Purpose
To demonstrate whether fans are effective means to cool body temperature.
Additional information
Imagine the middle of summer where sweltering heat is causing you to burn up like you're sitting dead-center in a 400 degree oven. Your body temperature is rising and the sweat is beginning to drip from your brow. Without the aid of an air conditioning unit, your only refuge is that of a large fan placed several feet from your body. As the fan slowly rotates towards you, a comfortable gust of air is projected your way, refreshing and cooling your body, even if only for a moment. As each rotation passes, your body feels cooler and cooler. The fan is your savior on a brutally hot day as it keeps your skin cool and helps you to beat the heat.
The question is... does the fan REALLY cool your body? When that gust of wind is projected towards you, it's essentially projecting heated air. This experiment will explore whether fans are viable sources to cool our bodies on a hot summer day or whether their effectiveness is just a state of mind.
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Required materials
- Two identical pans (such as pie pans or baking pans of the same size)
- Two thermometers
- Clock or timer
- Ruler
- Measuring cylinder (even a turkey baster will do the trick)
- Large electric fan
- Water
- Pen or pencil
- Journal to record your results
Estimated Experiment Time
One or more days (could take several depending on your environment)
Step-By-Step Procedure
- 1. Place your fan on a flat, stable surface where it can remain undistributed for several days.
- 2. Place the first pan approximately 14 inches from the fan in direct proximity of the fan current.
- 3. Place the second pan in the same room, but outside the direct current of the fan (the fan should not blow air towards the second pan).
- 4. Use your measuring cylinder to add 1 ounce (30 milliliters) of warm water to each of the two pans.
- 5. Place a thermometer in each of the two pans. Wait a few moments and then record the starting temperatures in your journal. Keep the thermometers in the pans.
- 6. Turn the fan on and place on a medium speed setting. Leave the fan running undisturbed.
- 7. After 20 minutes have passed, check on your pans of water. Note any changes to the water levels in your journal, as well as temperatures.
- 8. Check on the pans every 20 minutes, noting the water levels and the water temperatures.
- 9. After a few hours the pan with the water in the direct path of the fan current should be evaporated. The pan left outside the path of the current will still contain water. The second pan may take 24 hours or more before the water fully evaporates. When the water does finally evaporate, record the results in your journal.
Note
The environmental conditions of the room where the experiment takes place will have an effect on the overall time it takes for evaporation to occur. Make sure you conduct this experiment in a clean environment where the pans can remain undisturbed! Also make sure you check the water temperatures and levels on a consistent interval for the most accurate results.
Observation
What seems to take place after the first interval? How about the second? At what point did you notice a significant drop in the level of water? How long do you think the water would take to evaporate if you used a VERY large fan? How about if you cranked the speed up to high? What about on low?
Result
The outer layer of skin excretes sweat and oil for the purpose of maintaining our body temperature. As temperatures rise, we sweat. Our body heat, however, is not reduced when we sweat. Instead the sweat evaporates on the skin resulting in a cooling effect. Fans project a stream of air that sweeps away the humid layer and replaces it with a dryer and cooler layer that is similar to, but more effective than, natural evaporation. The pan with the water directly in front of the fan evaporates at a rate much higher than that of the pan outside the fan current stream, proving that the fans remove moisture at an accelerated rate. Fans, much like our own sweat, do not reduce or temperature but they help us regulate it.
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