# P2 3.6 Impact forces and 3.7 Car safety

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Impact forces

Key points and Learning objectives:

When vehicles collide what does the force of the impact depend on?

• When vehicles collide, the force of the impact depends on mass, change of velocity, and the duration of the impact.

How does the impact force depend on the impact time?

• The longer the impact time is, the more the impact force is reduced.

What can we say about the impact forces and the total momentum when two vehicles collide?

• When two vehicles collide they exert equal and opposite forces on each other and their total momentum is unchanged assuming no external forces act.

If we know the impact time we can then work out the impact force so you

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