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# Blubber Hand

Fat hands are better than frozen hands. Try your hand at this icy experience.

• Science > Chemical sciences > Year 4 > ACSSU074
• Science > Biological sciences > Year 5 > ACSSU043
• Science > Physical sciences > Year 9 > ACSSU182

## You'll need

• large mixing bowl (or similar container)
• cold water
• ice
• 2 zip-lock bags
• soft margarine or lard
• spoon
• thermometer (optional)

## Try this

1. Fill the bowl with water and ice to make icy-cold water.
2. Use the spoon to fill one of the zip-lock bags with soft margarine or lard.
3. Put a clean zip-lock bag into the full bag to sandwich the margarine or lard between the two bags.
4. Put your right hand in the double bagged margarine and your left hand in the remaining empty zip-lock bag. If you can, have a friend seal the zip lock bags around the wrists.
5. Place both hands in the icy water, being careful to keep the openings of the zip-lock bags above the water to prevent water from entering the bags.
6. Keep your hands in the water for about 1 minute or until your hands feel uncomfortable. Which hand feels colder?

## Further investigation

• If this is done as a classroom activity, keep a tally of the number of students who felt their left hand was colder, felt their right hand was colder or couldn’t tell the difference. Discuss the class’ results.
• Time how long people can last with their hand in the ice cold water.  Do people last longer with their right or left hands? Can men or women keep their hand in the ice water longer? Collate the results and present them in an appropriate way to explore the maths in this activity.
• If you do pose this challenge, make sure you set an upper limit for how long students should leave their hand in ice water. Mythbusters set a limit of three minutes when they tried the experiment, but you might want to go even shorter than this!
• Try other materials (e.g. cotton wool, tissues, vegetable oil, etc.) in zip-lock bags to determine if they are better or worse insulators than margarine or lard. Is there a way you can classify this in a quantitative way, along with the qualitative “feeling” test?

## What's happening?

In most cases, the left hand should feel colder than the right hand. Heat transfers from warmer objects to cooler objects. A human’s body temperature is 37°C and the temperature of the icy water is close to 0°C. The heat from the left hand transfers into the cold water. An insulator slows down the transfer of heat. The right hand feels warmer because the margarine or lard acts as an insulator to slow down the transfer of heat from the right hand to the cold water.

In this activity, the zip-lock bag represents the skin of a whale and the margarine or lard represents the blubber of a whale. Whales are mammals and all mammals are endothermic, which means they produce body heat through metabolism. Whales maintain their body temperature at close to 37°C by controlling their rate of metabolic heat production.

Whales live in a marine environment, which is colder than their body temperature. Amazingly, some whales live part of the year in the near-freezing Arctic or Antarctic waters. Whales are capable of surviving in cold ocean waters because they have many adaptations that help to reduce heat loss to keep their bodies warm. For example, they have a thick layer of fat, called blubber, just beneath their skin. The blubber acts as an insulator to slow down the transfer of heat from their warm bodies to the cold ocean water.