Tag: video

Slingshot Physics

Slingshots came up the other day in physics when we were talking about tension in strings when they’re held at an angle. The larger the angle the greater the tension in the string, which is why it’s harder to do pullups on an overhead bar when your hands are spread apart.

The concept of elasticity also came up. It is the elasticity of the rubber band, its ability to return to its original shape, that provides the potential energy when you pull it back.

Smarter Every Day has a video up that glances at the physics of slingshots.

One of the neater things the video shows is one experiment where they were aiming for a pumpkin but missed. The shot went too low, knocking the piece of wood the pumpkin was sitting on, and practically all the momentum of the shot was transferred to the wood: the shot looses all its velocity while the wood takes off. Once its support is gone, the pumpkin just drops vertically — there’s no horizontal motion — making this also a good demonstration of inertia.

The History of the Periodic Table

Fitted to a cylinder, the elements on this periodic table would form a spiral. Image via Wikipedia.

Spurred by Philip Stewart‘s comment that, “The first ever image of the periodic system was a helix, wound round a cylinder by a Frenchman, Chancourtois, in 1862,” I was looking up de Chancourtois and came across David Black’s Periodic Table Videos. They put things into a useful historical context as they explore how the patterns of periodicity were discovered, in fits and starts, until Mendeleev came up with his version, which is pretty much the basis of the one we know today.

The cylindrical version is pretty neat. I think I’ll suggest it as a possible small project if any of my students is looking for one. You can, however, find another interesting 3d periodic table (the Alexander Arrangement) online.

The Case Against the Electoral College

C.G.P Grey makes the case against the Electoral College in video form. He starts with how the Electoral College Works and continues with a well reasoned polemic against it: he’s big into democracy — one person, one vote.

How the Electoral College Works

The Trouble with the Electoral College

Murmuration: A Flocking of Birds

Amazing footage of an enormous flock of birds in flight by Sophie Windsor Clive.

Murmuration from Sophie Windsor Clive on Vimeo.

Brandon Kelm explains a little of how it works, mostly using terms like “scale-free correlation” and “criticality”, which pretty much sums up that we don’t know a lot about the phenomena.

NetLogo has a nice little Java model showing an attempt at simulating flocking. They give a good description of how there model works.

(via The Dish)

Doodling is Good!

To Doodle: to make spontaneous marks to help yourself think.
–Sunni Brown (2011): Doodlers, unite! (at 3:19) in TED.

Unfortunately, teachers are usually opposed to doodling in class. (Image from Sunni Brown's TED talk.)

Doodling on a notepad is often seen as evidence that a student is not paying attention. Very much to the contrary, argues Sunni Brown in this TED talk:

Studies show that sketching and doodling improve our comprehension — and our creative thinking.
— TEDtalksDirector: Sunni Brown: Doodlers, unite! on YouTube.

She describes doodling as a, “preemptive measure to stop you from loosing focus.” In addition, doodling helps integrate all four modes of learning (visual, auditory, reading/writing, kinesthetic) as well as helps provoke an emotional response, all of which greatly aid retention of information and creative thinking. Finally, doodling is most useful when we’re trying to process a heavy, dense load of information.

Brown has more details in her article in .net, Why the Doodle Matters.

(hat tip: The Dish)

Bug Power Generator

Most power plants create electricity by spinning a magnet while it’s inside a coil of wire. That how coal power plants do it, it’s how hydroelectric power plants do it, it’s how wind plants do it, it’s even how nuclear power plants do it; solar power panels don’t do it this way, however. The coal and nuclear plants, for example, boil water to create steam which spins the turbine that rotates the magnet.

In theory, you can use any type of power source to spin the turbine, including people power. On bicycles, you can use them to power your lights. But because you’re now using some of your mechanical energy to create electricity, it will slow you down a bit. Newer, hub dynamos, however, are apparently quite efficient.

So, in theory, you could use any type of animal to generate electricity. Including, for example, using bugs to charge your iPod.

I love how he holds up the voltmeter 34 seconds into the video to prove that his device works.