Momentum – Collision Lab
PSI AP Physics C – Momentum
Name:
Objectives:
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Date:
Investigate the relationships between the momentum and kinetic energy in
inelastic collisions
Investigate the relationships between the momentum and kinetic energy in
perfectly elastic collisions
Materials:
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Computer
Procedure:
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This lab is based on Interactive Simulations from the University of Colorado at
Boulder. Use your web browser to go to: https://phet.colorado.edu/sims/collisionlab/collision-lab_en.html
Click on the link above.
Select “Introduction.”
For each run:
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Click “Reset all.”
Select the following:
Velocity vector
Momentum vector
Kinetic energy
More data
Move elasticity slider to the left “Inelastic”
Part I Inelastic Collisions
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M1
0.5
2
1.5
1
Set masses and velocity with the values given in the table below.
Run each trial and record measured values in the table below, symbol (‘) is
related to all values after the collision, all masses are given in kg, velocities in
m/s and energies in J.
M2
1.5
2
0.5
2
V1
1
1
2
2
V2
0
0
0
-3
V1’
.25
.5
1.5
-1.3
www.njctl.org
V2’
.25
.5
1.5
-1.3
P1
.5
2
3
2
PSI AP Physics C
P2
0
0
0
-6
P1’
3.13
1
2.25
-1.33
Momentum
P2’
0.38
1
0.75
-2.67
KE
.25
1
3
11
KE’
.06
0.5
2.25
2.67
Momentum – Collision Lab
PSI AP Physics C – Momentum
Follow up questions:
1.
Is momentum conserved in inelastic collisions? Explain w/ example.
Yes, momentum is conserved in elastic collisions because the balls stick
together. In trial 2, the initial momentum was a total of 2 kg*m/s and the final
momentum was a total of 2 kg*m/s.
2.
Is kinetic energy conserved in inelastic collisions? Explain.
No, because the balls stick together. In trial 2 the initial kinetic energy was 1
Joule and the final kinetic energy was 0.5 Joules.
3.
How do different values of masses and initial velocities affect the final momenta
of the two objects?
The masses and the initial velocities affect the proportion of the final momentum
between the balls. Momentum is mass times velocity (p = mv), higher values of
masses and velocities will result in more final momenta for the objects, the lower
values will create less final momenta. This can in Trials 2 and 3 where an increase
in velocity led to more momentum in Trial 3 than in Trial 2.
Part II Elastic Collisions
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M1
0.5
Move the elasticity slider to “elastic” collisions.
Set masses and velocity with the values given in the table below.
Run each trial and record measured values in the table below, symbol (‘) is
related to all values after the collision; all masses are given in kg, velocities in
m/s and energies in J.
M2
1.5
V1
1
V2
0
V1’
-.5
www.njctl.org
V2’
.5
P1
0.5
PSI AP Physics C
P2
0
P1’
P2’
-0.25 0.75
Momentum
KE
0.25
KE’
0.25
Momentum – Collision Lab
PSI AP Physics C – Momentum
2
1.5
1
2
0.5
2
1
2
2
0
0
-3
0
1
1
3
-4.67 .33
2
3
2
0
0
-6
0
2
1.5
1.5
-4.67 0.67
1
3
11
1
3
11
Follow up questions
4.
Is momentum conserved in elastic collisions? Explain.
Yes, momentum is conserved in elastic collisions because the final momentum,
as seen in Trial 1, is the sum of the initial momentums of the two objects, which
means that momentum was conserved.
5.
Is kinetic energy conserved in elastic collisions? Explain.
Yes because energy is conserved in elastic collisions. Looking at Trial 1, the
initial energy, 0.25, is the same as the final kinetic energy, 0.25, displaying the
conservation of energy.
6.
How do different values of masses and initial velocities affect the final momenta
of the two objects?
Higher masses and initial velocities lead to more final momenta of the two
objects, as seen in Trial 4, where a mass of 1 and 2 and velocities of 2 and -3 led
to a higher magnitude of final momenta than any of the other trials. Smaller
masses and velocities generate smaller values for final momenta.
Part III Two dimensional collisions
Switch the set up to “Advanced.”
Move the elasticity slider to “elastic” collisions.
Set masses and velocity with the values given in the table below.
Run at least three trials for different masses and velocities including different
angles and record all values in the table below; symbol (‘) is related to all values
after the collision, all masses are given in kg, velocities in m/s and energies in J.
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M1
M2
P1x
P1y
P2x
P2y
P’1x
P’1y
.5
1.5
.591
.243
-1.501
-.212
-0.08
1
1.5
2
2
1.576
0.789
0.382
-0.882
1.113
1.113
1.154
1.154
1.210
1.555
-0.831 0.830
-0.105 1.480
-0.555 .347
www.njctl.org
PSI AP Physics C
Momentum
P2x’
P2y’
KE
KE’
0.862
1.17
1.17
1.641
.827
1.96
1.11
1.96
1.11
Momentum – Collision Lab
PSI AP Physics C – Momentum
Follow up questions
7.
Is momentum conserved in elastic collisions in two dimensions? Explain w/
examples.
Yes, momentum is conserved, as the sum of the initial momentum in the x and y
direction for both objects is the same as the sum of the final momentum in the x
and y direction of both objects. For example, in Trial 1, the sum of all momenta is
-0.879, which is equal to the sum of final momenta.
8.
Is kinetic energy conserved in elastic collisions in two dimensions? Explain.
Yes, kinetic energy is conserved in elastic collisions in two dimensions. In trial 1
the initial kinetic energy was 1.17 Joules and the final kinetic energy was 1.17
Joules.
9.
How do different values of masses and initial velocities affect the final momenta
of the two objects?
As momentum is conserved, higher values of masses and initial velocities that
lead to more initial momentum would generate higher final momenta as well. This
is seen in Trials 1 and 2, where Trial 2 has higher masses than Trial 1, it can be
seen that the sum of the momenta for Trial 2 was higher than Trial 1 (-0.879
compared to 4.225).
www.njctl.org
PSI AP Physics C
Momentum