Investigating the effect of size and covering on rate of cooling

Introduction:
How does the skin react when it’s too warm?
If your blood temperature rises above 37 degrees, the hypothalamus sends messages which cause a different set of responses by your skin.  The hairs lay flat on your skin because the erector muscles relax, and because of that, there is no longer any air trapped and allowing heat to be lost by radiation. The capillaries dilate, bringing more blood to the surface where it can lose heat.  (This is also the cause of the red glow on the skin of a person whose blood temperature is above 37 degrees) Sweat starts to emerge from sweat glands. This is a fluid made from blood plasma, containing mostly water, some salts and urea.  The sweat evaporates and cools the skin. This is a very important process, because it is the only way we can lower our body temperature.
Research question:
The goal of this experiment is to find out if the size and surrounding of a test tube has any effect on the rate of cooling.
The research question will be: Does the size and surrounding of a test tube have any effect on the rate of cooling?
Hypothesis:
My predictions are that the size and surrounding indeed affect the rate of cooling. As described in the theory above, our body tries to adapt our surroundings  in order to lower our body temperature. If we wrap the test tube in cotton, my expectations are that it will cool more slowly, because as described above, the capillaries expand in order to be closer to the skin and lose heat to lower the temperature.  If we leave the test tubes to cool without any cotton wrapped around them, my expectationis that those test tubes will cool the quickest, because the heat will be able to evaporate more quickly than when there’s another layer of cotton wrapped around the tube. 
I also expect the smaller test tube to cool the fastest, because it contains water that is less hot, allowing it to cool down quicker. You can compare this with hot soup. If you eat it from a bowl, the soup in the corner is way cooler than the soup in the middle, because there’s more soupin the middle, so it cools down less quickly. However, the soup in the corner will cool down faster because there is less soup,and therefore, less heat.

Method/Procedure:
Materials:
•    2 large test tubes
•    1 small test tube
•    1 water bath
•    1 test tube rack (small test tubes)
•    1 test tube rack (large test tubes)
•    3 thermometers
•    1 large piece of cotton
•    1 thick rubber band
•    1 stopwatch
•    Graphic paper
•    1 tissue
Procedure:
First of all, a results table was drawn. Secondly, we had cleaned one of the large test tubes (so there would not be any water on the outside of the tube), wrapped it in cotton and secured the cotton with a rubber band. Then we named the different test tubes:
•    The large test tube wrapped in cotton was named A
•    The other large test tube which wasn’t wrapped is cotton was named B
•    The small test tube was named C
We had put the test tubes in a water bath until they had all reachedapproximately the same temperature.Next, we measured and notedthe temperature. Then we had put small pieces of cotton in the top of the test tube to imitate cork. After that we had measured the temperature every 2 minutes for 10 minutes. Finally, we had plotted a graph with time on the horizontal axis and temperature on the vertical axis, with a separate line for each test tube.






Nina Wieland| T3A
22 -11 -2011