MOM – C – Collisions – Explosions and Recoil - Lab
Name____________________________
SIMULATION
Go to essential-physics.com
Enter this code:
841 9439
Click on the “Investigations”icon Scroll down and click on “11A: Conservation of Momentum” Scroll down and click on the “iPhysics” icon -
- to launch the simulation
The law of conservation of momentum is a powerful generalization of Newton’s third law. For an isolated
system, the total momentum of all the objects inside is constant. In this investigation, you will explore the
conservation of momentum for two carts that are subject to no outside net force. The only catch is that the carts
have a compressed spring inserted between them! Is momentum conserved for this system?
Part 1: Conservation of momentum for spring-loaded carts
1. Select a mass for each cart.
2. Press [Run] to start the simulation.
3. Run the simulation for different combinations of masses for the two carts. Use your data table to record
the mass and velocity for each combination.
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Table 1: Tabulate the velocities and calculate the momentum and kinetic energy of each cart for masses 5,
10, and 15 kg. Use the results in this table to answer the questions below.
m1
v1
p1
m2
v2
p2
(kg)
(m/s)
(kg m/s)
(kg)
(m/s)
(kg m/s)
5
5
10
5
15
5
5
10
10
10
15
10
5
15
10
15
15
15
a. What similarities are there in the velocities and momenta when the masses of both carts are equal?
b. What is the difference in velocity when one mass is twice that of the other? When one mass is three
times the other?
c. What is the difference in momentum when the masses are equal? When one cart has twice the mass of
the other? When one cart has three times the mass of the other?
Applying new knowledge
1. Define the law of conservation of momentum in one sentence.
2. Explain the connection between Newton’s third law of action/reaction, and the law of conservation of
momentum for a closed, isolated system.
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PLUNGER CARTS
Procedure:
1. Using one cart with a retractable "plunger" and another cart
without a plunger, place the two carts on the track between the two
photogates. Push the retractable plunger into the plunger cart so
that it locks and does not pop out. Place the plunger end of the
plunger cart up against the other cart so that when you tap the peg
on the top of the plunger cart, the spring-loaded plunger pops out
and pushes the two carts apart, each passing through a photogate,
as seen in figure 1.
2. When you are ready to collect data, click on the Collect button
on the toolbar and lightly tap the peg on the top of the plunger
cart so that the spring-loaded plunger pops out and pushes the
two carts apart causing each cart to pass through a photogate.
3. Record the velocity of the carts in the data table for recoil on your student answer page for the time just after
they recoil away from each other.
4. Repeat the experiment for several more runs, adding various amount of mass to each cart to see how the
amount of mass affects the velocity and momentum of the carts before and after the collision. Remember to
record the data in such a way that another lab group can understand how you have organized your data and use it
to answer questions about your data
DATA AND OBSERVATIONS
Mass of one empty cart:
0.500 kg
Length of card: _______________ m
Fill in the data tables on the next page and answer
the questions
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Run
Mass of
Plunger
Car, m1
(kg)
Mass of
Second
Cart, m2
(kg)
1
2
3
4
5
Ru
n
1
2
3
4
5
Momentu
m p1 of
m1 before
collision
(kg m/s)
0
0
0
0
0
Momentu
m p2 of
m2 before
collision
(kg m/s)
0
0
0
0
0
Velocity
v1 of m1
Before
Collision,
(m/s)
0
0
0
0
0
Total
Momentu
m of
System
Before
Collision
0
0
0
0
0
Velocity
v2 of m2
Before
Collision
0
0
0
0
0
Momentu
m p1 of
m1 after
collision
(kg m/s)
Velocity
v1 of m1
After
Collision,
(m/s)
Momentu
m p2 of
m2 after
collision
(kg m/s)
Velocity
v2 of m2
Before
Collision,
(m/s)
Total
Momentu
m of
System
After
Collision
In general, does the data collected for the recoil of the two carts seem to verify the law of
conservation of momentum? Explain your answer and indicate which run of the recoil of the two carts best
conserves momentum
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