Experiment
Fat against freezing
You need:
- A tray of ice cubes.
- A bucket, half full of cold water.
- Two rubber gloves (washing-up gloves or disposable gloves, but they must be tight).
- 1-2 dl cooking oil.
This is what you do:
Put the ice cubes in the bucket.
Wait a few minutes so that the water has time to get really cold. Fill one glove with oil, enough so that the hand is completely covered in oil when you put it on.
Take the empty glove on the other hand.
Put both hands into the ice water.
Observe:
Do you know the difference?
Which animal needs fat under the skin in winter?
Explore further:
Try the same experiment with other fabrics such as woolen socks or cotton balls instead of oil. Which material insulates best against cold?
What is going on?
Animals that live in the water, such as seals and whales, have a thick layer of fat (fat) under their skin. The layer of fat helps them keep warm in the cold sea! The fat layer is an insulator.
Insulator is another name for a material that is a poor conductor of heat. Insulators reduce the transfer of heat from an object or place that is warm (like your hand) to an object or place that is cooler. Heat always moves from hot areas to cold areas in an attempt to equalize the temperature between the two places. Insulation is used to keep hot things warm and cold things cold.
Animals have a number of different mechanisms to keep warm. Lard and fur keep arctic animals warm. Down feathers trap a layer of air next to the body to keep birds warm.
Materials that insulate to keep the heat in or the cold out are very important in everyday life to keep us healthy and comfortable. A thermos keeps milk cold and fresh so that it is still safe to drink at lunch. Slippers with fleece keep your toes cozy and warm when the floor is cool in winter.
