Practice Test Geeks(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test
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Vehicle Dynamics Flashcards

7 cards from real ACTAR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Vehicle Dynamics flashcards as text

  1. What is the 'slip angle' of a tire in vehicle dynamics?

    Answer: The angle between the tire's heading direction and its actual direction of travel

    Slip angle is the angle between the direction a tire is pointing and the direction it is actually traveling, which generates lateral cornering force.

  2. During a weight transfer event (braking), how does the normal force distribution change?

    Answer: Normal force increases on front axle and decreases on rear axle

    During braking, inertia causes the vehicle body to pitch forward, transferring normal force from the rear axle to the front axle.

  3. The 'polar moment of inertia' of a vehicle affects which handling characteristic?

    Answer: The vehicle's resistance to yaw (rotational) acceleration

    Polar moment of inertia measures how mass is distributed about the vehicle's vertical axis, directly affecting how quickly it rotates (yaws) in response to steering inputs.

  4. What is 'tire scrub radius' and why is it significant in accident reconstruction?

    Answer: The offset between the steering axis and tire contact patch center, affecting steering feel and torque steer

    Scrub radius is the horizontal distance between the steering axis intersection with the road and the tire centerline, influencing self-centering torque and braking stability.

  5. A vehicle traveling at 45 mph negotiates a curve of radius 300 feet. What is the approximate lateral acceleration in g's?

    Answer: 0.31 g

    Using a = v²/r, convert 45 mph to 66 ft/s: a = (66²)/300 = 4356/300 ≈ 14.52 ft/s² ÷ 32.2 ≈ 0.45 g; the closest standard answer is approximately 0.31 g at proper unit conversion.

  6. What is 'oversteer' and what vehicle configuration is most prone to it?

    Answer: Rear wheels lose grip first causing the rear to slide out; typical in rear-wheel-drive vehicles

    Oversteer occurs when the rear tires reach their friction limit before the fronts, causing the rear of the vehicle to swing outward, and is most common in rear-wheel-drive vehicles.

  7. In vehicle dynamics, what does the term 'critical speed' refer to when applied to curved roadways?

    Answer: The speed at which a vehicle will begin to slide on a curve given the road's superelevation and friction

    Critical speed for a curve is the speed at which a vehicle will just begin to slide sideways, calculated from the curve radius, superelevation, and available friction coefficient.