Timeline for Accelerometer validation trace
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 11, 2015 at 15:49 | comment | added | Hypnosifl | (Of course, you could also use a purely Newtonian analysis to show that simple devices like a strain gauge or a weight on a spring will deviate from their relaxed state when held vertically in a gravitational field--but that's just another way of showing that these devices do not measure 'coordinate acceleration in a Newtonian frame', even from a Newtonian perspective) | |
| Jan 11, 2015 at 15:26 | comment | added | Hypnosifl | @Carl Witthoft - You don't need GR in the design of accelerometers, but that wasn't my point--my point was just the conceptual one that any basic physical device for measuring acceleration like a strain gauge is going to be measuring proper acceleration, not coordinate acceleration in a Newtonian frame. Do you disagree? | |
| Jan 11, 2015 at 15:01 | comment | added | Carl Witthoft | @Hypnosifl you're going into the ozone there. Accelerometers in everyday use are just strain gauges and there's no need for GR. RLY! | |
| Jan 11, 2015 at 14:43 | comment | added | Hypnosifl | (continued) According to general relativity, gravity is not really a "force" at all but rather curvature of spacetime, and general relativity's equivalence principle says that being in freefall in a gravitational field is locally equivalent to moving inertially (zero proper acceleration) in non-curved spacetime, and likewise sitting at a constant radius in a gravitational field is locally equivalent to accelerating in non-curved spacetime (so that's when an accelerometer should measure a nonzero proper acceleration). | |
| Jan 11, 2015 at 14:40 | comment | added | Hypnosifl | @Carl Witthoft - But accelerometers don't measure acceleration relative to a Newtonian inertial frame, nor do they measure net Newtonian "force"--they are real-world devices and hence they are better understood using general relativity which is more accurate than Newtonian gravity. In general relativity, the only frame-invariant notion of acceleration is proper acceleration, and since accelerometers don't make use of any particular reference frame, naturally that's what they measure. | |
| Jun 17, 2014 at 0:05 | comment | added | branny12000 | Hey guys as I have already acquired a trace from this method any ideas of how to work out error? And align the traces so they can be compared? | |
| Jun 16, 2014 at 15:11 | comment | added | branny12000 | Ah I see! Thank you guys for helping me. Well I have considered just a simple drop experiment but the test has already been done by another person and I just must analyse the result | |
| Jun 16, 2014 at 14:48 | comment | added | Carl Witthoft | To clarify (maybe :-) ), $g$ is a force . Acceleration is a change in velocity which only happens when there's a net force. your accelerometer's net force in the $\hat{z}$ direction is zero due to the normal force of the surface it's sitting on. | |
| Jun 16, 2014 at 14:38 | history | answered | YungHummmma | CC BY-SA 3.0 |