If you’re sitting on a chair, and gravity is acting on you, you are not accelerating, because the chair is exerting an equal and opposite force against you. You are resisting nothing. If you are in free-fall, you are accelerating because in an inertial reference frame, your velocity is not constant.

Other than that, interesting finding.

VJing with a wiimote
http://crustea.vjfrance.com/article-130714.html
Thx

and it’s theorized that the earth would stay in a normal orbit for those 8 1/2 minutes, since gravity travels at the speed of light.

If you’re on a train, you see everything going backwards, but everybody sees you going forwards. Same thing is happening here: when the wiimote stands still, it feels a downward force. When it’s falling, it feels no force. The accelerometer isn’t measuring acceleration, it’s measuring the forces acting on the accelerometer, which since F=ma, is proportional to acceleration, which is why it gets the name. It’s really a force-ometer.

HOWEVER! The wiimote uses infrared LEDs to sense its position, I think … see ‘wii don’t need no stinkin’ sensor bar’. Thus it’s a position sensor. Unlike the Gyration mouse! It uses solid-state gyroscopes which they claim utilize the Coriolis effect (why hurricanes have the directions they do). You just tilt your wrist and the cursor moves. It’s quite sweet. I love it.

Anyway, frame of reference is why Einstein’s theory was so new – one if this many great discoveries was that the speed of light is constant in each frame of reference. Thus simultaneous events are not always simultaneous.

I’ll leave you with this question: suppose the sun were to suddenly disappear. Besides all humanity dying, the earth would obviously start going in a straight line tangent to its orbit. But tangent at what point? Where it was when the sun disappeared, or where it was 8 1/2 minutes later? The former is what Newtonian physics dictates, the latter is Eintsteinean.

Eh I’ve babbled for too long already – hope this was useful!

Anyone who took college level physics can probably recall that their prof probably joked about deriving the “meaning of life” from
F = ma
Force = mass * acceleration

This leads to an interesting observation: acceleration CANNOT be measured directly. It is always DERIVED from at least two other measurements, i.e. how fast (usually m/s) was the object going 1 time-unit (usually 1 second) ago and how fast is it going now, take the difference in speed and divide by the time unit ( m/s / s = m/s^2 ). Of course speed is derived from the measurement of the separation of two locations (distance) divided by the time required to travel between those to locations. Alternatively, force applied to an object can be measured and the mass of an object can be measured. A quick bit a algebra changes F=ma to F/m=a. So we take the force applied and divide by the mass of the object and get the amount of acceleration caused on the object.

What does all this mean? Diddly-squat!!! As Juliet said, “That which we call a rose/ By any other name would smell as sweet;” This is really cool and I look forward to seeing the interesting applications people come up with! :-)

Watch the Wii PC videos again; it’s because you get tilt control when it’s designed like this. When you tilt it, the other axes will show nonzero acceleration values. Outside of any gravity field, all sensors will read zero.