Sometimes you want to just kick back with a cool beverage of choice, and you know...? Do something crazy with your iPad!! Maybe something radical like: observe the conservation of angular momentum applied to a smooth body in motion as it turns ever more rapidly around it's center of mass. Huh, you say?!.. Ever see a skater speed up in a spin just by pulling in her arms? That's an application of exactly what I'm talking about, and you can learn a lot more about these interesting physics principles using the HyperPhysics app!
A cool thing about Hyperphysics is that it is developed by Rob Emery, who wrote the app as part of his thesis. The Hyperphysics card views hosted at Georgia State University are some 14,000 pages of information on everything from common household electrical circuitry descriptions to the formative processes that create white dwarf stars. The site registers hits from millions of users all over the world. It is a pretty amazing compilation of on-line physics information that represents some 20 years of work. Rob was able to boil it all down into a handy app in a couple of months, without even a tiny inkling of how to write an iPhone application. A pretty amazing accomplishment.
The app itself is more or less card views of the content that you find in the main web site. You navigate through the mindmap-looking presentation to find linked and related content to a topic by tapping on it's callout. The app lacks a TOC, index or search capability, which I'm hoping will be coming in V2. I'd also like the mindmap to be more interactive, if possible. A 3D animated view would be cool, for example. Still cramming all this info of formulae, text and images into a usable app for iPhone (the app is 150MB) that you can take with you anywhere is quite useful.
HyperPhysics also has an on-line page rendered version of the main web-site, which has some additional features not found yet in the app version. You can do some neat stuff like compute the force of a car crash, figure out stopping distance on a slippery road, or check out what's going on in the on-line study group. Neither the site or the app are overly fancy or dynamic, but a true geek likely doesn't care about that much anyway. The web version did crash a few times.
I was able to find some weather-related formulas that brought back memories of my time as a weather geek; like how to calculate relative humidity. See below shot of an old Skew-T diagram I rummaged up from a box in the garage. The Skew-T was a vertical sounding diagram chart we used for plotting and calculating parameters like relative humidity (data from a station weather balloon). The one below I had marked up with index calculations as a study reference. Back in the day we did all kind of analysis by hand, but I admit that for most of the time I was a qualified weather forecaster, we had finally switched over to decent computer systems that automated most of these kinds of calculations...
You can check out Rob's app in the app store at the link above. It's somewhat pricey at $6.99, but there is a ton of information in there. It could use a few tweaks (like the ability to rotate the iPad version especially), but I love to see technology being used for a higher pursuit in life, and wanted to give Rob some props for creating a worthwhile app. He is working on some of the items I mentioned. Now if I could just find that formula for going backwards in time... Oh yeah, that one hasn't been invented yet, or probably not even possible!? Hmm, maybe the answer is somewhere in HyperPhysics!