Evaluation copy. Wind Chill. computer OBJECTIVES MATERIALS

Transcription

1 Wind Chill Computer 28 A nice breeze can cool you down on a hot day or send a chill through you on a day that is already cold. Wind carries heat away from our bodies making us feel cooler. This phenomenon is called wind chill. The wind chill temperature (sometimes called the wind chill factor) is the temperature we feel based on both the actual temperature and the wind speed. In this experiment, the effect of wind on the temperature of a warm body will be measured and analyzed. A Temperature Probe will measure the temperature of warm water in a flask that represents a human body. A second Temperature Probe will measure the actual temperature of the air. There will be no wind in Part I, whereas wind will be generated by a fan in Part II. OBJECTIVES In this experiment, you will Use a Temperature Probe to measure the effect of wind on the temperature of a warm body. Use a Temperature Probe to measure the effect of wind on the temperature of the air. Interpret your results. MATERIALS computer ring stand with clamp Vernier computer interface rubber stopper Logger Pro 125 ml Erlenmeyer flask 2 Temperature Probes warm tap water fan Evaluation copy Figure 1 Earth Science with Vernier 28-1

2 Computer 28 PROCEDURE Part I No Wind 1. Connect the two Temperature Probes to the Vernier computer interface. 2. Carefully slide a rubber stopper onto Probe 1 and insert it into the Erlenmeyer flask. 3. Clamp Probe 2 onto the ring stand so that the tip of Probe 2 is at the same height as the tip of Probe 1 as shown in Figure Prepare the computer for data collection by opening the file 28 Wind Chill from the Earth Science with Vernier folder. 5. Remove the rubber stopper and probe from the flask. Add around 125 ml of hot tap water. Replace the rubber stopper and probe. 6. Monitor the temperature of Probe 1 on the computer screen. It will rise at first but then start to drop. When the temperature of Probe 1 starts to drop, click to begin data collection. 7. Keep the air as still as possible during this first No Wind run. Data collection will stop after 5 minutes. 8. Store this data by selecting Store Latest Run from the Experiment menu. Part II With Wind 9. Position the fan somewhere within a meter of your setup. Turn it on and adjust it so that it is blowing steadily at your ring stand. It should not be oscillating. Turn the fan off. 10. Empty the Erlenmeyer flask and refill it with fresh hot water. Try to get water close to the same temperature as in Part I. 11. Reposition the temperature probes as shown in Figure Monitor the temperature of Probe 1 on the computer screen. When the temperature begins to drop, turn on the fan, then click. Monitor the temperature for 5 minutes. 13. Determine the minimum and maximum temperatures for the two probes in each run. a. Click the Statistics button,, then click to display the statistics. Note: You may need to move the Statistics boxes around to see which box is pointing to which run. b. Record the minimum and maximum temperatures for both temperature probes and both runs in your data table. 14. Print copies of the graph as directed by your teacher Earth Science with Vernier

3 Wind Chill DATA Part I No Wind Probe 1 Flask Probe 2 Air Part II With Wind Probe 1 Flask Probe 2 Air Maximum temperature ( C) Minimum temperature ( C) Temperature change ( C) PROCESSING THE DATA 1. In the space provided in your data table, subtract to determine the temperature changes. 2. According to your data, does wind cool the actual temperature of the air? Explain. 3. According to your data, will a warm body (represented by the warm water in the flask) cool faster when the wind is blowing or when the air is still? Explain. 4. If wind does not make the air temperature colder, why does it make a person feel colder? Earth Science with Vernier 28-3

4 Computer Wind chill depends on both the air temperature and the wind speed. A chart has been developed that estimates the wind chill for humans (see chart below). To use this chart, find the air temperature across the top of the chart, then find the wind speed down the side. The resulting number in the chart is the wind chill temperature. Use the chart below to determine the wind chill when: a. the temperature is 5 C and the wind is blowing at 60 kph. b. the temperature is 5 C and the wind is calm. c. the temperature is 20 C and the wind is blowing at 15 kph. d. the temperature is 0 C and the wind is blowing at 10 kph. Wind Chill Chart Wind Speed (kph) Temperature ( C) Calm EXTENSIONS 1. Test the effect of wind on warm objects of different sizes. 2. Test the effect of different wind speeds on an object s temperature. 3. Research and explain how the Wind Chill Index was developed Earth Science with Vernier

5 Vernier Lab Safety Instructions Disclaimer THIS IS AN EVALUATION COPY OF THE VERNIER STUDENT LAB. This copy does not include: Safety information Essential instructor background information Directions for preparing solutions Important tips for successfully doing these labs The complete Earth Science with Vernier lab manual includes 33 labs, 6 projects, and essential teacher information. The full lab book is available for purchase at: Vernier Software & Technology S.W. Millikan Way Beaverton, OR Toll Free (888) (503) FAX (503) info@vernier.com