Are the effects of gravity and acceleration identical to the point that no sensor can tell the difference?

  • $\begingroup$ Gravity is a force, which causes object to accelerate towards the centre of the earth. Most sensors can’t intrinsically differentiate between this force and other external forces. But usually, the sensor is held from falling, and as such doesn’t feel the force of gravity $\endgroup$ – Jonathan R Swift Oct 12 '19 at 18:32
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    $\begingroup$ Einstein did not think they were different. $\endgroup$ – blacksmith37 Oct 12 '19 at 19:15
  • $\begingroup$ I don't think this qualifies as an answer but I don't have enough reputation to post a comment. The 'acceleration due to gravity' is a set constant (and that's 10 around these parts) but for this case it'd be 9.80665 meters per second squared. If you use an accelerometer then simply checking against that value will give you a good enough idea. There's also the obvious caveat of additional forces. If I throw a ball at the ground gravity doesn't account for the entirety of the balls acceleration and the accelerometer won't know the difference. $\endgroup$ – 小奥利奥 Oct 12 '19 at 20:44
  • $\begingroup$ Acceleration regarding to what reference system? A position sensor (GPS, laser, inductive, ...) can clearly tell you the acceleration value. A simple acceleration sensor cannot distingush betwee acceleration due to gravity and kinematic acceleration. $\endgroup$ – BerndGit May 7 at 12:33

Imagine an accelerometer that is in a box, and held aloft by a rope which is attached to a pulley, balanced by another box of equal mass.

You could either:

1) Cut the rope. The box will fall downwards, being accelerated by gravity.

2) Push the box downwards with an acceleration of $9.81m/s^2$, from an ‘applied force’

The accelerometer can not distinguish between these two scenarios.

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