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Experiment

What it does
This experiment shows how sweating helps keep your body cool.
What you need
-An outdoor thermometer
-Cottonball
-Rubbing alcohol
Watch
What to do
     1.  Put the thermometer on your or work surface for about 5 minutes so that it will register at room temperature. Observe this temperature.
     2.  Wet the cottonball with alcohol
     3.  Spread a thin layer of the wet cotton across the bottom bulb of the thermometer.
     4.  Blow lightly on the wet cotton for about 30 seconds. Watch what       happens to the temperature reading.
What it's all about
The temperature goes down as you blow on the wet cotton, because the alcohol on the cotton is evaporating. Evaporation occurs when a liquid absorbes enough heat energy to change into a gass. In this experiment, the alcohol takes heat enegry from the mercury in the thermomoter. This causes the mercury to contract and move down the thermometer, giving a lower temperature reading.
When it's hot outside your body relesaea liquid from youre skin. As the liquid (sweat) evaporates, it removes heat from youre skin and makes you feel cooler.