1. Summarize what you did in Tuesday’s collision activity.
BELL RINGER 12/8:
Summarize what you did in Tuesday’s collision activity.
OBJECTIVE: SWBAT define conservation of momentum; SWBAT define and calculate for inelastic collisions
AGENDA:
Notes
Group Practice
Exit Ticket
HOMEWORK: 1-5, 7-8a on Worksheet

2. Conservation of Momentum
Momentum in a system is conserved
Pfinal=Pinitial
In general, for two objects that are colliding, the equation looks like:
m1v1 + m2v2 = m1v1 + m2v2
But, the equation is rearranged or changes slightly depending on the type of collision!
initial
final

3. Applying conservation of momentum
EX: Two ice skaters meet in the center of the rink and come to rest. They now push off against one another. One skater, with a mass of 54-kg, acquires a speed of m/s. What is the speed of the other skater, whose mass is 61-kg?

4. Conservation of Momentum + Collisions
Momentum in the system (objects colliding) is conserved as long as there are no external forces acting on the system
That doesn’t mean momentums within the system don’t change; the sum remains the same, but momentum will transfer b/w objects

5. COLLISIONS There are two types of collisions:
Inelastic: momentum is conserved, but kinetic energy is not; objects stick together upon collision. When the maximum amount of KE is lost to other forms of energy, it is called a completely inelastic collision.
2. Elastic: momentum and kinetic energy are conserved

6. INELASTIC COLLISIONS
Note: one object won’t always start at rest, so the m2v2 term can come back!
When one object starts at rest and the objects stick together after the collision and have the same final velocity, the equation is rearranged to:
m1v1 + m2v2 = m1v1 + m2v2
m1v1 = (m1 + m2) v

7. INELASTIC COLLISIONS
EX: On a touchdown attempt, a 95.0-kg running back runs to the right towards the end zone at 3.75 m/s. An 111-kg linebacker moving to the left at 4.10 m/s meets the runner in a head-on collision. If the two players stick together, what is their velocity immediately after the collision?

8. Answer Choices for Question 4:
BELL RINGER 12/5:
STANDARD: EMI 601
Answer Choices for Question 4:
OBJECTIVE: SWBAT solve collision problems using the conservation of energy equations
AGENDA:
Group Practice
Start Problem Set
HOMEWORK: Problem Set due Monday (check your ); QUIZ MONDAY!

9. What is the general equation for conservation of momentum?
BELL RINGER 12/5:
What is the general equation for conservation of momentum?
OBJECTIVE: SWBAT solve collision problems using the conservation of energy equations
AGENDA:
Group Practice
Start Problem Set
HOMEWORK: Problem Set due Monday (check your ); QUIZ MONDAY!

10. REVIEW
A train with a mass of 3500-kg is traveling at 20 m/s when it collides with another train that has a mass of 2700-kg and is traveling 15 m/s. If the objects stick together upon collision, what will be the trains’ velocity right after colliding?

11. GROUP PRACTICE