Title: One Hot Puppy

Purpose:

To measure the temperature and pressure changes in a closed car. (Let's learn how to set-up and use the TI-82 with the CBL)

Materials:

• CBL
• TI-82 calculator
• Barometer probe or pressure sensor
• CBL-DIN adapter
• Temperature probe
• TI-Graph Link
• Graphical Analysis

Overview:

Students will monitor the pressure and temperature changes in a closed vehicle for one hour. The students will learn how to operate and link the TI-82 to the CBL. The students will also calibrate the pressure sensor (or barometer). The data will be downloaded using the TI-82 Graph-Link. Students will save data to a disk and transfer the data to their report.

Calibration of Barometer

• Obtain current barometric pressure reading (airport or barometer).
• Follow instructions on the CBL for the first reading. The first reference will be for the current barometric pressure. Be sure to isolate the probe from any air movement.
• The second reference will be made using the syringe and tubing from the pressure sensor. If not present already, place a short piece of tubing on the barometer. Attach the syringe with its plunger depressed to the tubing. Extend the plunger to the 20 cc mark and press CH VIEW on the CBL. Complete calibration as instructed by the TI-82 calculator.
• The program will give you the following variables:
  (K0,B) and (K1,A).
  Write down these variables. Each time you start the program you need to calibrate the probe and these values may save you time. You can manually enter these values later.

Procedure:

1. Connect the CBL to the TI-82 calculator and turn both of them on.
2. >Attach the probes to the CBL. The barometer should be in CH1 and you will need to attach the CBL-DIN adapter. The temperature probe should be in CH2. Manually enter the intercept (K0,B) and the slope (K1,A).
3. Select the PHYSICS program from the menu. Select "SET UP PROBES" You will use two probes in this exercise. Calibrate the pressure sensors using the calibration directions or manually enter the intercept (K0,B) and the slope (K1,A) as given by the teacher.
4. Now you are ready to collect data. First monitor your data to make sure your probes are reading correctly. One likely problem is not calibrating the pressure sensor correctly. Press (+) when finished.
5. Record.
   • The location of the vehicle.
   • The geographical direction of the front of the car (N, NE, S, SW, etc.)
   • Objects that may cast shadows over the vehicle during the time interval
   • Types of clouds present
   • Percent cloud cover
   • Date and time.
6. You will monitor the pressure and temperature changes in the closed vehicle for one hour. Select COLLECT DATA again and this time you will choose (2) TIME GRAPH. You need to decide on a proper sampling rate. The TI-82 can collect up to 99 data points while the CBL can collect up to 512 points. You need to decide on the time between samples and the number of samples you will collect during the time period. (Do you really want or need 500 data points?) The TI-82 will display the total time that samples will be collected. When you are ready to begin your experiment, press (1) USE TIME SET-UP. The CBL will begin sampling data once you press enter. Close the doors to the vehicle and wait one hour.

7. When you return to your apparatus the CBL should read done. Follow the instructions on the calculator to view your data. Return to the classroom without turning off your apparatus.

Downloading Your Data to Graphical Analysis (GA)

• Quit the program on the TI-82 once you have downloaded the data from the CBL. Your data should be in the lists.

• Open a new file in GA and add one column to the data table.

• Connect the calculator to the link. Press 2^nd LINK. You will SEND data. Select (2) SELECT ALL-. Select lists one, two and three.

• Select IMPORT DATA FROM TI-82 from the FILE menu and press transmit on the calculator. Pronto - you have data!

• Save the data to your disk.

To The Tech Center

• Open GA (Login Science, Windows) and open your file.

• Create a Pressure vs. Temperature graph.

• Cut and paste your data and graphs into your Excel. Now you can write your lab report in MS Word and paste your file into the report.

Questions:

1. Describe the Pressure vs. Time and Temperature vs. Time graphs.

2. Describe the relationship between pressure and temperature in this experiment.

3. According to your results, how long could the puppy remain in the car before becoming uncomfortable? When would the puppy enter the danger zone? How did you determine this?

4. If you absolutely had to leave your animal in your car, what would you do to make sure it was safe from overheating?

Further Investigations

• Pressure and temperature changes of a gas in an exploding balloon.

• Pressure and temperature changes in a vacuum when boiling water at low pressure.

• Atmospheric pressure changes as a storm front approaches.

• Atmospheric pressure changes during the day.

• Pressure changes with changes in elevation.

• Pressure changes during an elevator ride.

• Pressure changes through a tunnel.

• Pressure changes in a speeding car.

Sample Data from a Thirty Minute Time Period

Toyota Truck parked under trees.

Front of truck facing east with probe located on front seat.

July 24, 1997 from 9:45 AM to 10:15 AM in Palo Alto, CA.

Cirrocumulus clouds with 10% coverage.