Lensyl Urbano – Page 99 – Montessori Muddle

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.

Anomalous Motion: Optical Illusions

Not-a-GIF — Image via boingboing.net (Pescovitz, 2011).

While I do like to use animated gifs, these apparent animations are actually still images that, because of the arrangement of colors and shapes, your brain interprets as moving. Akiyoshi Kitaoka has an extensive gallery. It comes with the warning though: ‘works of “anomalous motion illusion”, … might make sensitive observers dizzy or sick.’ (Kitaoka, 2011).

rotsnake — Rotating Snakes, by Akiyoshi Kitaoka. Click the image for a full sized version where the rotation is accentuated.

The History of the Periodic Table

Vis_tellurique_de_Chancourtois — 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.

Sub-atomic particles

A proton is made of three quarks. Image by Arpad Horvath via Wikipedia.

LiveScience has a neat little slideshow that briefly describes the different types of elementary particles. These include the particles, like quarks that make up protons, which have been observed, as well as sparticles and the Higg’s boson that have not.

CERN also has a nice page describing the Standard Model.

The Standard Model of elementary particles. Image by MissMJ via Wikipedia.

Why Gold is Precious

precious-metals — The precious metals are those few that are not gasses, and not reactive. Of these, only gold (Au) and silver (Ag) are not extremely rare and hard to extract and work.

A while back, I posted a radio article by Planet Money on why gold is so valuable, and has been used for money for so long (God, Glory and GOLD: but why gold?). They’ve now created a nice video explaining the same thing. Though there’s less detail, the dramatic visuals (of the reactivity of sodium for example) make it quite interesting.

Sub-atomic Physics: The Significance of 0.8%

When it comes to particle physics … [m]easuring something once is meaningless because of the high degree of uncertainty involved in such exotic, small systems. Scientists rely on taking measurements over and over again — enough times to dismiss the chance of a fluke.

— Moskowitz (2011): Is the New Physics Here? Atom Smashers Get an Antimatter Surprise in LiveScience

New research, out of the Large Haldron Collider in Switzerland, shows a 0.8% difference in the way matter and antimatter particles behave. This small difference could go a long way in explaining why the universe is made up mostly of matter today, even though in the beginning there were about equal amounts of matter and antimatter. It would mean that the current, best theory describing particle physics, the Standard Model, needs some significant tweaking.

The Standard Model of elementary particles. The LHC experiment looked the charm quarks (c), and their corresponding antiquarks, which have an opposite charge. Image by MissMJ via Wikipedia.

0.8% is small, but significant. How confident are the physicists that their measurements are accurate? Well, the more measurements you take the more confident you can be in your average result, though you can never be 100% certain. The LHC scientists did enough measurements that they could calculate, statistically, that there is only a 0.05% chance that their measurement is wrong.