1. UNIT 5 CHALLENGES TO VEHICLE CONTROL
Chapter 12
Vehicle Movement

2. LESSON 1 USING APPROPRIATE SPEED
Factors which adjust how fast you should be going:
Reduced visibility (night, fog, rain, snow)
Poor traction (rain, snow, ice)
Improper space
Adjust speed:
When passing
Maintaining a safe following distance
In bad weather

3. LESSON 2 TOTAL STOPPING DISTANCE
Total Stopping Distance – the distance it takes to stop a vehicle
Doubling your speed multiplies your braking distance by four times (30 mph = 37.5 feet, 60 mph = 150 feet)
Human-perception distance – distance you travel from the time your eyes see a hazard until your brain recognizes it:
1/2 to ¾ second
Adds from 15 to 66 feet to total stopping distance

4. Total stopping distance:
Human-reaction distance – the distance traveled from the time your brain tells your foot to move from the accelerator until the time your foot pushes the brake pedal
½ to ¾ second
Adds from 44 to 66 feet to distance travelled at 60 mph
Vehicle-braking distance – the distance it takes the vehicle to stop once you apply the brakes
0 to ¼ second
A car going 60 mph can take as much as 3 ½ to
4 ¼ seconds and an additional 160 feet to stop

5. Braking capability depends on the following factors:
Type of braking system
Brake pad material
Brake alignment
Vehicle’s tire pressure
Tire tread and grip
Vehicle weight
Suspension system
Friction of road surface
Wind speed
Slope of road
Road surface smoothness
Braking technique applied by the driver

6. LESSON 3 NATURAL LAWS AND THE MOVEMENT OF YOUR VEHICLE
Inertia - moving objects continue to move in a straight line unless some force acts on them and objects at rest do not move unless some force acts on them
Braking hard causes you to keep moving forward
Because of this, wearing a seatbelt can keep you and others from being thrown from the car in a frontal crash

7. Friction - the force between two surfaces that resists the movement of one surface across the other (holds two surfaces together)
Allows your tires to “stick” to the surface of the road
Traction – (adhesion – “sticking together”) holds your vehicle on the road. Traction is affected by:
Tire pressure
Tire condition
Rain
Ice and snow
Road condition
Vehicle’s suspension

8. Kinetic energy - energy of motion.
Momentum - quality of motion in a moving object. The greater the momentum of a vehicle, the greater the damage in a collision will be.
Weight
Speed
Kinetic energy - energy of motion.
The more kinetic energy a vehicle has, the more time and distance it will take to stop.
The more kinetic energy a vehicle has, the greater the force of impact when in a collision

9. Gravity - a force that pulls all objects toward the center of the earth
Causes objects to speed up (vehicle going down hill)
Causes objects to slow down (vehicle going up hill)
Center of gravity – the point where the weight of an object is evenly distributed (in a car it is the center of the vehicle)
Small cars sit low to the ground and are therefore more stable than SUV’s and vans
SUV’s, vans and trucks need to slow down considerably when going around a curve to avoid rolling over
Loading the roof of a vehicle will raise it’s center of gravity

10. LESSON 4 NATURAL LAWS AND STEERING AND BRAKING
Factors which affect braking distance:
Speed
Vehicle condition (tires, brakes)
Roadway conditions

11. Factors and natural laws that affect steering:
Directional control – a vehicle’s ability to hold a straight line or to continue in a particular direction
Centrifugal force – pushes you in the direction opposite to the way you are turning
Tends to throw a spinning or turning object away from the center of the spin
If going around a curve to fast, the vehicle and people in the vehicle may continue to go straight
Can cause a vehicle to slide off the road
Can cause a vehicle to roll over

12. Banked curves – curves that are built higher on the outside of curves than on the inside. It works with the force of gravity to help you stay on the road through a turn.
Improves steering control
Helps to prevent a rollover
Crowned roads – roads that are higher in the center than at either of the edges
Facilitate drainage so water can run off the road when it rains
Causes vehicle to pull right
Steer slightly toward the center
Slow down to gain more control of the vehicle