[Phys-L] Re: thrown ball with air drag

[Carl Mungan <mungan@USNA.EDU>]

> You can say that
>
> 1/v^2 = 1/v0^2 +1/vT^2
>
> can be graphically represented by a right triangle. But the same is
> true for the thin lens formula or for two parallel resistors. It is not
> at all obvious that such common property is indication of something
> significant. Ludwik Kowalski

The thin-lens and parallel-resistor formulas are sums of reciprocals
(not squared) and can be easily understood by interpreting the
inverses physically:

* in the parallel-resistor case, the reciprocal of resistance is
conductance so that rule just boils down to sum of conductances

* in the case of thin lenses stacked against each other, the
reciprocal of focal length is focal power and we again can interpret
the sum that way

But what is inverse kinetic energy (to use the sum idea) or inverse
velocity (to use your idea of a right triangle)? Nothing physical
that I can think of. Carl
--
Carl E. Mungan, Asst Prof of Physics  410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-5002
mailto:mungan@usna.edu     http://usna.edu/Users/physics/mungan/
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