Have you ever wondered why it’s so hard to get ketchup flowing out of a bottle, or why no-drip paint doesn’t drip?
Ketchup, no drip paint, liquid soaps and shampoos are all part of a really amazing category of fluids known as “shearing liquids.” These fluids are pretty thick when they’re sitting still, but they get thinner or more “liquidy” as they flow, because movement decreases their viscosity, or thickness, making them more slippery.
Back in 1963, an engineer named Arthur Kaye noticed streams of liquid shooting from the surface below a stream of shearing liquid he was working with. This strange, short-lived phenomena became known as the Kaye effect.
With a chair, tape, some dish soap and a plastic ziplock bag, you can do your own Kaye effect experiment at home and watch soap jets shoot like ski jumpers from the very slippery shearing liquid soap pile below
-Tape a plastic ziplock bag to a chair with one corner or the bag pointed toward a plate underneath. The bag corner nearest the floor should be around 20 cm (about a foot) from the floor.
-Fill the bag with liquid soap or dish detergent. We added a few drops of food coloring to ours.
-Cut off the corner of the bag closest to the floor with scissors to make a tiny hole for the soap to flow through (1mm.) You may have to make it a little bigger, but you want a very thin, steady stream of soap flowing to the plate.
-Watch for jumping streams of soap. If it’s not working, try changing soap and adjusting bag hole size and bag height! What happens if you put the plate below at an angle?
To learn more about the Kaye effect and other cool physics stuff, visit Dr. Skyskulls’ website. He’s the physicist who told me about this experiment and helped me work out the protocol.
If you’ve done an experiment where you drip water onto a penny, or made Tie Dye Milk, you know what surface tension looks like here on Earth. How does it look in space?
Here’s an amazing video demonstrating how the surface tension of water looks in zero gravity on the international space station. Fascinating!
Plants are wonderful chemical reorganizers. Using the sun’s energy and a process called photosynthesis, they can turn water and carbon dioxide into sugar (glucose) and oxygen.
Thanks to plants and other autotrophs like algae, Earth has an oxygen-containing atmosphere that can sustain animal and human life.
To watch plants make oxygen, all you need is a water plant like Elodea (available at pet stores), a large container, water and a few small clear glasses or test tubes.
Fill the large container with water and turn your small, clear containers on their sides underwater to remove all the air bubbles.
Cut a branch off of your plant, place it under water in the large container, shake off any air and put it under your small, clear container- stem side up. Invert the small container, allowing no air to enter it. Repeat the experiment with your other small clear container, but don’t add a plant. This is your control. If you’re using test tubes, you can put them in small cups or beakers so they don’t tip over. (See photo above.)
Place your experiment in bright sunlight or near a strong lamp and observe what happens. You should see oxygen bubbles form on the plant as it performs photosynthesis. In a test tube, you will eventually see some water displaced by oxygen.
What happens if you duplicate the experiment in a room with no light?
Tap water contains some carbon dioxide. How do you think the experiment would work with lake or pond water?
Here’s the video we made last weekend for KidScience app that shows you how to stand on a carton of raw eggs without breaking them:
Remember, Force is pressure per unit of area. In the video, you’ll see what happens when you try to stand on eggs in high heels and the force isn’t evenly distributed.
One of the first things you learn when you do science is that experiments don’t always turn out the way you hope they will. And that’s OK. If at first you don’t succeed….
We tried to measure how far a sneeze would throw visible droplets by putting grape juice in our mouths and tickling our noses with feathers dipped in pepper. Sadly, no matter how hard we tried, we couldn’t seem to sneeze with grape juice in our mouths. Laughing so hard we spit the juice out was one unexpected outcome. We decided to try it again in the future using petri dishes spaced at intervals to avoid the grape juice problem.
Since there was no school today and it was ten degrees below zero (F), we tried throwing boiling water into the air to see if it would freeze before it hit the ground. Once again, our experimental conditions were less than perfect, and although some of the water froze into an icy cloud, the majority hit the ground with a splash. The experiment would have worked better at -20F, but it was still fun!
Salt lowers the melting/freezing temperature of ice, which is the solid form of water. Here’s a fun experiment you can do to see for yourself how Sodium Chloride (table salt) makes ice melt and water refreeze on a string, allowing you to “magically” lift an ice cube from a glass of water.
Click here for detailed instructions and more about the science.
This video will soon appear on KidScience app‘s Premium version, which allows you to easily search for experiments and videos based on kids’ ages, type of science, what you have on hand, or how much time you have.
Ever wonder how much starch is in your Thanksgiving dinner? Click here for a fun experiment that lets you test your favorite foods for starch using iodine from the medicine cabinet.
Remember to supervise small children if you do this experiment, since iodine should not be ingested! Happy Thanksgiving!
It’s not quite hot enough to fry an egg on the sidewalk, but a hot summer day like today would be perfect for making a solar oven from a pizza box! (This is a repost of one of our summer favorites.)
When my friend Sheila, who works at NREL (the National Renewable Energy Laboratory) sent me this project, I couldn’t wait to try it out. We first tried it out on a cool spring day in Minnesota and to my surprise, it worked. The oven didn’t get very hot, but we were able to warm a chocolate chip cookie enough to make it soft and melt the chips.
NREL suggests using your oven to make s’mores, which we’ve tried and is really fun. (We did it on Kare11 last summer.) The solar oven is surprisingly easy to make. It only took us 10 or 15 minutes..
You will need: 1 pizza box from a local pizza delivery store (Little Caesars, Domino’s, Pizza Hut, etc.), newspapers, tape, scissors, black construction paper, clear plastic wrap, aluminum foil and a dowel or stick to prop the lid up. You will also want to have some food to warm in your oven-marshmallows, chocolate, etc.
Make sure the cardboard is folded into its box shape. Carefully cut out 3 sides of a square in the lid of the box. Do not cut out the fourth side of the square, which is the one closest to where the pizza box lid hinges. Gently fold the flap back along the uncut edge to form a crease. See photo below!
Now, Wrap the underside (inside) face of the flap that you made with aluminum foil. Tape it so that the foil is help firmly but so that there’s not too much tape showing on the foil side of the flap.
Open the box and place a piece of black construction paper so that it fits the bottom of the box. Tape it by the edges. (We used two pieces.)
Roll up some newspaper and fit it around the inside edges of the box. This is the insulation. It should be about 1-1 ½” thick. Use tape (or other materials you can think of) to hold the newspaper in place. Tape it to the bottom of the box so that you can close the lid. (We taped it to the sides and had to cut the tape so that we could close the lid. Luckily our newspaper fit in tightly enough that we didn’t really even need the tape.)
Finally, cut plastic wrap an inch larger than the lid opening on the box top. Tape it on the underside of the lid opening. Add another piece of plastic wrap to the top of the lid opening. This creates a layer of air as insulation that keeps heat in the box. It also makes a window you can look through at the food you’re “cooking.” BE SURE THE PLASTIC WRAP IS TIGHT.
You are almost done! According to NREL, the oven needs to sit at an angle facing the sun directly so you’ll need to make a prop. You could probably just use a book or something under the hinged side of the oven. However, I missed this when I read the directions and we just put it flat on the ground. The flap of the box top needs to be propped open—a dowel or ruler works great. We used a wooden skewer that I broke the sharp point off of. This way you can change the amount of sunlight striking the oven window. Play with the angle of the flap to see how much sunlight you can get to reflect on the food.
Check every once in a while to see how well your food is being heated by solar thermal energy. If you’re is interested in finding out how the sun cooked your food, go to http://www.nrel.gov/ NREL’s website has great information on solar energy and many other sources of renewable energy.
Would you be surprised if I told you that you could stand on a carton of raw eggs barefoot without breaking them? Or that you can squeeze an egg with all your might without even cracking it (provided there are no cracks in the egg and you’re not wearing a ring?)Here’s a video of us doing these eggsperiments on Kare 11 Sunrise news!
Chicken eggs have delicate enough shells that chicks can peck their way out, but their architecture is nothing short of amazing. Their arched shape makes them able to handle large amounts of pressure without cracking, which is extremely important, since hens must sit on them in order to hatch them out. Humans use arches too, for designing strong building and bridges.
Remove any rings you’re wearing, place a raw egg in a plastic baggie and wrap your hand around it evenly. Squeeze as hard as you can. Did you break it?
Remove your socks and hold on to a chair or someone’s hand. Carefully step onto the eggs with your entire foot. Remember: pressure is force per unit of area. The idea is to equally distribute your weight, and therefore the pressure, across all twelve eggs. Let go of the chair.
Did it work? How important do you think it is to keep your foot flat? What would happen if you tried the same experiment in pointy high-heels?
Remember to wash your hands after touching raw eggs so you don’t spread Salmonella bacteria around!