Kinematics in One Dimension

Pre-Lab Checklist
Experiment Notes: Things to keep in mind while performing the experiment.
Analysis Notes: Questions to answer in your analysis of theexperiment
Grading Breakdown
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Pre-Lab Checklist:

Because this is the first lab of thesemester, the checklist has been filled in for you (in italics) as an example. You will be asked to complete the checklist yourself for future experiments.

1. Describe the situation to be studied in this experiment.

An air cart is accelerated down an inclined air track. We will betiming the motion for several distances in order to calculate the averagevelocities and the acceleration of the motion.

2. List and define each of the parameters to be measured directly.

x_o= the position of the cart when timingstarts = the distance from the front edge of the cart at the launch position tothe first photogate

S = the distance between the photogates

t = the time it takes the cart to travel from the firstphotogate to the second photogate (This is measured directly by the computer.)

3. List and define any quantities that will be calculated.

(S/t) = the average speed of the cart as it travelsfrom the first photogate to the second photogate
v_o = the instantaneous speed of the cart as it enters the first photogate
v = the instantaneous speed of the cart asit enters the second photogate
a = the acceleration of the cart
t_o = the time of the cart's release (Thiswill be a negative number because t=0 is set as the time the cart enters thefirst photogate.)

4. List any graphs that will be made during the analysis.

S versus t
(S/t) versus t
v versus t

Experiment Notes

1. Make sure that the track is level and that the cart is low friction.

2. Photogate #1 should be ~10 cm from the UPPER end of the inclined airtrack. It will remain in this position for the entire experiment. Measure andrecord the exact distance.

3. Photogate #2 will have five different positions, each measured from thefirst photogate. Try to keep the photogate the same distance above the track asyou move it, so that S will be measured parallel to the cart's motion onthe track.

4. Always release the cart from the same position and in the samemanner. Use the consistency of the time measurements as a gauge for theconsistency of your release.

5. You will be using the Pasco 500 Interface. To take data, the computerneeds to know which sensor it will be useing. Follow the steps listed here toget you computer ready to take data.

Click and drag the stereo-jack icon to Digital Channel #1.
There will be a pop-up menu showing the possibilities for the digitalsensors. Choose Photogates(2). This will alert the computer that youwill be using two photogates.
A second pop-up menu will appear, asking you to input the length of theobject and the distance between the photogates. In this instance it doesn'tactually matter whqat we enter for these values because we are only interestedin obtaining the time between the photogates. The requested length anddistance would be relevant in other situations, but are not necessary in thiscase. You won't need to worry about changing these parameters when you changethe distance between the photogates.
Now click and drag the table icon to Digital Channel #1. This will tellthe computer to put all the data directly in the table. Choose the TimeBetween Photogatess from the options menu.
Hit the key in the Pasco 500 window. This will let you monitor thesystem without saving any data. Use your hand to check the photogates. Thecomputer should be showing the time it took your hand to move from Photogatte#1 to photogate #2. Make sure that photogate #1 is at the top of theslope!
Hit the REC key to start recording data. Hit the STOP key tostop recording data after five runs. The times for each individualrun will show up in the table. Record the times for the five trials at 20 cmgate separation into your data tabe.
Open an new data table to take data for 40 cm gate separation. Repeat thisfor separations of 60 cm, 80 cm, and 100 cm.

6. Graph #1: S as a function of time. S is on the verticalaxis and time is on the horizontal axis. DO NOT CONNECT THE DOTS! Plot asmooth curve through the data. (Not necesesarily a straight line.)

7. Make a calculation table before plotting the next two graphs. Rememberthat (S/t) is the average speed while v is the final speed of thecart as it leaves the second photogate.

Calculation Table for Kinematics in One Dimension.
S t_avg S/t ** v=v_o+at
20 cm

40 cm

60 cm

80 cm

100 cm

** NOTE: v_o and a are calculated from the interceptand slope of the (S/t) graph.

Analysis Notes

1. Your results section should include your values of v_o,a, and t_o.

2. Why was it necessary to release the cart in the same way each time? Did the orientation of the cart matter? Didthe method of release matter? Discuss the arangement of the equipment and statewhat methods you used to keep the releases consistent.

3. Discuss the methods you used to obtain your values ofv_o, a, and t_o.

4. Were the shapes of your graphs consistent with the coresponding kinematicequations? Explain how you know whether or not they corespond.

5. Were your two values for t_o the same? Should they be? Why or why not?

Grading Breakdown

Section	Points
Purpose	1
Results	3
Graphs	6
Calculations	2
Discussion	8

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