Swans on Tea

A few days ago I was relating the cans-in-a-blanket problem, and retelling the vacuum joke and story to someone who had not yet heard them. One of my colleagues commented on a problem he had been given during an interview, also involving cans of soda:
You have two cans, one filled with ice and the [...]

School kids measure distance to the Moon
The students analysed an mp3 recording of the conversation between Neil Armstrong on the surface and ground control in Houston in which he utters his famous “one small step” speech. The recording is available on the NASA website.
They noticed an echo on this recording in which sentences from Earth [...]

Rhett asks a straightforward question over at Dot Physics, in A blanket and cold stuff
Suppose you put take two identical cans of soda out of the fridge and place them on the floor in the middle of a room. One can you leave alone and one can you cover with a wool blanket. After an [...]

A UV LED flashlight. Just checking on what fluoresces. Among the more interesting, we have the security stripe of a $20 bill

A Mr. Clean bottle shows both the label and the cleaner fluorescing

and some vitamin B complex (I think the B-12 is the main culprit here), dissolved in some vinegar, and spilled on [...]

Pendulum Trajectory
[T]he trajectory of a pendulum, as seen from the bottom.
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MagnetNerd
Hi, I’m Rob Gallagher and I’m a MagnetNerd.
[…]
Neodymium Magnets are just plain cool. It’s totally amazing how something so small can have such strong magnetic forces. I enjoy showing others the amazing things that can be done with Neodymium Magnets. So far I have created 53 Videos of my experiments and designs on YouTube and [...]

Kent’s Video Chemical Demonstrations

Balloon-powered boat
Which could be a DIY project, I’m sure. You could adapt the idea to a DIY hovercraft as well.

Life’s the same, except for my shoes
Stereograms! Make Your Own 3D Camera for $15 or Less
If you happen to have two digital cameras, you can skip some of the steps, like getting the film developed and scanning the pictures. I was able to get my hands on a second camera; I found that [...]

My recent post on Haidinger’s brush reminded me of another optical phenomenon I have observed, and one that is a bit easier to see: the Pulfrich effect.
The Pulfrich effect is a phenomenon that gives the illusion of depth based on the response time of different light levels in the eye and how the brain [...]

Freezebubbles
It’s very cold tonight, so we played with bubbles. If you blow them upwards enough they have time to freeze on the way down.
Damn. I wish I’d thought to do this when the temperature dropped to ~ 0ºF while I was home.

And nuke it.
Things to do in a microwave #2: Create a plasma
It just so happens that grapes are about the size of the wavelength of microwaves, which is important. And grapes also have sugars, which make them into dielectrics. (There are other fun things you can do with grapes because of this). [...]