Eptsoft offers Electrical, Mechanics, and Maths as educational freeware. It includes a wide range of scientific and engineering formulas, calculators, and other tools in a series of clearly illustrated pop-up windows. It also has the most annoying and frustrating nag screen we've ever encountered in so-called freeware. It pops up every 20 seconds or so, obscures the entire screen, and must be closed manually to continue our "evaluation." You have to pay ("donate") to remove the ads and actually use the program. It's cheap, but it ain't free. Did we mention it's intensely annoying, too? The "free" version also disables some features.
Electrical, Mechanics, and Maths consists of a tree view on the Contents menu accessing a long series of pop-ups defining scientific and engineering laws, theories, principles, and problems grouped under its three broad categories. (The software is British; "Maths" is "Math" to Yanks). Many offer illustrations, graphs, or equations, and most seem to have configurable options. For instance, under Ohm's Law, the Current tool has settings for Voltage and Resistance. Under AC Measurements, we could calculate the period of an AC sine wave in peak amplitude and frequency. We could open as many of these windows simultaneously as we needed and move them around the screen, though we couldn't resize them individually, which would be a helpful option. But one problem overrode all others, namely the fact that we couldn't do anything with this program for more than a few seconds before having to close the nag screen again.
In the original movie "Arthur," Dudley Moore's title character encounters what may be the most over-the-top nag in filmdom. Eptsoft's is the Perry's Wife of nag screens. Somehow it's all the more annoying that they only want you to fork over a buck (quid, actually) or three, but perhaps there's justice in the fact that most users will simply uninstall it before they get that far. What a shame, since it looks like Electrical, Mechanics, and Maths has something to offer on merit.