# Understanding voltage

I didn't miss it.
In case you didn't know, acceleration is not velocity. It is the rate of change of velocity.
If he has written v =Ldi/dt as opposed to f=Mdv/dt, he would have been
correct. but for a constant velocity, F=MA becomes 0 for ANY mechanical resistance. V=RI is not zero for constant current for any (non-zero) electrical resistance.
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Don Kelly snipped-for-privacy@shawcross.ca
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says...

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Then I would say that you were taught incorrectly or incompletely.

Put it this way- a mass at constant velocity (as seen at a boundary)
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Although this analogy is valid and can be worked out mathematically, it is the dual (in the circuit sense) of the analogy that is usually used.
Mechanical Electrical Force Voltage Speed Current Mass Inductance Compliance Capacitance Windage Resistance Sliding friction is very different
This is the scheme used mostly by Olson. some of the analogous equations are: f=ma v=L(di/dt) P=fs P=ei s is used for speed KE=m*s^2/2 KE=L*i^2/2 magentic energy in an inductor.
This also leads to one of the most useful analogies that I have used--impedance, especially characteristic impedance. For ac quantities. Mechanical impedance = f/s and and Z=v/i. This concept is good for levers, loudspeakers, gearboxes, transformers, etc.
Bill
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-------------------- Looking at it from a machines viewpoint, the nodal analogy is, in my mind, having used both, actually better than the loop analogy. force----current voltage----velocity capacitance-----mass inductance----spring compliance conductance----resistance
Note that for gears the speed is proportional to the gear ratio and the torque is inversely proportional which corresponds to voltage and current respectively for a transformer. This is true for a lever as well. These are inverted in the loop analog but the impedance, as you note, is inverted in the nodal analog. In a motor the torque is current dependent and the voltage is related to speed. One also notes that the inertial mass of a spinning armature nicely reflects back to the electrical side as a capacitor. This analogue also more closely matches the mechanical block diagrams for multimass cases and in such cases, the nodal approach does offer some computational advantage (just as in a power system load flow or even fault analysis a nodal approach is used- simpler in that there is no need to choose loops and node choice is automatic- an admittance array is a turn the crank algorithm with no "choosing" of a base tree and branches so it is much easier to program the idiot box).
Berenak in "Acoustics" introduces both models but tends to the loop or impedance model but others in this area have used the nodal or mobility model.
What it boils down to is that the choice is really the user's preference (and such preferences are based on what one's background happens to be ).
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Don Kelly snipped-for-privacy@shawcross.ca
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Howard Hughes proved that liquids are compressible.
Then, we all called him a genius, which he was.
Then, he crashed his toy (or it was sabotaged). Then, he went nuts.
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On Fri, 03 Oct 2008 01:10:59 -0700, RoyLFuchs

Right. Prior to that, nobody noticed that sound propagates in water.

C'mon Roy, explain voltage to us.
John
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snipped-for-privacy@highNOTlandTHIStechnologyPART.com says...

s/Roy/Dimbulb/
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Keith

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On Fri, 03 Oct 2008 08:25:45 -0700, John Larkin

It also propagates through solids, idiot. Sound propagation has nothing to do with compressibility.

Take a small rooftop lightning rod, and an ankle chain. Walk up on a tall 14k' plus mountain.. Hold the lightning rod up.
You'll learn what voltage and current is, but it will be the last thing you learn.
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snipped-for-privacy@urfargingicehole.org says...

Really Dimbulb? How does sound work in your universe?

You oughtta try it sometime, AlwaysWrong.
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Keith

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On Fri, 03 Oct 2008 16:11:13 -0700, RoyLFuchs

Wonderful! You are raising being really, really wrong to a high art.
Here, this may help:
http://en.wikipedia.org/wiki/Speed_of_sound#General_formulae
http://hyperphysics.phy-astr.gsu.edu/Hbase/sound/souspe2.html
See? The speed is inverse on compressibility. That was known a long time before HH was born.

You don't understand voltage, do you? Don't feel bad, lots of techs don't actually understand voltage. I suppose I'll have to explain it one of these days.
John
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John Larkin wrote:

You'll have to use small words and type real slow, for dimbulb.
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aioe.org, Goggle Groups, and Web TV users must request to be white
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On Fri, 03 Oct 2008 19:37:20 -0700, John Larkin

Wrong. You speak of liquids and gasses. In solids it relates to shear deformation at the lattice level. Nothing is compressed. No physical shape change occurs
In the wiki link, you should examine the portion on speed through solids, as most of the article is about speed through, and effects on gasses and liquids. Solids barely get a mention.
You probably believe that glass is a solid, and you probably think that two colliding spheres is only a momentary collision.
You should study billiards. Though the balls appear solid, they are quite elastic. Ceramic billiard balls (or other more brittle medium)would force players to re-learn everything they previously thought they knew about "English".
It is not a direct collision/vector response. The rotation of the primary moving ball at the impact point imparts some of that rotation into the ball that gets collided with. That proves that the contact is slightly more than momentary, and that friction comes into play.
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On Fri, 03 Oct 2008 19:37:20 -0700, John Larkin

Likely far more than you do or ever will.

You're an idiot, Larkin. Don't feel bad though. Dopey asswipes like you die alone, much like OJ will.
I suppose you should go back to the fuck off and die barrel, asswipe.
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One reason to know something about electricity, that many EE's might not know, is to understand corrosion and cathodic protection. A few years ago, I saw a railroad bridge that was so rusted out that it would have scared the hell out of me if I had to ride over it. Similar problems exist in highway bridges. It really becomes scary when you think of what improper protection of rebar could do.
Bill
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True... but that is not inherent to bridge building. Bridge building is about choosing the right materials and dealing with the forces which has nothing to do with electricity. Although your point shows that what I said is not completely true.
I'm not saying electricity is useless and I'd rather everyone know much as they can about everything... but if you gotta choose to split of your time or not then it's usually best to not.
Although usually learning the basics doesn't take that long. My point wasn't about learning electricity but about roses statement that implied the guy couldn't build a good bridge if he didn't know about it... which is ridiculous.
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So are you trying to say that learning about electricity is not a wise use of time?
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So are you trying to say that learning about electricity is not a wise use of time?
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Of course not... But that you seem to imply that if he doesn't know
electricity that he can't build a good bridge which makes no sense.
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Bridges are civil engineering aren't they?
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Bye.
Jasen
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Some are rocks--like the Wheatstone Bridge.
Bill
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Private Profit; Public Poop! Avoid collateral windfall!

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You're un-civil.
Well, your post was un-civil engineering, anyway. :-)