[TML] Thrust Distribution Field

[Garry Ward]

----- Original Message ----- 
From: "Craig Berry" <cberry at cine.net>
To: <tml at travellercentral.com>
Sent: Friday, August 03, 2007 3:51 PM
Subject: Re: [TML] Thrust Distribution Field


>> Date: Wed, 01 Aug 2007 17:12:24 -0700
>> From: Anthony Jackson <ajackson at iii.com>
>>
>> > It's worse than that; the needed energy depends on how fast you're
>> > going relative to a particular observer, or vice versa.
>>
>> No, it really doesn't. As long as you're pushing on something, the total
>> energy requirement is constant, though where the energy winds up varies
>> depending on reference frame.
>
> Yes, it really does. :>  Let's assume you're looking at such a "remote
> push" ship from a frame in which both the ship is moving at 10m/s
> relative to the mass it plans to push on.  Make the ship mass 10kg and
> the pushed-on reaction mass 1kg, as in my previous example.  The ship
> will accelerate by 1m/s, again as before.
>
> First, analyze this in the initial rest frame of the pushed body.  The
> initial kinetic energy of the system is then all in the ship, and is
> 0.5(10kg)(10m/s)^2 = 500J.  The final KE, with the reaction mass now
> moving 10m/s and the ship 11m/s, is 0.5(1kg)(10m/s)^2 +
> 0.5(10kg)(11m/s)^2 = 50J + 605J = 655J.  The change in KE is thus
> 155J.
>
> Now, start in the pre-acceleration rest frame of the ship.  The
> initial KE is all in the reaction mass: 0.5(1kg)(10m/s)^2 = 50J.  The
> final KE, with the reaction mass moving 11m/s and the ship 1m/s, is
> 0.5(1kg)(11m/s)^2 + 0.5(10kg)(1m/s)^2 = 60.5J + 50J = 110.5J  The
> change in KE is thus 60.5J.
>
> Again, the same maneuver takes different amounts of energy depending
> on the frame in which it's being observed, which breaks physics.
>
Yeah, I tend to have Heretical tendancies (I am Lutheran, after all), but 
again, this frame of reference idea that I've seen used in a wide variety of 
places (not just here) sounds more and more like the ancient Greek 
philosophers arguing about why you can't walk through a door because the 
distance between you and the door can always be cut in half.

But then, I also think that multiplication and division by zero should be 
treated the same as multiplcation and division by 1.

Garry
> -- 
> Craig Berry - http://www.cine.net/~cberry/
> "The road of excess leads to the palace of wisdom." - William Blake
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