Momentum (OCR GCSE Physics A, Combined (Gateway Science Suite)): Revision Notes
📚 Revision Notes
5.9.3 Collisions
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Example: Calculations involving momentum with a collision Two cars crash head-on into each other and both come to rest. The momentum after the crash is 0kg m/s. The diagram shows the velocities and masses of the two cars before the collision. Calculate the velocity of car A before the collision, . Momentum is conserved. [3 marks]
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Calculation If the momentum after the collision is 0kg m/s, then the momentum before the collision must also be 0kg m/s.
Therefore the momentum of the two vehicles must add up to zero. This means the momentum of each vehicle must be equal:
Using the momentum equation, :
Substitute in the values:
Rearrange to find the velocity of Car A: