Question

“Crash compatibility” refers to the tendency of vehicles to inflict more or less damage on another vehicle (the “collision partner” vehicle). Collisions that involve two vehicles that are incompatible tend to have a higher potential for serious injury than do collisions that involve compatible vehicles.

2

In general, lack of crash compatibility arises from three factors:

Mass Incompatibility: The conservation of momentum in a collision places smaller vehicles at a disadvantage when the collision partner is a heavier vehicle. For an inelastic head-on collision, a vehicle which is half the mass of its collision partner will experience a change in velocity double that of its collision partner.

Geometric Incompatibility: An example of this type of incompatibility is when a sports utility vehicle (SUV), with a relatively high ride height, collides with a car with a much lower ride height. In a frontal impact, a mismatch in the ride height of the colliding vehicles can lead to the misalignment of how the collision forces are applied to the vehicle structures. This may prevent the vehicle structures, such as crumple zones, from absorbing the energy of a crash as they are designed to do.

Stiffness Incompatibility: The stiffness of a vehicle is a measure that describes the relationship between the force of a collision and the amount the vehicle deforms as a result of this force. In a frontal collision between two vehicles of the same mass but with a mismatch in stiffness, the bulk of the crash energy would be absorbed by the less stiff vehicle resulting in greater deformation of the less stiff vehicle. From a compatibility perspective, the preferred scenario would be for both vehicles to share the crash energy rather than forcing one of the collision partners to absorb the bulk of the energy in the crash.

Two-Part Question

Multiple Choice Question

The following question has two parts. First, answer Part A. Then, answer Part B.

Part A:

Which claim is made by the author of the texts?

A. 

Vehicles that have the same mass can have very different linear stiffness values.

B. 

Collision partners are the two vehicles involved in a collision.

C. 

Geometrically incompatible vehicles have a higher risk for passenger injuries because of a difference in the masses of the vehicles.

D. 

Linear stiffness of a vehicle depends on the amount of deformation and velocity during a collision, but is independent of the mass of the vehicle.

Multiple Choice Question

Part B:

Which sentence from the texts best supports this claim?

A. 

The stiffness of a vehicle is a measure that describes the relationship between the force of a collision and the amount the vehicle deforms.

B. 

This results from the fact that for a given vehicle weight, vehicles display a substantial variation in the amount of crush, or front-end crumple, designed into the front structure.

C. 

Collisions that involve two vehicles that are incompatible tend to have a higher potential for serious injury than do collisions that involve compatible vehicles.

D. 

In a frontal impact, a mismatch in the ride height of the colliding vehicles can lead to the misalignment of how the collision forces are applied to the vehicle structures.

Answer 1

Part A: A

Part B: B

Brief justification: The text explicitly discusses a frontal collision "between two vehicles of the same mass but with a mismatch in stiffness," and sentence B states that for a given vehicle weight vehicles show substantial variation in front-end crush, supporting that same-mass vehicles can have different stiffness.