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I am receiving unknown units of speed from another system. I must divide the value by 32 to get meters per second. What units do I use to refer to the values I'm receiving? Is there any such unit? Is this just random malice from the previous developers? Google give me nothing.

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It sounds like someone got a meters to feet conversion backwards. 10 meters is about 32.8 feet. Also, are you getting meters per second (velocity) or meters per second squared (acceleration)? 1 g is about 9.8 meters/(sec*sec) or 32.1 feet/(sec*sec). Another context where 32 shows up is in atmospheres of pressure. You get about 1 atmosphere of pressure for a water column 32 feet deep. Context would help a lot in guessing why 32 is showing up. –  Benjamin Franz Apr 10 '12 at 21:07
    
Excellent observation. Given the system, it would not surprise me to find someone got a conversion backwards and someone else had to compensate for it. –  Dave Apr 10 '12 at 21:50
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The unit is known as one semisemisemisemisemimeter-per-second, or SSSSSMPS for short. With the accuracy of 2.5%, it is also one decifeet per second, dft/s, or one inch-per-second-with-26%-tax-included, or 1 IRSinps for short. –  Luboš Motl Apr 11 '12 at 6:22

2 Answers 2

up vote 6 down vote accepted

Given that if you divide your numbers by 32, you get a speed in meters per second, that means that the unit for the speeds you are being given is $\frac{1}{32}\mathrm{\frac{m}{s}}$. There's no standard name for this unit, but that's not a problem. People use unnamed, nonstandard units all the time. In fact, that's how all our current units got started. A meter was originally defined to be a pretty much arbitrary distance, and the only reason it now has a name and is so widely used is that a bunch of people all agreed to call this particular arbitrary distance a "meter."

If it bothers you to be using a unit without a name, you can give it one. Just make a note somewhere that, say

$$1\text{ Dave} = \frac{1}{32}\mathrm{\frac{m}{s}}$$

and then you can write that your speeds are measured in Daves.

Here's another post on the nature of units that is, if not directly relevant to you, at least closely related.

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Thanks much. +1 for naming a unit after me. –  Dave Apr 10 '12 at 21:51
    
Also, thanks for the title edit. Much better than what I used. –  Dave Apr 10 '12 at 21:55

Dividing by 32 is equivalent to shifting by 5 bits in binary. This number probably comes from some digital hardware which uses a fixed point binary representation for the velocity.

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Yes, that is what's happening. I was just wondering why and what to call it. Thank you. –  Dave Apr 10 '12 at 22:09

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