Re: 40MHz Spark Gap Behavior (fwd)
---------- Forwarded message ----------
Date: Tue, 21 Apr 1998 10:48:24 -0600
From: Bill Lemieux <gomez-at-netherworld-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: 40MHz Spark Gap Behavior
I hope I don't sound like I'm picking nits, but if you're going to
explain things, at least use your terminology correctly, or you'll
only confuse people further. to wit:
> Isn't it true that power is determined by Watt-seconds, or Joules? If I
> look at a discharge of anything, I'm going to see Watts-per-unit-time.
> Therefore, if one Watt, in one second equals 1 Joule, then 1 Watt in 1/2
> second =
> 1/0.5 = 2 Joules. 1 Watt in 1/4 second = 1/0.25 = 4 Joules, etc.
Good illustrative discourse, so far. But then you go astray...
> Look at it like a rifle bullet. Assume that a given amount of gunpowder
> will produce a given amount of explosive force.
Um, not quite. FORCE=MASS*ACCELERATION, whether it be expanding gasses
or baseballs. In this case, stored energy is released over either a
period of time (slow burning black powder for example) or a short period
of time (fast-burning nitrate powders).
> Cause the gunpowder to burn
> slowly, and all the force
You mean energy, not force. The force applied to the bullet derives
how quickly the energy is released, see your own (correct) explanation
> will be expended over a great amount of time, and
> may never even build enough pressure to move the bullet to end of the rifle
> barrel. On the other hand, the same amount of force,
Nope, the _force_ on the bullet is greater over a shorter period of
the total amount of energy stored in the gunpowder is the same.
Also note that your explanation falls down in that the powder burns
_because_ it is confined, and that any time you actually get the powder
the bullet _will_ move in a very spritely manner toward the muzzle
has been jammed in some spectacularly secure fashion, in which case the
gets to eat parts of the breech. But never mind all that...
> expended in a
> microsecond, can propel the bullet so fast that simple air friction can
> turn the slug molten in flight.
That's one hell of a firearm. Melting projectiles with air friction is
in the regime of railguns. The highest velocity cannon on the planet,
Israeli Mercava system with a muzzle velocity approaching 3000 MPS,
melt its projectiles in flight...
> Same amount of energy, same amount of
> force, much different levels of power :)
No. The force is NOT the same. If it were, the gun would violate F=MA.
If the force were the same, the acceleration would be the same.
> And how about your capacitors? If you bleed the energy off slowly through a
> resistance, you could literally power a DC motor for a while. Discharge the
> same energy all at once, and you can explode a motor in an instant ;) Same
> levels of energy, but greatly different amounts of power. :)
True, and agreed. Just wanted to clarify where you misspoke.
. personal email: gomez-at-netherworld-dot-com .
. personal web page: http://www-dot-netherworld-dot-com/~gomez .