Sunday, October 16, 2011

Science Sunday – Heat and insulators


Science Sunday

We did two science experiments this week, both related to heat.

{I find many good ideas for preschool and early elementary science activities over at Kids Science Experiments.  There are a lot to choose from, and most are very easy to prepare for.}


First Experiment – Magic Jumping Coin

To do this you need a glass bottle, icy water, and a quarter.

Place the bottle neck and the quarter in the icy water for about a minute:bottle in icy water

Take them out and place the quarter over the bottle opening.  Place your warm hands around the bottle neck:watching the coin "jump"

After a few seconds the coin will “jump” (more of a small “pop” up and back down).  Why?  The molecules in warm air move around more and take up more space than the molecules in cold air.  When your hands warm up the air in the cold bottle, the molecules start moving around more and to make room, they “pop” the coin off the top of the bottle. 


Second Experiment – Insulators

***Note!***  Karen from Science Matters (click on the link to check out her awesome blog) emailed me with some good information about the experiment below.   Apparently we did it all wrong, and that is proof that learning is a lifetime sort of thing, right? ;)  Here’s some good information and ideas that she gave me:

“To truly test the insulating properties of the materials, you'd want to wrap the sides of the glass (around where the water is) in the material.  You actually lose more heat through the sides of the glass than the top.  It's not surprising that the temperatures were very similar, since all 4 water samples were losing heat through the glass at about the same rate. 

It's surprising that the aluminum foil insulated as well as it did - aluminum is a conductor, basically the opposite of an insulator - it carries heat away.  Think of stirring a big pot of soup... if you used a metal spoon, what would happen after the spoon was in the pot for awhile?  It would get hot - too hot to tough eventually.  It's carrying the heat away from the soup (and to your hand).  A pot holder or an oven mitt is a great insulator - if you put that around the spoon, it will be insulated and the heat won't reach your hand (or it will take a very long time to do so). 

Wool is a great natural insulator - it's job, on the animal, is to keep that animal warm by trapping its body heat.  Cotton does pretty well, when it's dry.  The problem with cotton, is that when it gets wet (either from sweat or from precipitation) is that it traps the water, which kills its insulating properties.  (That would be a great experiment - comparing a dry cotton cloth with a wet one).

If you ever decide to re-try the experiment, some other fun materials to test: a pot holder, bubble wrap.  Of you could try several different mittens/gloves and see which would do the best job at keeping your hands warm!”

We gathered up our materials: 4 glasses, 4 rubber bands, a fluffy sock, newspaper, aluminum foil, and a cotton cloth:insulators and glassesM and I both guessed about which of these materials would keep hot water warm for the longest amount of time.  I guessed the aluminum foil, M guessed the cotton cloth.

We heated some water in the microwave, and filled each glass to about 2 inches below the top.

Then we quickly placed our insulating materials over the glasses, and held them in place with rubber bands:covering the glasses of warm water

We set the timer for 30 minutes, then checked the glasses:checking the glasses

Each one still felt pretty warm, so we got out our candy thermometer and took their temperatures:taking the temp of the water

The glass that was covered with the cotton cloth had the warmest water.  The aluminum foil glass had the second warmest.  The sock glass was in third place, and the newspaper glass was the coolest.

We were supposed to use a woolen sock, but I could not find one (I know my husband has some that are real wool, but they are stored away right now).  I’m guessing the wool would be the best insulator, and so I guess it makes sense that cotton came in first with our experiment, although I was surprised at first. 

  science exp. insulators (3)   

To make the experiment as accurate as possible, we should have had 4 candy thermometers and placed them in the glasses all at the same time.  However, the cotton-covered glass was the third one we tested, and it was still warmest, so I suspect our results were correct.

Check out the Science Sunday link-up to find more fun science activities!

Have a beautiful day! :)

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