Does a 1/4 mile timing application exist?

[morrisman1]

Ok i have a macbook, it has a three axis accelerometer in it to sense when it is dropped (turns off harddrive) but its not restricted to using that. there is an application for iphone and ipod touch that uses the accelerometers in those to estimate 0-100 and 1/4 mile etc, just like the g-tech unit. Has anyone heard of an application that can use the macbook's accelerometer in the same way?

thanks

 

[gr8tfly]

Just some demo apps, but it could be done.

 

[alphaod]

You can't measure distance with an accelerometer. It only measures acceleration.

Unless we're not talking about the same thing.

 

[gr8tfly]

You can't measure distance with an accelerometer. It only measures acceleration.

Of unless we're not talking about the same thing.

The iPhone apps just look for a change in acceleration [after 1/4 mile], assuming you let off or start braking after the timed distance. Not too accurate a method, though. Otherwise, someone just has to hit the stop button. Still it could be off by a couple hundred ms.

 

[morrisman1]

You can't measure distance with an accelerometer. It only measures acceleration.

Unless we're not talking about the same thing.

i presume you have forgotten calculus. Integrate the acceleration curve and you get the velocity curve, integrate that and you get distance. The app has the simple job of taking acceleration and drawing the two other graphs and having flags for when d=400m give the time and velocity*. The accelerometers in the macbooks are pretty good, with a well written program id expect the accuracy to be about ±0.3s

Dynolicious on the iphone does this but i dont have one of them