Duration
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
FRICTIONFRICTION
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
FRICTION: 4 TypesFRICTION: 4 Types
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
TIRES AND TRACTIONTIRES 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!
Consumers of Traction
Acceleration Force
Braking Force
Turning Force
Traction PiesTraction Pies
Large Steering and Braking Forces Exceed Traction Limits
Large Steering Force Large Braking Force
In a hard braking situation, most of the traction is needed for braking
Add hard steering will result in loss of control
FORCE EFFECT ON OCCUPANTSFORCE 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
MAINTAINING VEHICLE BALANCEMAINTAINING 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 motion occurs, weight transfer on the tires changes the size of the tire patches
As soon as the vehicle accelerates, brakes, or turns, the vehicle balance is changed
Going up or down a hill, or around a corner, or BOTH at the same time, really puts physics into play!
MAXIMUM VEHICLE LOADMAXIMUM VEHICLE LOAD
Load capacity includes the combined weight of people and Load capacity includes the combined weight of people and cargo that the vehicle is designed to safely handlecargo that the vehicle is designed to safely handle
THE ULTIMATE VEHICLE OVER LOADTHE ULTIMATE VEHICLE OVER LOAD
Maximizing Traction and ControlMaximizing 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!
THE THREE COLLISIONS in a THE THREE COLLISIONS in a
CRASHCRASH
Body into steering wheel, dashboard, other passengers, etc.
There’s no airbag inside the skull! If the person lives, the result can be severe brain damage.
Protecting your Passengers Should be Your First Protecting your Passengers Should be Your First Priority!Priority!
– 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
–Proper adjustment to avoid neck injury
–Seat position
Idaho Child Safety Seat Laws
Head Restraints
Adjustable
Shoulder-Belt Mount
Head RestraintAir Bag
Crash Sensors
Gases Vent Opening
Occupant ProtectionOccupant Protection
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
Adjusting Belts for Proper FitAdjusting Belts for Proper Fit
AIR BAGSAIR BAGS
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
Air Bags in Dash or Steering Wheel
Like Most Victims, Julie Knew Her Killer…
In the front AND back!