Dot Physics

I know I saw this demo somewhere. Maybe it was at an AAPT conference a few years ago. I have always wanted to build this, but never got around to it. Until now. Here is the demo (it is easy, you should make one too)

So, how does this work? I think [...]

You know I like demos, right? This one is quite fun to do even in a class. The basic idea is to take a bucket of water and swing it around in a circle over your head. Simple, but if you have never done this one, it can be a little intimidating. [...]

Maybe this is a little old (in internet age), but it is a great example. Here is the Loop-the-loop stunt from the show Fifth Gear.

I like this. First, it is a bold stunt. But also, there is some good physics here. Though, most importantly, the Fifth Gear producers were kind enough [...]

I found this in the most recent issue of The Physics Teacher (September 2009). Surprisingly, there were several good articles in this issue. One article discusses a doable version of the Millikan Oil drop experiment. Maybe you are not a (or were not) a physics major, so you might not be familiar [...]

Thanks to Nick for showing me this video (Check out his blog – Fine Structure):

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Check this out (saw it on the interwebs):

It’s this video inside a bus of a girl hitting the roof. My first thought was: well, she just jumped. But something was odd. She was in the air too long. Well, of course this calls for a video analysis (using Tracker Video Analysis). [...]

Every introductory astronomy text and most intro physics texts talk about tides. The usual explanation is something along the lines of:

The moon exerts a gravitational force on the Earth and all the stuff on the Earth. This force decreases with distance (1/r2). Thus the moon pulls greater on [...]

So, I built a new accelerometer. Why? The jelly-jar one was just not doing it for me. Plus, the cork was starting to make the water all yellowy. It was a good start, but I can do better. What was wrong with the jelly-jar one? First, it didn’t let the cork move very far before hitting the wall. Second, it was kind of hard to see exactly where the cork was. Lastly, there was no way to get a reading of the acceleration from the jelly-jar. Now, I am going to fix that.

Yesterday, I uploaded a post from my old site about slowing down time to make videos look like they were on the moon. If you haven’t read that, the short story is that it doesn’t look right when speed Apollo videos up so that the acceleration is -9.8 m/s2.

What started that whole thing was [...]

Note: This is a repost from my old site. Time to move it over.

First, what is different about motion on the moon and on Earth? Since the moon has a smaller mass in spite of its smaller size*, the moon has a smaller gravitational field. The gravitational field on the surface of [...]