What it does
This experiment shows how sweating helps keep
your body cool.
What you need
-An outdoor thermometer
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
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.