Natural World – Page 58 – Montessori Muddle

Build Your Own Solar System: An Interactive Model

National Geographic has a cute little game that lets you create a two-dimensional solar system, with a sun and some planets, and then simulates the gravitational forces that make them orbit and collide with each other. The pictures are pretty, but I prefer the VPython model of the solar system forming from the nebula.

The models starts off with a cloud of interstellar bodies which are drawn together by gravitational attraction. Every time they collide they merge creating bigger and bigger bodies: the largest of which becomes the sun near the center of the simulation, while the smaller bodies orbit like the planets.

This model also comes out of Sherwood and Chabay’s Physics text, but I’ve adapted it to make it a little more interactives. You can tag along for a ride with one of the orbiting planets, which, since this is 3d, makes for an excellent perspective (see the video). You can also switch the trails on and off so you can see the paths of the planetary bodies, note their orbits and see the deviations from their ideal ellipses that result from the gravitational pull of the other planets.

I’ve found this model to be a great way to introduce topics like the formation of the solar system, gravity, and even climate history (the ice ages over the last 2 million years were largely impelled by changes in the ellipticity of the Earth’s orbit).

National Geographic’s Solar System Builder is here.

Signs of Water on Mars?

Water is necessary for life as we know it, which is why the search for life on other planets and moons in the solar system has been focused first of all on finding water. NASA now reports signs of water on Mars. Salty water perhaps, and even now there is no direct evidence that it is water and not some other fluid, but this is the first evidence of there being liquid water on Mars today.

The video above explains, and the BBC has a good article.

Appropriate Technology: Innovation with Light

Not a lot of light penetrates the galvanized steel roofs that are ubiquitous in slums around the world. Alfredo Moser came up with one ridiculously cheap solution (via the World Social Forum, 2011).

While this the kind of cheap, elegant solution I would go for in a heartbeat, I’m pretty sure my wife would veto. For the more stylistically conscious – and for people with a bit more money in their pockets – there are $2.00 LED lights advocated by The Appropriate Technology Collaborative (ATC). A lot of people in dire poverty live in the slums, but that’s not the case for everyone.

The ATC’s seems to focus on projects designed by university students and implemented in the third world. If they work, the designs are published with a Creative Commons license so that other Non Governmental Organizations (NGO’s) that work in poorer countries can use and distribute them. Their blog has a lot of good information. And, there’s also the Global Bucket project that I’m still keeping an eye on.

Interactive Model showing the Kinetic Energy of a Gas

I really like this little video because it’s relatively dense with information but its visual cues complement each other quite nicely; the interactive model it comes from is great for demonstrations, but even better for inquiry-based learning. The model and video both show the motion of gas molecules in a confined box.

In the video, the gas starts off at a constant temperature. Temperature is a measure of how fast the particles are moving, but you can see the molecules bouncing around at different rates because the temperature depends on the average velocity (via Kinetic Energy), not the individual rates of motion. And if you look carefully, you notice the color of the particles depends on how fast they’re moving. A few seconds into the video, the gas begins to cool, and you can see the particles slow down and gradually the average color changes from blue (fast) to red and then some even fade out entirely.

In the interactive, VPython model I’ve put in a slider bar so you can control the temperature and observe the changes yourself. The model is nicely set up for introducing students to a few physics concepts and to the scientific method itself via inquiry-based learning: you can sit them down in front of the program, tell them it’s gas molecules in a box, have them observe carefully, record what they see, and then explain their observations. From there you can branch off into a lot of different places depending on the students’ interests.

Temperature (T) – a measure of the average kinetic energy (KE_average) of the substance. In fact, it’s proportional to the kinetic energy, giving a nice linear equation in case you want to tie it into algebra:
$! T = c {KE}_{average}$
where c is a constant.

Of course, you have to know what kinetic energy is to use this equation.
$! KE = \frac{1}{2} m v^2$
Which is a simple parabolic curve with m being the mass and v the velocity of the object.

The color changes in the model are a bit more metaphoric, but they come from Wein’s Displacement Law, which relates the temperature of an object, like a star, to the color of light it emits (different colors of light are just different wavelengths of light).

$! T = \frac{b}{l}$

where b is another constant and l is the wavelength of light. This is one of the ways astronomers can figure out the temperature of different types of stars.

Notes

The original VPython model, from Chabay and Sherwood’s (2002) physics text, Matter and Interactions, comes as a demo when you install their 3D modeling program VPython.

I’ve posted about this model before, but I though it was worth another try now that I have the video up on YouTube.

Match Stick Rockets

A great, simple, and slightly dangerous way of making rockets. There are a number of variations. I like NASA’s because they have a very nice set of instructions.

match_rocket_howto — How to make a match stick rocket. By Steve Cullivan via NASA.

With a stable launch platform that maintains consistent but changeable launch angles, these could be a great source of simple science experiments that look at the physics of ballistics and the math of parabolas (a nice video camera would be a great help here too) and statistics (matchsticks aren’t exactly precision instruments).

Atlantis Reentry

573233main_image_2014_946-710 — Atlantis re-enters the Earth's atmosphere for the last time. Image from NASA.

The last re-entry of the space-shuttle was captured from the International Space Station.

Glassblown Hermit Crap Shells

Robert DuGrenier blows glass shells for hermit crabs. They’re pretty amazing. Aquariums are also using them because they let you see all the parts of the crab that are usually hidden inside the shells.

Notes

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