Chapter 9- Natural Laws and Car Control Flashcards
active restraint device
a device you must engage, such as a safety belt
blowout
when all the air escapes the tire at once
braking distance
the distance your vehicle travels from the time you apply the brake until you stop
center of gravity
the point around which an object’s weight is evenly distributed
energy of motion
kinetic energy
force of impact
the force with which a moving object hits another object
friction
the force that acts between materials as they move past each other
gravity
the force that pulls all things to Earth
inertia
objects at rest tend to stay at rest and objects in motion tend to stay in motion unless acted on by an unbalanced force
momentum
the inertia of an object in motion
passive restraint device
a device that works automatically, such as an airbag
perception distance
the distance your vehicle travels during your perception time
perception time
the length of time it takes you to identify a hazard, predict a conflict, and decide to brake
pitch
a tilting motion from front to back
reaction distance
the distance your vehicle travels while you react
reaction time
once you identify a hazard, the length of time it takes you to apply the brake
total stopping distance
the distance your car travels from the time you first perceive a hazard until you stop
traction
a form of friction; happens when tires roll over the surface of the road
tread
the grooved surface of the tire
vehicle balance
distribution of a vehicle’s weight on its tires as they contact the ground
What is a vehicle’s energy of motion proportional to?
it’s weight and the square of its speed
What does gravity affect?
driving up and down hills
What must tires be to provide the most traction?
have good tread and be inflated properly
What is a vehicle’s center of gravity affected by?
weight and load
What is control in curves affected by?
speed, the sharpness of the curve, the shape of the roadway, and vehicle load
What does total stopping distance include?
perception distance, reaction distance, and braking distance
What is braking distance affected by?
the driver’s ability to see and react, vehicle speed, condition of the vehicle and road surface, momentum, and vehicle load
What is the force of impact determined by?
vehicle’s speed and weight, and the time between impact and stopping
What does the proper use of restraint devices do?
protect against injury in collisions
What does the amount of momentum depend on?
the object’s weight and speed
A vehicle’s energy of motion changes in proportion to the…
weight of the vehicle, and the square of its speed
Traction is used to…
control speed, steer, and brake
Footprint
the place where a tire tread touches the road
What do the grooves in the tread do when it’s raining?
water flows through the grooves in the tread and away from the tire, allowing the tire to grip the road
What does tire size affect? What should you do?
affects tread and traction on the road; should check the owners manual for max tire size
What will an uninflated tire do?
only grip with the outer edges, wear out quickly, accept less stress, and is more likely to heat up and fail
What will an overinflated tire do?
only grip with the center of the tread and will wear out faster
What will changing temperatures do for tire pressure?
cold weather decreases, hot weather increases
What should you do for your tires regularly? When?
check the tire pressure but only before you’ve driven
What will happen if the steering and braking requirements of traction exceed the amount available?
the vehicle will skid and you may lose control
What does all-wheel drive mean?
all wheels have pulling power
What are the three things that are required to have good traction?
1) vehicle has to be in good condition, 2) road surface must be smooth and clear, 3) your actions must maximize traction
Traction and control will be reduced if you allow what to wear?
tires, shock absorbers, or parts of the steering system
What are dangerous and could suffer a blowout?
bald tires
What will worn shock absorbers do?
cause tires to bounce on a rough road
When will traction be reduced?
when you drive on a gravel road or a road with snow or rain
What will freeze first?
bridges and shaded areas
What do you do when you see the road condition about to change?
slow down, test it, and if need be slow down even more
How can you maximize traction?
steer, accelerate, and brake gently and smoothly
When is the only time a vehicle is in complete balance?
when it is not moving
When you balance something on your finger, where is your finger?
directly under the center of gravity
Where is the center of gravity in a car?
more toward the front and wheels
What type of cars tend to have a higher center of gravity?
SUVs, pickups, and vans
What can raise the center of gravity?
carrying heavy cargo and installing large tires
What do you do if you lose traction in your front tires from applying the brake?
don’t accelerate or apply brakes, just look and steer toward your target
Yaw
turn clockwise or counterclockwise
When may your vehicle yaw?
when your rear vehicles lose traction
What are the 3 common roadway shapes?
level, crowned, and banked
Crowned surface pro and con
rain drains quick and easy, but you don’t get as much traction on a curve
What kind of roadway will help you overcome inertia on a turn?
banked with the outside raised, because gravity pulls you into the curve
What should you do when stopping quickly?
1) perceive, 2) react, and 3) brake to a safe stop
You should always be able to stop within…
the distance you can see ahead
What is the average perception time for alert drivers?
3/4 of a second
Perception time varies based on…
visibility, alertness, and your line of sight
What factors affect braking distance?
driver ability, speed, vehicle condition, roadway surfact, hills, and vehicle weight
What determines force of impact?
speed, weight, and time between initial impact and stopping distance
Which has the higher force of impact- if you hit a wall of if you hit a bush
wall because you’re going to be stopped completely then and there
What do safety belts do?
distribute the force of impact to the strong areas of your body- the pelvis, shoulders, and chest
Advanced airbags
airbags that deploy with the appropriate amount of speed based on sensors that collect information
How far away from the hub of the steering wheel should you be?
10 inches
Crush zone
the front and back of the vehicle that are designed to absorb impact
What are bumpers designed for?
less than 5 mph of impact without damage
Side impact panels
help absorb crash energy and reduce objects penetrating the passenger compartment
