1. 2D Collisions
Physics 12 Adv

2. 2D Collisions In all collisions, momentum is conserved
In elastic collisions, kinetic energy is also conserved
As momentum is a vector, we can break momentum into components and employ the conservation of momentum

3. 2D Collision
Two cars approach an intersection; the first car is travelling east at a velocity of 15m/s and the car has a mass of 1000.kg. The second car is travelling north at a velocity of 10.m/s and has a mass of 1200.kg. If the cars collide and stick together, determine the following:
The velocity immediately after the collision
The direction of motion immediately after the collision

4. 2D Collision
v=15m/s
v=? A A B
v=10.m/s B

5. 2D Collisions

6. Elastic Collisions
A proton travelling with speed 8.2x105m/s collides elastically with stationary proton in a hydrogen target. One of the protons is observed to be scattered up at a 60.° angle.
At what angle will the second proton be scattered?
What will the speed of each of the protons be after the collision?

7. Elastic Collisions
v’1= ? 1
v1= 8.2x105m/s 1 2 2
v’2=?
Before
After

8. Kinetic Energy

9. Momentum

10. Three Equations, Three Unknowns

11. In Equations 2 and 3, take v’1 to left and square both sides

12. Add the final steps from the last step then substitute equation 1

13. Use the answer for v’1 to solve for v’2 and angle

15. Ballistic Pendulum
In a ballistic pendulum, there are components where energy is conserved and components where it is lost
It is therefore important that we analyze each component of the system correctly

17. Inelastic Collision
The first part of the analysis involves the inelastic collision between the projectile and the bob
We know that as it is an inelastic collision, momentum is conserved but energy is not

18. Pendulum
After the collision, the projectile and bob act as a pendulum and will swing to a maximum height
If this height can be measured, then through the conservation of energy, we can determine the speed of the projectile and bob immediately after the collision

19. Question
A forensic expert needed to find the velocity of a bullet fired from a gun in order to predict the trajectory of a bullet. She fired a 5.50g bullet into a ballistic pendulum with a bob that had a mass of 1.75kg. The pendulum swings to a height of 12.5cm above its rest position before dropping back down. What was the velocity of the bullet before it hit and became embedded in the bob?

20. Analysis

21. Analysis

22. Practice Problems Page 509 Page 515 Page 524 Questions 35-37