Physics - Momentum
OCR A-Level Physics 2022
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Definition and units of momentum
What is the word formula for momentum?
Relative magnitude of collisions
Two cars, $A$ and $B$ are travelling in the same direction at $30mph$ and $31mph$ respectively. What could be said about the “magnitude” of the collision?
It’s the same as a $1mph$ collision.
Two cars, $A$ and $B$ are travelling towards each other at $30mph$ and $31mph$ respectively. What could be said about the “magnitude” of the collision?
It’s a $61mph$ collision.
Conservation of momentum
What is the Principle of the Conservation of Momentum?
The total momentum of two objects before a collision is equal to the total momentum of the two objects after a collision.
How can the total momentum before and after an explosion be the same?
Momentum is a vector, each individual piece of shrapnel has a momentum that sums to zero.
Elastic and inelastic collisions
For an elastic collision, what is true about total energy?
It is conserved.
For an elastic collision, what is true about kinetic energy?
It is conserved.
For an inelastic collision, what is true about momentum?
It is conserved.
For an inelastic collision, what is true about total energy?
It is conserved, but transferred.
For an inelastic collision, what is true about kinetic energy?
It is _ _ not _ _ conserved.
Defining conservation of momentum precisely
How should you actually define the Law of Conservation of Momentum?
In a closed system, linear momentum is conserved in both directions.