2D CollisionsPhysics 12 Adv

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

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

2D Collision

A

B

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v=10.m/s

AB

v=?

2D Collisions

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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?

Elastic Collisions

1

2

1

2

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v’1= ?

v’2=?

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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

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

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

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?

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Practice Problems Page 509

Questions 35-37 Page 515

Questions 39-40 Page 524

Questions 41-45