ACTAR Crash Dynamics 4

Question 1

What does the term 'delta-V' represent in vehicle collision analysis?

Accepted Answer

The change in velocity experienced by a vehicle during the collision event

Answer

Delta-V is the vector change in velocity a vehicle undergoes during the impact phase, a key metric for severity assessment and occupant injury evaluation.

Question 2

When a vehicle understeers during a pre-crash avoidance maneuver, the front tires are operating:

Accepted Answer

At or beyond their lateral force capacity, causing the vehicle to push wide

Answer

Understeer occurs when front tire lateral forces are saturated, causing the vehicle to follow a path with a larger radius than the steering input commands.

Question 3

In the context of a side-impact collision, the 'struck side stiffness' is generally lower than frontal stiffness because:

Accepted Answer

Vehicle door structures lack the longitudinal frame rails present at the front and rear

Answer

Vehicle doors and side panels lack the strong longitudinal frame rails and crumple zone design present at the front, making them structurally less stiff and leading to greater intrusion per unit energy.

Question 4

Which of the following conditions would cause an analyst to OVERESTIMATE pre-impact speed when using skid mark analysis?

Accepted Answer

Using a drag factor that is too low

Answer

Using a drag factor that is too low underestimates the decelerating force, requiring a higher computed speed to produce the observed skid length, thus overestimating speed.

Question 5

A vehicle traveling uphill on a grade of 5% has an effective drag factor that is:

Accepted Answer

Increased by 0.05 compared to level road

Answer

On an uphill grade, gravity adds resistance to braking, so the effective drag factor increases by the grade value (expressed as a decimal), e.g., f_eff = f + 0.05.

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

ACTAR Crash Dynamics 4