Momentum (AQA GCSE Physics Combined Science): Revision Notes
📚 Revision Notes
5.9.1 Momentum
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Momentum: All moving objects have momentum. If an object is not moving, the momentum is zero.
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Formula
Where is the momentum in kilogrammes metres per second , is the mass in kilogrammes (kg), and () is the velocity in metres per second .
Conservation of Momentum
- In a closed system, the total momentum before an event is equal to the total momentum after an event.
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Example: The backwards momentum of a cannon is equal to the forwards momentum of the cannonball.
- Momentum is always conserved in a collision or explosion (where there are no external forces like friction, air resistance, electrostatic attraction, etc.).
- In collisions:
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Example: Two marbles colliding; each will have momentum before and after the collision.
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Remember, momentum is a vector.
Changes in Momentum (Physics Only)
Newton's Second Law
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Force is equal to the rate of change of momentum.
Where is the force, is the final momentum, is the initial momentum, and is the time.