Lab: Uniform Accelerated Motion
Purpose: To determine the acceleration of the cart along the ramp by determining the velocity of the
cart at various positions along the track.
Variables:
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Manipulated Variable Position along the track, measured in meters relative to the top of the
track. (i.e. the top of the track would be equivalent to 0.000 m). Using the ruler attached to the
track to determine each position, and measuring to the nearest millimeter.
Responding Variable  Velocity at each position, calculated in meters per second. Using the
photogate timer attached to the track, the time required for the car to pass through the gate
will be measured. The gate will trigger the start of the timer when solid black bar on the plastic
“fence” attached to the car enters the gate, and will stop timing when the solid black bar leaves
the gate.
Controlled Variables:
o Starting position of the car, relative to the top of the track
o Angle of the track
o Length of the black bar used for timing
Materials:
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1 Vernier dynamics system: 1.2 m long steel track, 1 leveling foot, end-stop barrier, ring stand
support and stand clamp, photogate support stand
1 Vernier collision cart
1 plastic picket fence with solid black bar
1 Vernier Photogate Timer
1 LabQuest with USB cord
1 Laptop with LoggerPro
1 angle-measuring device (you may need to share with a neighboring group)
Set-up Procedure:
1. Attach the photogate to the support stand on the track . Make sure the height of the
photogate’s light beam is positioned so that it will pass through the solid black bar on the
cart and so that the cart will still be able to pass through under the gate.
2. Connect the photogate to the DIG 1 port on the LabQuest using the gate’s cord
3. Connect the LabQuest to the computer using the USB cable
4. Open LoggerPro on your computer, then:
a. Go to “fileopen”
b. Select the public server
c. Scroll to the IB Physics 1 folder and open that folder
d. Select the LoggerPro file titled “uniform accelerated motion 10.20.14” and open it
5. In LoggerPro, set up the photogate sensor:
a. Experimentset up sensors
b. Click on the picture of the photogate shown in the “DIG 1” port
c. Select “Gate Timing”, click OK
Data Collection Procedure
6. Measure and record the angle of track.
7. Measure and record the length of the black bar on the cart
8. Place the cart at the top of the track, in the position from which you’d like to consistently
release. Measure and record the starting position of the front of the cart (the downhill side
of the cart). Be certain to start at this same position each trial.
9. Position the photogate so that it is about 1 cm in front of the cart’s starting position.
Measure and record this position of the gate
10. Make a trial run of your cart.
a. Click the green “collect” button in LoggerPro
b. Release the cart from the starting position
c. Looking at the data collected, make sure that the photogate is collecting data for the
large black bar. Make note of any other data that has been collected due to
shadows, scratches, or other faults in the plastic fence so that you know what kind
of data to disregard in future runs.
11. Place the cart at its starting position at the top of the track. Clear all data from the previous
set of trials.
12. Click the green “collect” button in LoggerPro
13. Release the cart and let it roll freely through the gate.
14. Pick up the cart, remove it from the track and replace it at the starting position.
15. Repeat steps 12 and 13 until you have 5 trials for that gate position.
16. Click “Stop” in LoggerPro in order to stop the data collection.
17. Record in your lab book data table the times that have been measured corresponding to the
5 times that the large black bar passed through the photogate.
18. Move the photogate to a new position approximately 6-8 cm further along the track.
Measure and record this new position relative to the top of the track.
19. Repeat steps 10-16 for this new gate position.
20. Repeat steps 17 – 18 until you have reached a position that is a little more than a cart’s
length from the bottom of the track. You may need to catch the cart at the bottom to
prevent it from bouncing back through the gate for some of the later runs.
Procedure for determining an “accepted” value for your acceleration
21. Tape the low-g accelerometer to the top of the cart so that the arrow on the sensor points
directly down the track.
22. Unplug the photogate from the LabQuest, and open a new, blank file in LoggerPro.
23. Plug the accelerometer into an appropriate port.
24. Press the “collect” button in LoggerPro
25. Release the cart from the top of the track and let it roll to the bottom of the track. Press the
“stop” button in LoggerPro
26. Select the part of the graph that corresponds to the time that the cart was freely rolling
down the track
27. Using the statistics tool, determine the average acceleration of the cart while it was freely
rolling.
28. Repeat steps 24 – 27 for a total of 5 trials.