Thermodynamics: Polar Bears, Whales and Penguins
There are some big concepts in this homeschool physics lab, but we break them down into something that the kids can see and feel. Don’t be daunted by thermodynamics, in this lab the kids get up-close-and-personal with heat, cold, and how temperature transfers. It’s a fun lab, and easy to do with a group of kids.
A pair of mittens or socks to protect hands
2 sheets of tinfoil per student or small group
2 large Styrofoam cups per student or small group
2 water bottles prefilled, one with ice water and one with hot water
Laptop (and TV if showing to a group)
Cups of water
Styrofoam packing peanuts
Eco-foam (starch) packing peanuts
1 sandwich baggie pre-filled with about ½ cup of shortening per student
1 empty sandwich baggie per student
A large container filled with very cold (icy) water. Large enough for kids to put a hand in without spilling the water.
For the Demo
Foil pie plate
Acetone – from your local hardware store
ASK who has ever been to a really cold place, with snow or ice. Have they ever been outside there? What happens? (They get cold.) What do they do to stop from getting cold? (They put on winter clothes).
SAY that today you’re going to learn about thermodynamics and polar bears. Seem like an interesting combination?
ASK who knows what thermodynamics means. Write it on the board. THERMO (is from the Greek word thermos meaning heat) and DYNAMICS (change). So, THERMODYNAMICS is the field of physics that relates to heat and energy and how they change. Thermodynamics is a something we’re going to learn about in our homeschool physics labs.
What has this got to do with whales and polar bears? We’ll find out in a bit.
Let’s go back to the idea of being out in a snowstorm and wearing cozy clothes to keep us warm. We wear those clothes to INSULATE ourselves.
ASK if anybody else knows of any other examples of insulation? (Houses have insulation to keep the cold out and warmth in, a thermos to keep soup hot, long johns (if they even know what those are). DO NOT MENTION STYROFOAM CUPS and if the kids mention animals and animal fat, brush over it without dwelling on it.
Set up for the experiment. SAY that you’re going to try an experiment with hot and cold and are going to see what materials are the best at insulating.
HAND out the materials.
Lab 1 – Insulators
Show the kids how to make foil mittens with the help of their partner. Basically, the kids place their hand down on a sheet of foil and fold over the top and sides to make an envelope. Kids can crimp the sides to keep it in place. Get ready for some homeschool physics fun!
The kids should mix around the hot and cold bottles of water until they can’t tell which bottle is hot and which is cold.
ASK the kids to touch the side of the bottle with the foil mittens and see if they can tell which bottle is hot, and which is cold.
REPEAT with the socks or mittens, and then with their hands in Styrofoam cups.
ASK which material was the most insulating? Which one protected their hand the most from the hot water? (should be Styrofoam cup, then mitten, then foil).
ASK who knows what Styrofoam is?
Styrofoam is actually a common name for a material called polystyrene, which is a polymer made up of a long chain of molecules.
Currently, about 200 million cubic feet per year of polystyrene “loose fill” (packaging material) is used in the United States, and most of it ends up in landfills. There’s no good or easy way to recycle it, and it doesn’t compost or decompose. Polystyrene doesn’t compress easily, making it a great choice for packing material but it’s a problem when trying to dispose of it. This is a bigger problem than we can tackle in this homeschool physics lab, but it’s good for them to be aware of it.
TELL the kids that a single Styrofoam cup can take more than 500 years to decompose!!! But, you’re going to make one disappear before their very eyes.
DEMO: Take the kids outside or to a well-ventilated area with a Styrofoam cup and the pie tin with about 2 cm of acetone in the bottom. Have the kids sit in a semi-circle around you and place the cup into the acetone and watch!
(We don’t use acetone on landfills because acetone is a volatile and flammable substance, and because the acetone doesn’t actually remove the Styrofoam – it merely dissolves it (physical change – the air bubbles are merely the air being released from the polymer chain) and doesn’t actually remove it.)
GO back inside and tell the kids to put on their goggles, that they’re going to do an experiment of their own with Styrofoam.
ASK who has seen or used packing peanuts before? Explain their use.
Lab 2 – Styrofoam and eco-foam packing peanuts
Hand out one Styrofoam packing peanut per team of kids.
Hand out one small container of water per team of kids.
Instruct the kids to put the Styrofoam peanut into the water.
Observe – what’s happening? Is the water dissolving the peanut? Tell the kids that packing peanut will be around for another 500 years or more.
Hand out one of the eco-foam peanuts per child.
Instruct the kids to put the eco-foam peanut into the water. Observe.
These peanuts are made of a water-soluble starch so they dissolve in water to a harmless and bio-degradable product.
ASK what this all has to do with polar bears, whales, penguins and other cold weather animals??
Show this video https://www.youtube.com/watch?v=TwfKCX_8fbA
Lab 3 – Fat as an insulator
EXPLAIN that no matter if it is a whale or a polar bear, animals have a layer of fat or blubber to protect them.
Now the kids are going to experience the insulating properties of FAT in this next homeschool physics lab.
Hand out a baggie pre-filled with shortening.
Hand out a second, unfilled sandwich baggie.
Ask the kids to put their hand into the empty baggie, then using that baggie like a mitten, put their hand into the bag with the shortening (kids will have a layer of shortening between the baggies, hands are kept free of fat).
Ask parents to go around and tape the bags around the wrist to keep them on and reduce messes.
Ask the kids to squish the fat around their hand.
Ask the kids to put their uncovered hand into the ice water. COLD!!! Don’t let them keep it in for long.
Then ask the kids to put their insulated hand into the ice water. They shouldn’t feel the cold (or at least not quickly).
REMOVE bags and have clean up.
DISCUSS with the kids how the fat acts as an insulator. Review all that they learned in this homeschool physics experiment!
Polar bears, whales and penguins have adapted to live in cold water, and have developed a thick layer of blubber. Blubber is spread evenly over their body, kind of like the shortening in this lab that covered your hands. Adipose, or fat, has low thermal conductivity, it won’t transfer heat very well, so you won’t feel the heat through the blubber/shortening. Humans don’t have blubber, but we’ve invented insulating material like Styrofoam.