If you don’t already own one, you’ve no doubt seen
advertisements for them on television. I am referring to so-
called “smartphones,” which can change the orientation of their
display, from Portrait to Landscape, depending on how you hold
them. They can do that because they contain a fingernail-sized
chip inside, which senses the acceleration of gravity, and
adjusts the display accordingly. Resourceful programmers have
come up with a number of other applications, or “apps,” for
these phones, which take advantage of the on-board ability to
sense acceleration. If you only use a plain old-fashioned cell
phone, you still have a number of these devices around you.
Automobiles use them for airbag deployment, stability control,
and braking systems. Videogame controllers use them. And digital
cameras use them to stabilize an image. Because of their low
cost, small size, and low power requirements, these devices have
made their way into a myriad of consumer, industrial, and
military products. They are called accelerome