Using only the phone\'s (Android) built in accelerometer, how would I go about finding its velocity?
I have been tinkering with the maths of this but whatever funct
Integrating acceleration to get velocity is an unstable problem and your error will diverge after a couple of seconds or so. Phone accelerometers are also not very accurate, which doesn't help, and some of them don't allow you to distinguish between tilt and translation easily, in which case you're really in trouble.