Physics
9/9/18
Motion with Constant Acceleration
Introduction:
In this lab, I used a simulation to measure the position and velocity of a cart as it
accelerated along a frictionless surface. This lab was a virtual lab, in which I calculated the
average velocity of the cart, and used velocity vs. time graphs to determine the acceleration of
the cart.
Purpose: Experimentally observe how an object’s position and velocity change while it is
moving with a constant acceleration.
Question: How does an object’s position and velocity change as the object accelerates?
Hypothesis: If the fan speed increases, then the acceleration of the cart increases, because a
greater fan speed supplies more energy to move the cart
Materials:

One computer with access to virtual lab
Materials within Virtual Lab:

Fan with three speeds
o Low
o Medium
o High

Cart

Odometer
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
Frictionless Surface

Track

Finish line after 500 meters

Timer
Procedure:
1. Before beginning gather up all of the materials listed in the above two lists.
2. Open the virtual lab simulation.
3. Select Low for the fan speed, and No Friction for the surface type.
4. Open the data tab and select the buttons Speed and Line graph.
5. Click the Play button. Let the cart run past the finish line.
6. Record the data from the Speed data table into Table A in the Low fan speed column.
7. Record the total distance to the finish line, and the total elapsed time in Table B.
8. Use the data in Table B to calculate the average velocity of the cart, and record the
answer in Table B using cm/s.
9. Look at the Speed vs. Time graph and determine the acceleration of the cart. Record
answer in cm/s2 in Table B.
10. Select the Position button to view the plot of Position vs. Time. Record a description of
the graph in table C.
11. Select the Speed button again and open the Experiment tab.
12. Select Medium for the fan speed, and click the reset button to start the cart at the
beginning of the track.
13. Repeat steps 4 and 5.
14. Record the data from the Speed data table into Table A in the Medium fan speed column.
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15. Repeat steps 7 through 11.
16. Select High for the fan speed, and click the reset button to start the cart at the beginning
of the track.
17. Repeat step 13.
18. Record the data from the Speed data table into Table A in the High fan speed column.
19. Repeat step 15.
20. Open the Data tab and select the Speed button.
21. Open the Experiment tab and select Low for the fan speed, and click the reset button to
start the cart at the beginning of the track.
22. Open the Data tab and locate the timer.
23. Click the play button to start the cart. Stop the cart at 4 seconds by hitting the Pause
button.
24. Open the Experiment tab and turn the fan speed OFF. Return to the Data tab and click on
the Play button to resume the cart’s run.
25. After the cart crosses the finish line, observe the plot of Speed vs. Time graph. Describe
how this graph differs from the earlier trials.
26. Record observations in Table D.
Data Collection and Organization:
Table A
Elapsed Time
(s)
0
Cart Speed
(Low fan speed)
(cm/s)
Cart Speed
(Medium fan speed)
(cm/s)
Cart Speed
(High fan speed)
0
0
0
(cm/s)
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1
18.0
24.0
32.0
2
36.0
48.0
64.0
3
54.0
72.0
96.0
4
72.0
96.0
128.0
5
90.0
120.0
160.0
6
108.0
144.0
7
126.0
Table B
Elapsed time to
finish line
Δt (s)
Total distance
Δx (cm)
Average velocity
Vavg = Δx/Δt
(cm/s)
Acceleration
a (cm/s2)
Low Fan Speed
Medium Fan Speed
High Fan Speed
7.4
6.4
5.6
500
500
500
67.6
78.1
89.3
18.0
24.0
32.0
Table C
Fan Speed
Low
Observations of Position vs. Time Graphs
Speed vs. Time is linear; Position vs. Time Graph is curved. The positions of the cart
are further apart because the velocity of the cart is increasing.
Medium
The graphs are similar to the graphs of the low speed fan, but the slope is steeper. The
cart moves further per second, so it takes less time to reach the finish line.
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High
The graphs are similar to the first two examples, but the slope is even steeper. Since
the speed was the greatest for this example the cart moves the farthest with each
second, so it takes less time to cover the distance.
Table D
Fan Speed
Low/OFF
Observations of Speed vs. Time Graph
The first part of the graph is a sloped line indicating an increase in speed over the first 4
seconds. The line flattens out after the first 4 seconds which means the speed no longer
increases. Since the fan was turned off the cart did not accelerate anymore.
Analysis:
The tables above show the acceleration, velocity, and position of the cart, with three different fan
speeds, and interpretation of the graphs. The table shows that the elapsed time of the cart was 7.4
seconds using low fan speed, 6.4 seconds using medium fan speed, and 5.6 seconds for high fan
speed. The Speed vs. Time graph is linear whereas the Position vs. Time graph is curved. When
the speed of the cart increases the slope gets even steeper. The slope of the line flattens out after
4 seconds when the cart loses acceleration.
Conclusion:
Overall, this experiment helped me to visualize how acceleration and speed affects the
movement of an object. I used the total distance traveled by the cart and divided it by the elapsed
time for each cart, to determine the average velocity for each cart. One possible error for this
experiment is that my calculations could be wrong, resulting in the wrong data. Another possible
error is that when I stopped the cart during the last trial, I did not stop the cart at 4 seconds. This
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could have thrown off my graph and my analysis of the graph. Overall I enjoyed this experiment
and am looking forward to doing more experiments like this.