Physics and Biology: Dry Ice

Dry ice is unlike the ice we know and love. It's frozen carbon dioxide, and it's called "dry" because it passes from the solid phase directly into the gas phase, skipping the liquid phase entirely, resulting in some AWESOMELY weird and funky behaviors! It's CRAZY-cold, so cold in fact, we only handled the dry ice with a towel or tweezers....NEVER with our bare hands!

We demonstrated its COOLNESS in the following ways....

• froze cooked pasta and flowers by dropping them in acetone with dry ice. (Acetone is good thermal conductor, so it gets really really cold.)

• produced a lot of spooky fog.

• "poured" carbon dioxide gas into a cup on a scale and noted that it weighed more than an equal volume of air.

• used carbon dioxide gas as a fire extinguisher (Don't panic, the fire was a single lit candle).

• made long-lasting carbon dioxide bubbles by adding dry ice to soap solution.

• made the dry ice "squeal" and vibrate after pressing it with a metal spoon.

• inflated a balloon by putting a piece of dry ice inside and then tying off the open end.

Physics: Danger...QUICKSAND!!!

Today the physics group was challenged to figure out the best way to escape from quicksand. To thrash or not to thrash? Before jumping to any conclusions our young scientists decided to model the problem using "ooblek," a mixture of cornstarch and water. Like quicksand, ooblek changes quickly from solid to liquid as a result of changes in pressure making for some really strange behaving goo!

First the kids made their own ooblek - 2 parts cornstarch to 1 part water. Then to be sure it was just the right consistency, we applied the "slap and splash test." If you slap it and it splashes, too much water. If you slap it and nothing happens, you done good! For the most part,there were no casualties, and our scientists proceeded to figure out the best way to exit the quicksand experimenting with plastic animals and action figures. Their recommendation: Don't panic and move slowly.

Corrections

My fact checker (my husband) has just informed me that all of the Sharper Image stores were closed by the end of 2008 after bankruptcy.

Take the SCIENCE IN MOTION Challenge!

Today being the last day of science, seemed like a good time to do the Science in Motion Challenge. The Science in Motion Challenge has two parts: a series of questions relating to the experiments carried out over the course of the year and a few fiendishly difficult science dares including:

• Float a paper clip in water.
• Insert a sharp pair of scissors into a soap bubble without popping it.
• Have a catch with a bubble without popping it.
• Make soap bubbles that are shapes other than spheres.

Armed with their intellect, a sense of adventure, and their lab notebooks, the kids made short work of the questions, the dares, not to mention my back yard!

It's been a great year - I really enjoyed working with your kids!
Have a wonderful summer!

Rebecca

Science Fair 2010

This year's Science Fair was a big success! Our general scientists did some excellent product testing, the physicists' inventions will no doubt be lining the shelves next year at Sharper Image, and the biologists planned and executed some fascinating projects on the human body.

Here is a quick summary of the results from the biology projects:

• Spinning with your eyes closed made you dizzier than with your eyes open.
• Doing exercise slowed down drinking capacity, more so with water than with coke.
• The effects of static electricity were observed the most in people with wavy hair.
• The right hand of righties was more sensitive to temperature than was their left.
• Boys had greater lung capacity than girls.

Our scientists had a lot more to say than just the bottom line, so please ask the kids about the challenges they faced carrying out projects with human subjects.

Kudos to all our budding young scientists as well as their supportive families and friends!

Physics and General Science: DIY Ice Cream Maker

This week we did a pretty COOL trick....we made ice cream, without a freezer, using our own DIY ice cream machine. How did we do it and what does it have to do with science?

The kids poured the ice cream ingredients (milk, vanilla, and sugar) into a small plastic bag. Then they placed this bag into a larger bag filled with a lot of ice and a lot of salt. The whole business was then wrapped in a towel and then shaken until the milk mixture solidified. The rock salt caused the ice to melt quickly and reach a sub-zero temperature, so that the resulting freezing salt water could quickly absorb heat from the milk mixture, giving you yummy, delicious ice cream or at the very least, a super-cool milk shake.



Here's the procedure in case anyone wants to try it at home.

1. Pour ¼ cup of milk into a sandwich-size zip lock bag.
2. Add 1 teaspoon of sugar and a couple drops of vanilla extract.
3. Close the bag carefully, while getting rid of the extra air.
4. Mush the bag around to mix the contents.
5. Place this bag in another sandwich zip lock bag, remove the extra air, and seal.
6. Fill a 1-gallon zip lock bag with ice and a half a cup of rock salt.
7. Place the double bagged milk mixture inside the larger bag, squeeze out the extra air, and seal.
8. Wrap each bag in a towel and mix, shake, and churn until the inner bag's contents freeze.

Tips:

* Make sure all bags are closed, especially before you start shaking up the bag of ice and salt.
* Double-bagging the milk mixture is important, to help reduce the odds of salt penetrating the bag and getting into the ice cream (yuck!).
* Err on the side of too much ice and too much salt.
* Try to keep the milk mixture bag in the middle of the ice, and especially in the middle of the melted salt water.
* See what happens if you add different flavors like chocolate syrup or lemon juice.

Physics: Triangle Appreciation Day

Last week we carried out a few experiments demonstrating the power of the triangle. The kids built squares and triangles out of straws and tested them to see which shape is more stable. Triangles won, and they used this fact to strengthen a 3-D cube made out of modeling clay and toothpicks and then cubes made out of straws and paperclips.

Check out how strong this cube is – that's some seriously HEAVY material!

Science Fair coming soon!

Physics: Simple Machines

This week the kids reviewed levers and learned about the following additional simple machines: pulley, screw, wheel and axle, and wedge.
REMINDER: In preparation for the upcoming Science Fair, this coming week will be pretty intense....we're meeting Sunday, from 10:00-12:00 (there will be pizza for our budding inventors) as well as our normal meeting time, Tuesday 2:15-3:15.

Physics: Science of swings

This week the kids set out to understand what a swing is by building them out of K'nex and Legos. Once we had a few models to compare, we were able to consider what sorts of changes we could make to the design to affect the swing's period, the time it takes to swing back and forth. The kids came up with a few different variables: the mass of the swing, the length of the swing, and the height or angle at which you start the swing. Next week, we plan to test these variables in the field, on actual swings. Weather-permitting, we'll visit a playground and see which of these variables affects a swing's period the most.

Physics: Build a motor

As you may remember, a while back the kids magnetized an iron nail by wrapping it in many loops of wire and attaching the ends of the wire to a battery. This week the kids expanded on this principle to build a motor. Once again they made a coil of wire and inserted it into a circuit by resting it on 2 metal struts attached to a battery. Then they placed a small round magnet on top of the battery. The electro- magnet (the loops of wire connected to the battery) and the regular magnet exerted magnetic pulls and pushes on each other so that the coil rocked back and forth.

To make it spin, we had to get creative...the kids put white out on the tops of the wire where the coil made contact with the metal struts. Doing this broke the circuit half the time. What did this do? When the circuit was closed, the coil became magnetic, which gave it an initial push away from the other magnet. As the coil made half a turn, the circuit turned off, and the momentum kept it spinning, bringing the coil full circle.

In a perfect world, the coil would continue spinning until the battery ran out, but alas, we don't live in a perfect world. Besides gravity and electromagnetic forces, the kids had to contend with the most challenging force of all....FRICTION. The need to reduce friction explains why this activity took an hour, and not 5 minutes, and why by the time they got home, the motor may have stopped working.

Physics: Sink or swim

Today we continued our investigation of why things float. The kids were given various materials and a tub of water and were challenged to fill 3 canisters so that one floated, one sunk, and one was suspended. As you might imagine, sinkers and floaters were relatively easy to manage, but suspending a canister under water was a bit trickier.

Having already established last week that floating and sinking isn't JUST about weight, we considered a new concept, DENSITY, how much mass is stuffed into a particular space. The kids then measured each canister's mass and volume and then calculated whether its density was greater than, less than, or equal to 1 g/ml, the density of water. We concluded that objects with densities greater than water sunk, less than water floated, and equal to water were suspended.

We concluded by measuring the mass of a canister of oil. Taking into account the volume of the canister, the kids correctly predicted that it would float. Then we looked at some salad dressing I conveniently forgot to put away last night after dinner.

Physics: Whatever floats your boat

This week the kids were given 6 items to analyze. They were assigned to order them by weight, first by guessing, and then by measuring the weights with a scale. The kids were pretty surprised by how wrong their guesses were. We wondered why it was that some things, like say, a large piece of styrofoam "feel" lighter than others when they actually weigh more. We got some clues when we moved on to part two of the lab: testing each item to see if it floats or sinks in water. Wouldn't you know it, the things the kids thought were light, were floaters, and the things they thought were heavy, were sinkers. However, contrary to our expectations, whether something sinks is NOT simply about weight.

Then each kid was given a lump of clay. After observing that it too was a sinker, they were challenged to build a boat out of said sinking clay, and not just that, but a boat that could carry cargo (any number of marbles, also sinkers). After some trial and error, the kids figured out which shapes worked best.

Then just for fun, the kids made bouncy balls out of water balloons.

Physics: Which ball is the bounciest?

This week we looked at another example of Newtons 3rd law, the law of action and reaction to understand why balls bounce. The kids compared 3 types of balls: a super-ball, a tennis ball, and a basket ball to see which one had the highest bounce height and which one bounced the greatest number of times. Most of the groups found the super-ball to be the bounciest. We wondered what about it makes it so bouncy. Next week we will continue this investigation to look at why certain materials bounce more than others.

Physics: Good Vibrations

This week we started a new topic: SOUND. We talked about what a sound is and experimented with sounds produced by different materials. The kids made oboe-like straws, plucked rubber bands of different widths and lengths across shoe boxes, bounced wooden sticks off the side of tables, and struck water-filled glass jars, noting in each case how different changes affected the pitch. Finally, the kids used their observations to created their own instruments, and then we had a concert!

Physics: Making magnets

A couple weeks back the kids discovered that iron-containing metals can themselves become magnets if they are rubbed by a magnet. We used this observation to build compasses in 3 easy steps:

1. Rub a light-weight iron needle with a magnet (always in the same direction) 50 times.
2. Stick it through a thin piece of Styrofoam.
3. Set the whole business afloat in a bowl of water and observe how try as you might, you cannot prevent the needle from pointing along a north-south axis.

Afterward, the kids built electromagnets. In an electric circuit, the movement of electrons creates a magnetic field, but because it is so weak, you might not notice it. However, if you build a circuit with MANY loops of wire, all in the same direction, each loop reinforces the strength of the magnetic field.

Physics: What color is it really?

This week we did 2 mini-experiments to investigate how we perceive color. The first was with spinning color wheels. The kids compared the patterns of the discs when still to the patterns they saw when the discs were spun. The second mini-experiment involved looking at magazine pictures under the microscope and comparing the images seen with the naked eye to the colors revealed at greater magnification. Both experiments demonstrate how our brains process stimuli that our eyes receive in either in too short a time or in too small a space.

With the spinning color wheels, when we see 2 colors within a short period of time, our nervous system combines the colors. Pictures in a magazine are actually made up of patterns of tiny dots, placed closely together. Once again your brain can't process them separately and instead combines them to produce the experience of various colors. What is especially cool about the magazine pictures is that no matter what color you "see," when examined under the microscope you realize that the image is made up of just 3 colors: magenta, cyan, and yellow (aka red, blue, and yellow). By producing images that include different ratios of the primary colors, you can get just about any color.

Next time your kids paint, just give them red, blue, and yellow - make them to do the work!

Skeletons in your closet

I love chanukah! Lighting the menorah, eating latkas, and of course let's not forget the gifts. On day 6, I received the best gift ever...an animal skull! Two kids were hiking in the Carmel forest and came upon this beauty and managed to lug it home. Too good an opportunity to pass on, we skipped the usual physics and did some skeletal analysis. The kids examined a couple different skulls and mandibles and used their observations to infer a number of things about the animals including: what they ate, how they walked, and what they used more: smell or sight.
Finally they made educated guesses about the identities of the skulls. I will be consulting with my friend Efrat, the vet, to get a final verdict. Look at the 2nd picture to see if you can id the skulls.

Physics: Magnets

After completing their quizboards (hopefully 2 days later they're still intact), we started a new unit: MAGNETS

The kids investigated which materials are magnetic, compared the strengths of different magnets, learned how to turn iron nails into weak magnets, observed the effects of magnets on compasses, and used iron filings to observe magnetic fields.

Physics: Parallel Circuits

Before completing their houses, the kids learned how to make parallel circuits as well as the advantages for doing so.



The finished houses look great! Very high-tech with lights, alarm systems, fans, doorbells, and one group even attempted to make a swimming pool (don't worry this part did not include a circuit!).