Crush zones make a car safer in a collision because they

Crush zones make a car safer in a collision because they

• A. They distribute the energy more evenly across the entire car
• B. They steadily increase rider protection by rigidly stiffening the body
• C. Increase the time of impact and decrease the force of impact
• D. They provide a rigid barrier to passengers

Answer: (C)

Crush zones absorb energy by deforming during a crash. This deformation lengthens the time over which the car slows down, so the deceleration is more gradual and the average force on occupants drops. Since impulse equals force times time, extending the impact time lowers the force experienced by passengers. Rigidly stiffening the body would prevent energy absorption and increase forces on occupants; a rigid barrier would also transfer more energy to people inside. The important point is that controlled deformation turns crash energy into work done by the structure, slowing the car safely.

Crush zones absorb energy by deforming during a crash. This deformation lengthens the time over which the car slows down, so the deceleration is more gradual and the average force on occupants drops. Since impulse equals force times time, extending the impact time lowers the force experienced by passengers. Rigidly stiffening the body would prevent energy absorption and increase forces on occupants; a rigid barrier would also transfer more energy to people inside. The important point is that controlled deformation turns crash energy into work done by the structure, slowing the car safely.