In last weeks experiment lots of students enjoyed playing with the icy water and seeing how long they could keep their hands in the water. This lead to us wondering how polar bears survive in the arctic waters.
There are a few important factors (fur type, skin colour) but the main reason is polar bears have a 4 inch layer of fat under their skin. Soo all we had to do was make up a layer of fat to cover our hands with and we were set.
The next question was where to get the fat? And that's where the butter came in. We got some cream and put it in a jar with a marble. We then proceeded to shake it as hard as we could, taking turns when we got tired. After about 7 minutes the cream started changing. We knew it was ready when we could see some very thin milk at the bottom and in the middle of the jar - butter!
We then had to try it to see if it was really butter.
Once we had the fat we put a back full of fat in a container full of icy water to see if it made a difference. And it did!
How it works:
As the cream is shaken, the fat molecules get out of position and clump together, eventually clumping so much that butter forms. You can tell this because the fat molecules have clearly separated from the liquid in the cream.
This experiment idea came from one of our students in science club. Neave had read in one of her science books at home about an egg being sucked into a bottle. We first tried it the traditional way of lighting some candles in a glass bottle and then placing a boiled egg on the top. The egg was slowly sucked into the bottle neck but got stuck halfway.
We then tried it a different way. We stuck three candles into the egg and then lowered the bottle over the egg. Quick as a flash the egg got sucked all the way into the bottle!
No photos of this experiment as we got too excited doing it.
To help us understand more about air pressure we also did another experiment. We had some trays full of icy water. We then placed an empty bottle on top that had just been full of hot water.
After the bottle had been in the water for a short while we observed that it was starting to crack and constrict.