Download 1 - CSUN.edu

If a section is highlighted, it needs your attention. Do not turn in your lab with anything highlighted!
Names
1. Title-Newton’s Second Law of Motion Lab
2. Purpose-The purpose of this experiment is to determine the relationship between force, mass, and
acceleration
Questions:
a. What is the relationship between net force and acceleration (assuming mass is constant)?
b. What is the relationship between mass and acceleration (assuming net force is constant)?
3. Hypothesis (predictions)
a. I predict that…
b. I predict that…
4. Procedure
1.Choose an object that you will use to test your hypotheses. Calculate kinetic friction of the object
you will be using for table B.
2.Decide on three NET forces you will be testing. For example you can test the net forces of 2N, 4N,
and 6N. Write these net forces in time table B.
3. Draw the three free body diagrams in table B that depict what you will test. See the free body
diagram in table B for a sample.
4. Test the acceleration of the object by pulling it with the applied force that you input to your three
free body diagrams. Make sure you are pulling with the appropriate applied force. Keep the force
constant. This can be difficult and may take a few practice runs.
5. Record the times in Time Table A below.
6. Calculate the velocity and acceleration in Table B using the times from Time Table A. Remember
that velocity=displacement/time and acceleration=change in velocity/time
7. Calculate the percent error in table C.
8. Repeat the steps above for table D,E,F. Be sure to keep NET FORCE CONSTANT and increase
mass while experimenting to find the answer for question b. You will need to recalculate the kinetic
friction every time you add more mass.
5. Data Tables-Complete the data tables. Note that you can choose the net force you wish to apply. I might
recommend 1, 2, 3 or 0,1,2 or 0, .5,1, or any combination that is possible with the object you have chosen to
use. To measure acceleration you must measure velocity over at least two different adjacent intervals. I would
suggest measuring the time it takes to displace the object over the first 200cm (0-200cm), second 200 cm (200400cm), and third 200 cm (400-600cm) or the first 100 cm (0-100cm), second 100 cm (100-200 cm), and third
100 cm (200-300cm).
The numbers and free body diagrams below are examples.
Table A-Times for Measuring Acceleration for table B
Trial
Net Force
Time from 0-1m (s)
1
2
Time from 1-2m (s)
Total time from 0-2m (s)
3
1
Dependent Variable
Acceleration (m/s/s)
Net Force (N)
Trial #
Table B-Force and Acceleration Relationship
Independent Variable
Controlled
Variable
Free Body Diagram
Mass (g)
2
Example:
Fnorm=92 N
Ffric=3N
Constant=
Initial
Velocity
(m/s)
Fapp=5N
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
O
Fgrav=92N
2
4
Constant=
Initial
Velocity
(m/s)
O
3
6
Constant=
Initial
Velocity
(m/s)
O
Table C-Force and Acceleration Error from table B.
Net Force1
Measured Average Acceleration (m/s/s)2 Calculated Acceleration (m/s/s)3
% Error4
1. Input the values from the “net force” column in table A.
2. Input the values from the “average acceleration” column in table A.
3. Calculate acceleration using the formula ‘Force=mass*acceleration’. Use the force values from the “net
force” column in table A and the mass values from the “mass” column in table A (these values should be
the same throughout this column). Solve for acceleration.
4. Calculate percent error by the following formula:
((Measured Average Acceleration-Calculated Acceleration)/Calculated Acceleration)*100
Table D-Times for measuring acceleration in table E.
Trial
Mass
Time from 0-1m (s)
1
2
3
Table E-Mass and Acceleration Relationship
Time from 1-2m (s)
Total time from 0-2m (s)
Independent
Variable
Mass (g)
Controlled Variable
Dependent Variable
Net
Force
Acceleration (m/s/s)
Free Body Diagram
Consta Example:
nt= 1
Ffric=.75N
Fnorm=3.5N
Initial
Velocity
(m/s)
Fapp=1.75
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
Velocity
from 0-1
m
(m/s)
Velocity
from 1-2
m (m/s)
Average
Acceleration
(m/s/s)
O
Fgrav=3.5N
Consta
nt=
Initial
Velocity
(m/s)
O
Consta
nt=
Initial
Velocity
(m/s)
O
Table F-Mass and Acceleration Error for Table E.
Mass1
Measured Average Acceleration (m/s/s)2 Calculated Acceleration (m/s/s)3
% Error4
1. Input the values from the “mass” column in table C.
2. Input the values from the “average acceleration” column in table C.
3. Calculate acceleration using the formula ‘Force=mass*acceleration’. Use the mass values from the
“mass” column in table C and the force values from the “net force” column in table C (these values
should be the same throughout this column). Solve for acceleration.
4. Calculate percent error by the following formula:
((Measured Average Acceleration-Calculated Acceleration)/Calculated Acceleration)*100
Observations-Make your own observations about the acceleration, mass, and force applied in your experiments.
Make sure you record in bullet points or in a table.
5. Results (graph here) Click on insert, picture, and chart.
Force and Acceleration Graph (use an x-y scatter plot with force on the x-axis and acceleration on the y-axis;
see sample below)
Acceleration (m/s/s)
Force vs Acceleration
0.8
0.6
0.4
0.2
0
0
2
4
6
8
Net Force (N)
Mass and Acceleration Graph (use an x-y scatter plot with mass on the x-axis and acceleration on the y-axis; see
sample below)
Acceleration (m/s/s)
Mass vs Acceleration
0.8
0.6
0.4
0.2
0
0
10
20
30
40
Mass (kg)
7. Conclusion-FOLLOW THE RERUN FORMAT and address the questions! When you are finished, post
your lab on your UNIT 2 webpage! Also, remember to post your conclusion on nicenet! No paper needed!