Updated: 8/09/2009
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Updated: 8/09/2009
This lab is a completely revised version of Lab 8 in the manual. You should read the theory section of Lab 8, but all of the procedures and data sheet are on a handout. We will still use the post-lab questions, since the objective of the lab is unchanged. In addition, doing pre-lab question 5 will remind you what the computer is doing for you this week.
Prelab
Read the handout carefully so you will have an idea of how to use the Data Studio software to make this measurement instead of having to do the labor by hand as we did in Lab 1.
Answer all 6 questions from the prelab for Laboratory 8 starting on page 89. Note that question 6 requires that you do a linear least-squares fit to the velocity results you obtain from the practice data in question 5. Be sure you allow time to do this fit using Graphical Analysis on a computer in the open-access lab. Attach a graph of your fit to the prelab.
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A major revision of this lab is complete. The material below may still need updates. |
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Comments
It works best if you start taking data with Data Studio before you release the glider, and stop it after the mass hits the floor and the glider bounces back from the end of the track. The information you need to do this is similar to the info given about using the Data Studio program in Lab 7.
Note that you will make 5 measurements in this lab with the Data Studio program, recording them on the data sheet provided with the lab handout, and then do a linear least squares fit to the acceleration data with Graphical Analysis. This last step and the final analysis follows the lab manual, but the analysis of the raw data to get velocity curves and accelerations is completely different from the method shown in the lab manual.
A balance is supplied so you can measure the masses used to accelerate the puck. Experience shows that these masses can vary a small amount from their nominal value, and you will get more consistent results if you always measure the ones you use for a given run.
You also need to remember the comments from the last lab about the order of data in your calculation tables often being in exactly the wrong order for entry into Graphical Analysis. You enter the independent variable (t) first, not the dependent variable, v, regardless of how they appear in the data or calculation tables.
Apparatus
The blower should be plugged into the wall outlet, while
the computer and the analog-digital converter should be plugged
into the power bar on the front side of the lab table.
Details
Motion Detector:
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The initial setup by the laboratory staff should have placed the
motion detector on the analog-digital converter
next to the computer for safe storage (click link for a photo),
but you should find it ready to be used,
attached to the end of the air track with a rubber band.
If it does not appear to be attached properly, contact the lab instructor. The motion detector is expensive and has a very fragile transmitter. Please be very careful to avoid damaging it. |
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The motion detector must be aligned with the conical reflector on
the glider.
The motion detector has a minimum range of about 15 cm, so we will never make measurements with it as close as you see here. We will set it up so it starts about 1/3 of the way down the track. The calibration distance is from the detector to the point of the conical reflector. IMPORTANT: Do not touch the thin film on the front of the detector. It is very fragile. Measurements can be made from the side or top, aligning the meter stick by eye. |
Extra Masses:
A key part of this lab is keeping the total mass of the system
(m + M) constant while varying the mass "m" that provides the
force to accelerate the system. The trick to doing this is to
send the unused small masses along as passengers on the glider.
Using Data Studio to collect the data
The details on how to use the Data Studio software to collect the data and determine the acceleration from the graph of velocity -vs- time is on the lab handout, but some of it is similar to the information given about using the Data Studio program in Lab 7.
Contact me
if you have any questions.
