1. A LEVEL PHYSICS Year 1 Momentum A* A B C
B/C Target
A/A* Target EP
AEP C B A A*
Recall that Momentum = mass × velocity (grade D)
Understand the conservation of linear momentum (grade B).
Apply the conservation of momentum quantitatively to problems in one dimension (grade B).
Elastic and inelastic collisions; explosions (grade B).
Appreciation of momentum conservation issues in the context of ethical transport design (grade A).

2. Momentum
“The tendency of the object to keep moving in the same direction” …how difficult it is to stop the object…

3. Linear Momentum
Your momentum depends on two things – mass and velocity! Momentum = mass x velocity Units? Vector or scalar quantity?

5. Only applies if forces come from the objects
Can be used to describe collisions/ explosions
If friction or other external forces act its not conserved
Momentum
Assuming no external forces act, linear momentum is always CONSERVED…
This means the toal linear momentum of two objects before they collide equals the total linear momentum after the collision.
Total momentum before = Total momentum after
The same principle can be applied to situations where there is not a collision – like explosions.

6. Why is the velocity of the gun much less than the bullet?

7. A car of mass 1250kg is travelling at 20m/s
A car of mass 1250kg is travelling at 20m/s. It collides with a car in front of mass 1000kg travelling at a speed of 10m/s in the same direction. The two cars coalesce and move off at the same velocity. What is the new velocity?

8. A car of mass 1250kg is travelling at 20m/s
A car of mass 1250kg is travelling at 20m/s. It collides with a car in front of mass 1000kg travelling at a speed of 10m/s in the same direction. The two cars coalesce and move off at the same velocity. What is the new velocity?

9. Elastic and Inelastic Collisions
Linear momentum and kinetic energy are conserved.
No energy is dissipated as heat, sound, etc.
Linear momentum is conserved and some kinetic energy is conserved.
Collisions between gas particles are elastic – otherwise the air would get colder and colder until there’s no motion or heat left!

10. Questions 1-3 page. 151
Answers in the back