Trig Tour is one of the excellent HTML5 Math PhET Simulations from The University of Colorado Boulder. There are numerous PhET simulations covering Physics, Biology, Chemistry, Earth Science and Mathematics. Note the growing collection of HTML5 versions which will work across all platforms and devices.
You can download all the HTML5 sims so they are available offline in an app. Available fir iOS and Android for only $0.99 / 89p which supports HTML5 sims.
PhET Balancing Act working nicely on my phone!
Staying with Mechanics, one of my favourites now available in HTML5 collection: Projectile Motion.