Collision: Elastic & Inelastic Conservation of Momentum
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Transcript Collision: Elastic & Inelastic Conservation of Momentum
Collision Course:
Elastic and Inelastic Collisions
Corina Bot, PhD (NJIT, C2PRISM)
Keri Salvador (NJIT, C2PRISM)
Caroline Savio (ESHS, NPS)
Career Day
May 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
Elastic collision
Conservation of momentum
m 1 v1 i m 2 v 2 i m 1 v1 f m 2 v 2 f
v1 i v 2 i v1 f v 2 f
momentum before collision = momentum after collision
results before = results after
Inelastic collision
Conservation of momentum
m 1v1i m 2 v 2 i m 1 m 2 v f
momentum before collision = momentum after collision
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 setting
Player chooses which car to drive
Contains sound effects
Visible damage in the cars after collisions
Cartoon 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/u4l2d.c
fm
Elastic collision
Input: m1 = 300 kg
m2 = 400 kg
v1i = 20 km/h
v2i = 0 km/h
Calculate: v1f =? v2f = ?
Momentum
is conserved!
Solution
m 1 v1 i m 2 v 2 i m 1 v1 f m 2 v 2
v1 i v 2 i v1 f v 2
f
Inputs: m1 = 300 kg
m2 = 400 kg
v1i = 20 km/h
v2i = 0 km/h
(1)
f
(2)
Substitute values given in problem into equation (1):
km
300 kg 20
0 300 kg v1 f 400 kg v 2
h
6000 kg
km
300 kg v1 f 400 kg v 2
h
f
Calculate: v1f=? v2f = ?
f
(3)
Substitute values given in problem into equation (2):
km
20
h
v2
f
0 v1 f v 2
km
v1 f 20
f
(4)
h
Substitute equation (4) in equation (3):
6000 kg
km
300 kg v1 f 400 kg v1 f 20
h
km
h
6000 kg
km
300 kg v1 f 400 kg v1 f 8000 kg
h
2000 kg
km
h
v1 f
v2
f
700 kg v1 f
2000
km
700
h
v1 f 20
km
h
2 . 85
km
h
2 . 85
km
h
20
km
h
17 . 14
km
h
km
h
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
Inputs: m1 = 300 kg
m2 = 400 kg
v1i = 20 km/h
v2i = 0 km/h
m 1 v1 i m 2 v 2 i m 1 m 2 v f
300 kg 20
km
h
6000 kg
km
6000 km
700
Calculate: vf=?
700 kg v f
h
vf
0 300 kg 400 kg v f
8 . 57
h
km
h
momentum before collision = momentum after collision
m 1 v1 i m 2 v 2 i m 1 m 2 v f
300 kg 20
km
h
6000 kg
km
h
0 300 kg 400 kg 8 . 57
5999 kg
km
h
km
h
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!