Unit 3: The Effect of Natural Forces on the Vehicle
How can you reduce the forces on you and your car during an unavoidable accident?
Head toward objects that will cause your car to stop over a greater distance, such as bushes rather than trees, snow, soft dirt, sand barrels, etc.
How do you prevent losing control in a turn and why?
In a turn, your car is subject to centrifugal force (which pulls your car away from the direction you want to turn and into a straight line). Traction is necessary to keep from losing control of your vehicle.
What causes skidding?
Skidding while braking is caused by the friction of your brakes being stronger than the friction force between your tires and the road, which causes you to lose traction
What is the purpose of barrels filled with sand in front of an abutment (such as a support for a highway overpass)?
To reduce the force of impact on your vehicle by allowing it to travel farther than if it hit the abutment directly
In a crash, the kinetic energy of your vehicle and body must be dissipated, the forces needed to dissipate this energy are lower if the time period over which your vehicle moves during the cash is longer, and if the car suddenly stops, the forces will be very high. (T/F)
True
The force of a vehicle increases as its momentum increases. (T/F)
True
When should you always engage your parking brake?
When parking on an incline
Describe the force of inertia.
While driving, inertia keeps your vehicle moving (unless acted upon another force). You may be injured because of the inertia and momentum of loose objects in your car that fly through the air during a sudden stop.
What is the best protection against injury if you have an accident?
Your seatbelt
Gravity _____ your kinetic energy when you are driving uphill and _______ it when you are driving downhill.
decreases, increases
What is the purpose of anti-lock brakes?
prevent your wheels from locking during a quick stop so that your brakes can continue to absorb energy and you can maintain traction
What is potential energy?
the energy that an object possesses because of its position or form
What is friction?
the force caused by the contact of one surface on another resulting in the resistance of an object moving over surface
If you increase your speed from 10 MPH to 20 MPH, what is the effect on your car's momentum? From 10 MPH to 50 MPH?
the momentum doubles, increases five times
Just in case your parking brake fails, you should always turn the front wheels of your vehicle so that it will not roll into the traffic lane. If you are facing downhill, you should always turn your front wheels towards the ____. If you are facing uphill and there is a curb, turn your wheels towards the _____ and if no curb towards the ______.
towards the curb/roadside, towards the middle, towards the side
How can loss of traction be avoided?
a) driving slower, b) properly using brakes
What is centrifugal force?
the tendency for objects to be pulled outward when rotating around a center
In order to keep a vehicle in a turn without allowing centrifugal force to pull the car out, what should you not do?
Accelerate while turning
Braking to a stop converts heat energy into kinetic energy in your brakes through friction. (T/F)
False; kinetic energy into heat energy
Give some examples of potential energy's relationship to your vehicle.
When you are parked on a hill, gravity gives your car potential energy; car suspension system
List the natural forces acting on the vehicle.
a) gravity, b) inertia, c) momentum, d) kinetic/potential energy, e) friction, f) centrifugal force
What is momentum?
the force of a moving object proportional to its weight and speed
If you increase your speed from 10 MPH to 20 MPH, you are dealing with how many times the amount of kinetic energy?
four
What is kinetic energy?
the energy something possesses because it is in motion
If you increase your speed from 10 MPH to 50 MPH, you are dealing with how many times the amount of kinetic energy?
twenty-five
How can you prevent whiplash?
use the headrest
How can you counteract inertia in your car?
wear a seatbelt
