Category Archives: Matter and Energy

Rube Goldberg Machines

rube_napkinBy now, you have probably seen the OK Go video that everyone is talking about, featuring the Rube Goldberg machine. That machine took months to build, and days to film. You can learn more about how the contraption was built here. We were wondering, who started this whole contraption building craze in the first place?

What people call “Rube Goldberg machines” are based on the cartoons of Rube Goldberg, whose work appeared in newspapers in the early 1900′s. The contraptions usually were incredibly complicated ways to do something simple, like scratch your back or mail a letter.

We really like this blog post about the greatest Rube Goldberg contraptions of all time. What do you think, which one is the best?

Experiment: How Does Electricity Make Things Go?

Principal Investigator: Celeste

Research Assistant: Jeffrey

Date: April 21, 2007

This weekend we decided to do another experiment with a science kit. This time we used a Snap Circuits Jr. electricity set to create a motorized fan. To our surprise, when we flipped the switch, the fan propeller ran for a moment, then suddenly launched itself into the air and flew across the room.

This experiment has three separate areas of science and math: The electrical circuit (to make the fan go), the part that makes the fan take off (called aerodynamics), and the grid that we use to build the electrical circuit (which a mathematician would call a Cartesian coordinate system, but we just refer to as “the grid”).

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The Snap Circuits Jr. kit is an excellent way for kids to learn about electricity. It makes it easy to create electrical circuits without having to do any wiring. The set comes with a plastic grid with pegs on it that lets you easily snap various parts into place. These parts include motors, switches, lamps, noisemakers, and connectors (which take the place of wires).

To build the electric fan, we followed the instructions in the kit. We started by laying out the pieces we needed, including the propellor, the fan motor, an on/off switch, and about six connectors.

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One of the things we learned when putting together contraptions with the Snap Circuits Jr. set is that you need to build a circuit — a complete circle of connectors going into and out of the batteries — to power something using electricity. The instructions make it pretty easy to put a circuit together by mounting the various pieces on the grid, but we found it a little hard to read the numbers and letters on the grid’s coordinate system. So we made them a little darker by drawing over them with a Sharpie marker.

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Once we could read the coordinates on the grid, it was simple to put the components in place. We started with the batteries and the switch.

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After that we snapped the fan motor into place. Nothing’s happening with our contraption yet because there’s no circuit — there’s no way for the electricity to travel through the fan motor to give it power.

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Here we have all the components in place and we’re completing the circuit with connectors.

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Finally we have our circuit, so all we need to do now is place the fan on top of the motor and throw the switch.

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Here’s a picture of the fan running. The fan only ran for a few seconds before it vibrated loose from the motor and flew across the room. We know that fans that spin around fast enough are pushing air downward, which makes the fan want to move in the opposite direction. In this case, the air goes down, so the fan wants to go up.

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We didn’t expect to see the fan fly into the air, though. This is the kind of result that scientists refer to as “exciting and unexpected”. When scientific investigators announce exciting and unexpected results, they are usually either ridiculed, given large research grants, or both.

The fan launching itself across the room was so exciting that we decided to make a video of it for your enjoyment.

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Experiment: Which Materials Conduct Heat Best?

Principal Investigator: Celeste
Research Assistant: Jeffrey
Date: March 18, 2007

Over the weekend we picked up a Ein-O Science Kit at a local game store. On Sunday we did one of the experiments in the box. The Ein-O kits are pretty neat; they have instructions on how to do the experiment along with most of the materials you need.

Our Ein-O kit has four experiments, all having to do with heat. Our experiment demonstrated how different kinds of materials conduct heat. A conductor is a material that energy can pass through. So our experiment tried to show how heat travels through different kinds of materials.

In the experiment, we got a ceramic bowl from our kitchen and attached four types of material to the inside of the bowl. The kinds of material were: a wooden pencil, a plastic tube, a plastic ruler, and a metal spoon. All of the materials except for the metal spoon were included in the Ein-O kit.

Heat-Conducting Materials Experiment: Materials

To stick the materials to the inside of the bowl, we used bits of modeling clay, which was also included in the kit.

Heat-Conducting Materials Experiment: Materials in Bowl

The kit also included some plastic marker discs that we stuck onto the materials with some butter. The idea is that the warm water in the bowl would travel up the materials and melt the butter, causing the plastic markers to slide off the materials. The materials that were better heat conductors would melt the butter more quickly.

Heat-Conducting Materials Experiment: Butter and Markers

After the materials were stuck to the inside of the bowl, we filled the bowl with warm water. It took us a few trials to figure out how much water to use and how warm we needed to get it. In our first trial, we heated 500 milliliters of water for 120 seconds, which made the water pretty hot. This turned the modeling clay to sticky goo after we poured it into the bowl. We noticed that if the modeling clay got too hot, it was too soft to hold the spoon onto the side of the bowl and the spoon would fall over. In our final successful trial, we used 400 milliliters of tap water warmed in the microwave for about 75 seconds.

Heat-Conducting Materials Experiment: Failed Trial

We also had to make sure not to let the warm water touch the modeling clay. We did this by moving the modeling clay up to the rim of the bowl in our third trial. There was one last problem, though. In the third trial, we placed the markers too high, and the heat wasn’t strong enough to travel up the materials to melt the butter and move the markers.

During all the trials Celeste wrote down the time that we started and finished. During the third trial we waited about twenty minutes for something to happen, but because the markers were so high, nothing ever happened. During the third trial Celeste spent much of her time drawing pictures of princesses in her research notebook.

Finally, in the fourth trial, we moved the markers down so they were closer to the water. This time we were able to figure out from our experiment that the metal spoon conducted heat much more quickly than the wood or plastic. The marker slid off the spoon about three minutes after we poured the warm water into the bowl.

Heat-Conducting Materials Experiment: Success!

We don’t know exactly how long it took the butter to melt, because at the time the marker slid off the spoon, we were downstairs helping Mom unload groceries from the car. But we know that the spoon conducted heat the best because when we got back upstairs, none of the other markers had moved.

We’ve posted more photos of this experiment over on Flickr.

What Is Matter?

Your body, your house, your dog, the Earth: all these things are made of matter. Matter is the name that scientists give to all of the substances in the universe.

Is water a kind of matter? Yes, water is a kind of matter called a liquid. Other kinds of liquid include milk and the gasoline we pump into our cars. Water is by far the most common form of liquid on Earth, though — most of the Earth’s surface is covered by water.

Wave your hand through the air. You can feel the air wooshing past your hand. Is the air made of matter? Yes, air is a kind of matter called a gas.  Other kinds of gasses include carbon dioxide (which plants breathe) and helium (which is used to make toy balloons float).

Most of the things you can see or touch are made of matter. Even things you can’t see (like the air) are made of matter. Are there things in this world that aren’t made of matter? Yes: some things are made of energy, which is different than matter. There are lots of ways to see energy in the world. Sunlight is a kind of energy. When a bolt of lightning hits the Earth during a storm, that’s energy too.