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Chapter 3, Section 6Conservation of Momentum
Date: 2/6/12HW: 3.6 PTG #1-16, pg. 319-320
Learning Objective:• Describe conservation
of momentum in collisions
Success Criteria:• Calculate momentum in
a system• Define conservation of
momentum in words and equations
Do Now:• Copy LO and SC on new
left side page• WDYS/WDYT pg. 310
Agenda:• Do Now• PhET/Investigate• Physics Talk• PTG• Summary/Quiz
Investigate: Collision PhET
collision-lab_en.jar
Mass of Object 1 (kg)
Mass of Object 2 (kg)
Velocity of Object 1 before collision (m/s)
Velocity of Object 2 before collision (m/s)
Mass of combined objects after collision (kg)
Velocity of combined objects after collision (m/s)
1.0 1.0 0.0 2.0
2.0 1.0 0.0 3.0
1.0 2.0 0.0 3.0
Momentump=mv
Before Collision After Collision
Momentum of Object 1 kg*(m/s)
Momentum of Object 2 kg*(m/s)
Momentum of Combined objects 1 and 2 kg*(m/s)
Physics Talk 3.6 What is the
Conservation of Momentum?
The total momentum before a collision, is equal to the total momentum after the collision if no external forces act on the system.
What is the equation for momentum?
What is the equation for conservation of momentum?
p=mv• p=momentum
[kg*(m/s)]• m=mass (kg)• v=velocity (m/s)
Why is this equation written like this?
You added the masses after the collision because they stuck together
Pool ball example Single cue ball hits a rack of 15 balls…momentum is conserved!
Total momentum before is equal to the total momentum after the collision
The balls move in new directions with new speeds, but the momentum stays the same!
Why is conservation of momentum important?
Used to investigate traffic accidents
If you know masses and velocities of two objects, you can predict the velocity after the collision…you can predict the future!
2/8, 2012HW: Grade Report Signed
Learning Objective:• Describe conservation
of momentum in collisions
Success Criteria:• Calculate momentum in
a system• Define conservation of
momentum in words and equations
Do Now:• 10 minutes to complete
packet
Agenda:• Do Now• PhET/Investigate• Physics Talk• PTG• Summary/Quiz
Practice Problems PTG pg. 319 #1-16
Essential Questions LO and SC
Reflection Answer essential
questions pg. 318
Quiz!