Momentum (AQA GCSE Physics Combined Science): Revision Notes
📚 Revision Notes
5.9.1 Momentum
Note
Momentum: All moving objects have momentum. If an object is not moving, the momentum is zero.
Note
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.
Example
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:
Example
Example: Two marbles colliding; each will have momentum before and after the collision.
Note
Remember, momentum is a vector.
Changes in Momentum (Physics Only)
Newton's Second Law
Note
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.