Collision Course:
Elastic and Inelastic Collisions
Corina Bot, PhD (NJIT, C2PRISM)Keri Salvador (NJIT, C2PRISM)Caroline Savio (ESHS, NPS)
Career DayMay 11th, 2010
Outline of Presentation
About Collision Course Applet
Lesson Plan in Conjunction with Applet
Conclusion and Questions
Concepts Behind Collision Course Applet
Used to distinguish elastic and inelastic collisions
Conservation of momentum
ffii
ffii
vvvv
vmvmvmvm
2121
22112211
momentum before collision = momentum after collision
results before = results after
Elastic collision Conservation of momentum
m1v1i m2v2i m1 m2 v fmomentum before collision = momentum after collision
Inelastic collision Conservation of momentum
results before = results after
Introduction to Collision Course Applet
Designed by C2PRISM Fellow Corina Bot, PhD. Dr. Bot interviewed six Advanced Placement Physics
students at once via focus-group .
Students really liked the idea of acquiring a physics concept shaped as a game.
Features of Collision Course Applet
Multiple choice question game Takes place in neutral settingPlayer chooses which car to driveContains sound effectsVisible damage in the cars after collisionsCartoon policeman assigns ticket at collision
scene Player must distinguish whether collision was elastic or
inelastic A correct answer -> policeman gives you points and your
ticket is void An incorrect answer -> policeman gives you a ticket and
you lose points
Specifics on Applet Creation
Java applet developed by software engineer students at NJIT
Flash software/plug-in required
PC and Mac OS Compatible
Outline of Presentation
Lesson Plan in Conjunction with Applet
Lesson Plan in Conjunction with Applet
Engagement and Assessment
Ideally, students work independently on applet using computers in lab classroom. If there are not enough computers in classroom, work
in pairs. Or perform applet in computer lab instead of physics
lab.
Formative Check The applet consists of multiple choice questions that
evaluate the student’s understanding of types of collisions.
Lesson Plan in Conjunction with Applet
Some practice problems Mario and Luigi on Bumper Cars
The physics classroom http://www.physicsclassroom.com/Class/momentum/u
4l2d.cfm
Elastic collision Input: m1 = 300 kg m2 = 400 kg v1i = 20 km/h v2i = 0 km/h
Calculate: v1f =? v2f = ?
Momentum is conserved!
Solution
h
km
h
km
h
km
h
kmvv
h
km
h
kmv
vkgh
kmkg
h
kmkgvkgvkg
h
kmkg
h
kmvkgvkg
h
kmkg
h
kmvv
vvh
km
vkgvkgh
kmkg
vkgvkgh
kmkg
vvvv
vmvmvmvm
ff
f
f
ff
ff
ff
ff
ff
ff
ffii
ffii
14.172085.220
85.2700
2000
7002000
80004003006000
204003006000
)4(20
020
)3(4003006000
400300020300
)2(
)1(
12
1
1
11
11
12
21
21
21
2121
22112211
Substitute values given in problem into equation (1):
Substitute values given in problem into equation (2):
Substitute equation (4) in equation (3):
Inputs: m1 = 300 kg m2 = 400 kg v1i = 20 km/h v2i = 0 km/h
Calculate: v1f=? v2f = ?
Inelastic collision
Input: m1 = 300 kg m2 = 400 kg v1i = 20 km/h v2i = 0 km/h Calculate: vf = ?Calculate: momentum before & after collision
Momentum is conserved!
Solution
h
km
h
kmv
vkgh
kmkg
vkgkgh
kmkg
vmmvmvm
f
f
f
fii
57.8700
6000
7006000
400300020300
212211
h
kmkg
h
kmkg
h
kmkgkg
h
kmkg
vmmvmvm fii
59996000
57.8400300020300
212211
momentum before collision = momentum after collision
Inputs: m1 = 300 kg m2 = 400 kg v1i = 20 km/h v2i = 0 km/h
Calculate: vf=?
Conclusions
Many senses engaged in learning process Group discussion with class Group instruction with visual demonstration Independent work on applet and on practice problems Paired work (optional)
Students will qualitatively and quantitatively distinguish elastic from inelastic collisions.
Questions?
Thank You!
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