EVOC Emergency Vehicle Dynamics & Physics 2 — Questions and Answers
Question 1: During hard emergency braking, vehicle weight transfers to which end of the vehicle?
- The rear axle
- The front axle (Correct answer)
- Evenly across all four wheels
- The uphill side on banked roads
Correct answer: The front axle
Inertia causes the vehicle's mass to continue forward during braking, transferring weight onto the front axle and increasing front-tire traction.
Question 2: What is 'understeer' in vehicle dynamics?
- When rear wheels lose traction and the tail slides outward
- When front wheels lose traction and the vehicle plows straight despite steering input (Correct answer)
- When the vehicle rolls to one side during a sharp corner
- When braking force is greater at the rear than the front
Correct answer: When front wheels lose traction and the vehicle plows straight despite steering input
Understeer occurs when front tires lose grip, causing the vehicle to continue in a straight path regardless of the steering wheel input.
Question 3: What is 'oversteer' in vehicle dynamics?
- When the front wheels lose traction and the vehicle understeers
- When the vehicle requires excessive steering input at low speeds
- When the rear of the vehicle slides outward during a turn (Correct answer)
- When the vehicle rolls toward the outside of a curve
Correct answer: When the rear of the vehicle slides outward during a turn
Oversteer occurs when rear tires lose traction, causing the rear end to swing outward and the vehicle to rotate beyond the intended turn.
Question 4: During rapid acceleration from a stop, vehicle weight transfers to which axle?
- Front axle
- Rear axle (Correct answer)
- Evenly to both axles simultaneously
- Whichever axle has the most traction
Correct answer: Rear axle
Inertia resists forward acceleration, causing weight to shift rearward and reducing traction at the front axle during hard acceleration.
Question 5: How does a higher center of gravity affect rollover risk in an emergency vehicle?
- Reduces rollover risk by lowering the vehicle's effective mass
- Has no effect unless the vehicle is on a banked surface
- Significantly increases rollover risk, especially during sharp turns (Correct answer)
- Only increases rollover risk when exceeding posted speed limits
Correct answer: Significantly increases rollover risk, especially during sharp turns
A higher center of gravity increases the lever arm of the tipping moment, making lateral forces more effective at rolling the vehicle.
Question 6: Why is understanding weight transfer important for emergency vehicle operators?
- To calculate maximum legal cargo weight for DOT compliance
- To predict handling changes and maintain control during acceleration, braking, and cornering (Correct answer)
- To determine the proper tire pressure for different load conditions
- To comply with weight distribution requirements on bridges
Correct answer: To predict handling changes and maintain control during acceleration, braking, and cornering
Understanding weight transfer allows operators to anticipate how the vehicle will respond and make proactive, precise control inputs.
Question 7: What is 'threshold braking'?
- Pumping brakes at one-second intervals to prevent lockup
- Applying maximum brake pressure just below the wheel lockup point (Correct answer)
- Gradually increasing brake pressure over a 5-second period
- Applying and releasing brakes alternately every half second
Correct answer: Applying maximum brake pressure just below the wheel lockup point
Threshold braking maximizes deceleration by applying pressure right at the edge of wheel lockup without triggering a skid.
EVOC Emergency Vehicle Dynamics & Physics 2
During hard emergency braking, vehicle weight transfers to which end of the vehicle?