MOMENTUM
1 mark · NormalWhich statement best describes how seat belts improve passenger safety in a car crash, using ideas about momentum?
- A.They increase the force acting on the passengers.
- B.They make the change in momentum larger.
- C.They increase the time over which momentum changes, reducing the force.
- D.They prevent the car from stopping suddenly.
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Correct option: They increase the time over which momentum changes, reducing the force.
Also accept: They increase the time taken for momentum to change, which lowers the force.
Common mistakes: Choosing options that do not mention time or force
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Marking points
B1 · 1 mark · Correct option identified.
Worked solution
Seat belts increase the time over which a passenger's momentum changes in a crash, so using F = Δp/t, the force experienced is reduced.