MOMENTUM

3 marks · Normal

Explain how crumple zones in cars help to reduce injuries to passengers during a collision, using ideas about momentum.

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Must show: Increase collision time, reduce force, change in momentum stays the same

Also accept: Reference to seat belts as needed

Common mistakes: Only mentioning absorption of energy, not linking to time or force

Show mark scheme and worked solution

Marking points

B1 · 1 mark · States that crumple zones increase the time taken for the car to stop (collision lasts longer).

B2 · 1 mark · States that the change in momentum is the same (car stops).

B3 · 1 mark · Explains that increasing time reduces the force on passengers (since F = Δp / t).

Worked solution

Crumple zones increase the time taken for the car to come to rest during a collision. This means the same change in momentum happens over a longer time. Since force equals change in momentum divided by time, increasing the time reduces the force on the passengers, reducing injuries.