One of the most basic things students do in a physics lab is to collect data and use that to build a model. Most of these models come in the form of a mathematical function. But here is the problem.

If you want to know exactly how far, and fast, you've run, then a speed-and-distance monitoring (SDM) watch is an essential piece of kit. Timex, Garmin and Navman produce SDMs that use satellites to ...