Northern Illinois University
Physics 150A
Lab 2
Computer-Based Laboratory (CBL) and Graphing Lab
Objective
Students will become familiar with the hardware, software and operating procedures of the instruments
to be used in the laboratories by going through the sensor stations that are set up throughout the
laboratory. Data acquisition with appropriate technology in collaboration with traditional pencil and
paper graphing and analysis will develop the student's understanding of slope and rate.
Materials
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Computer and interface
Ice bath
Hot water bath
String
Weight with elastic
Stop watch
Flashlights
Ring stand with horizontal bar
Procedure
Lab groups will divide among the available, self-contained stations.
Basic Procedure
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Turn on computer, log on as “student”.
Bring up “Logger Pro”.
Interface connects sensors to computer.
Plug in sensor, start Logger Pro. Logger Pro should detect the sensor.
Part 1: Temperature Probe
General idea: Generate two data tables and graphs and compare and comment on the slopes of
the graphs.
1. Plug the temperature probe into the interface.
2. Logger Pro should display readings from the probe.
3. Place the temperature probe into the ice water and stir briefly.
4. Set up Logger Pro to start collecting data. You should collect 20 data points, one every 8
seconds, for a total of 160 seconds.
a. In the Experiment menu, choose the Data Collection dialogue. The Collection
tab allows you to set the data collection rate and the experiment length.
b. Check the display to see that you have set the probe correctly, but don’t start
collecting data yet.
5. Prepare hot water in another container.
6. Get ready to collect data. You will be switching the temperature probe from the cold
water to the hot water after 5 data points have been collected.
7. When you are ready, select “start” in Logger Pro. You should see data points appearing
on the screen.
8. After 40 seconds, when the 5th dot has appeared, quickly move the temperature probe
from the cold water to the hot water. Data collection will continue.
9. When data collection is complete, you will see the graph of temperature vs. time on the
computer screen.
10. The data you have collected will be displayed in a table in Logger Pro. Copy these data
into a table in your lab notebook.
Discussion:
1. Graph the data from your table according to the guidelines provided in the course
outline.
2. Assess whether or not the graphed data indicated a straight line (direct) relationship
between time and temperature in the region where temperature is changing. If there is
a straight line, calculate the slope.
Part 2: Force Sensor
General idea: Copy the computer graph into your lab notebook and comment on what
happened over time according to your sketch.
1. Plug the Dual Range Force Sensor into the interface.
2. Logger Pro should display readings from the sensor.
3. Connect 40 cm of elastic to the weight; mount it and the Dual Range Force Sensor low
on a ring stand.
4. Set up Logger Pro to take data. You should collect 180 data points, one every 0.02
seconds, for a total of 3.6 seconds.
5. Start collecting data. Pull the weight down and let it go; you can watch the graph form
on the computer screen. Stop the weight when the graph is complete.
6. Sketch the graph in your lab notebook.
Discussion:
1. Explain what happened during the experiment and how the graph supports this
conclusion.
2. What do the horizontal lines represent?
3. Impulse is the change in momentum. Why is there such a large first peak, a dip and then
smaller peaks?
Part 3: Motion Sensor
General Idea: To create a distance versus time graph that is similar to a graph on the board.
1. Plug the Motion Detector into the interface.
2. Set up Logger Pro to start collecting data. You want to collect 60 data points, one every
half second, for a total of 30 seconds.
3. Note that the motion detector will only work for a 0.4 - 6.0 meter range and that side
motion may interfere with detection.
4. Each person in the lab group should select a graph. Sketch a copy of the profile that you
have selected in your lab notebook, leaving room next to it to sketch the profile that you
actually achieve.
5. Try to recreate this graph by moving towards and away the detector.
6. Holding a notebook in front of the person with a sketch of the graph will be helpful.
7. The clicks you hear will now be 0.5 seconds apart. Use this information to estimate how
to duplicate the designated graph.
8. Press start and try to move accordingly. Remember that your starting position is
important.
9. After the 30 seconds, see if your graph looks like the one on the board. Sketch your
graph alongside the graph that you were trying to recreate.
Discussion:
1. Explain the differences, if any, between the graph that you created and the graph that
you were trying to duplicate.
2. What does a horizontal line mean in the distance versus time graph?
3. How would this appear on a velocity versus time graph?
4. What does a steep slope mean compared to a more gradual slope on a distance versus
time graph?
Part 4: Light Probe
General Idea: Sketch the intensity vs. time of a fluorescent light bulb.
1. Plug the Light Probe into the interface.
2. Change the time between samples to 0.001 seconds. Set number of data points to collect
to 99.
3. Point the light probe towards the fluorescent light and sketch the resulting graph.
4. Point the light probe at the flashlight and sketch the graph.
Discussion:
1. How does the intensity of the light from each source change with time?
2. What type of power supplies each light bulb?