Re: Some propellantless propulsion fun


"The Ghost In The Machine" <ewill@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:fnvml5-7q2.ln1@xxxxxxxxxxxxxxxxxxxxxxxxxx
| In sci.physics, Spaceman
| <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx>
| wrote
| on Thu, 24 Jul 2008 14:09:17 -0400
| <_LCdnet_rcPPWBXVnZ2dnUVZ_uGdnZ2d@xxxxxxxxxxx>:
| > The Ghost In The Machine wrote:
| >> In sci.physics, Spaceman
| >> <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx>
| >> wrote
| >> on Wed, 23 Jul 2008 01:53:28 -0400
| >> <_t2dnYoSQanBWhvVnZ2dnUVZ_u6dnZ2d@xxxxxxxxxxx>:
| >>> The Ghost In The Machine wrote:
| >>>> I'm not sure what you mean by "10 cubic yards"; I'll assume
| >>>> a box 10m x 1m x 1m, with the ball shot longway through
| >>>> the box. Besides, a yard is approximately a meter anyway.
| >>>
| >>> Well,
| >>> that is not what I actually meant but good enough since you used
| >>> it instead of being an ass about the way it was stated.
| >>
| >> You said "10 cubic yards". That is not quite sufficient to determine
| >> the dimensions of the box. I made an assumption and ran with it.
| >>
| >>>
| >>> <snipped an actual answer from someone that is not a full ***>
| >>> Ghost is actually "sometimes" someone that does try and enlighten
| >>> people without putting himself on the highhorse while he does such.
| >>>
| >>> Thanks Ghost.
| >>> But the ball in the box horse is dead already.
| >>> :)
| >>>
| >>> So,
| >>> Do you want to take on the problem with the friction involved
| >>> in the original post?
| >>> :)
| >>>
| >>
| >> And why would friction make a difference? All that does
| >> is adjust the acceleration. If you want I can try to
| >> go into calculus with a variable acceleration function, but
| >> it wouldn't make any difference.
| >
| > Friction slows the acceleration or velocity rate.
| > Just as it does on Earth to allow such propellantless
| > propulsion to occur on the ground.
| >:)
|
| And what example of propellantless propulsion are you referring to?
|
| If I start to walk at 1 m/s (relative to an absolute
| coordinate system attached to the Earth), and weigh 100 kg,
| the Earth (weighing 5.976 * 10^24 kg) has to move
| 1.6734 * 10^-23 m/s to compensate. Not many people will
| be able to measure that value (the width of a proton is on the
| order of maybe 10^-14 m).
|
| As Androcles correctly points out, I therefore am walking
| 1.000000000000000000000016374 m/s with respect to the
| Earth, assuming Newtonian mathematics.


Err..
1.000000000000000000000016374
+/- 0.0000000000000000000000000005 m/s
(or +/- 10.0 m/s within the limits of experimental accuracy,
assuming Einsteinian mathemagics)

| But momentum is still conserved. (It gets more complicated
| if one throws angular momentum into the mix, though that's
| conserved, too.)

Well, yeah, unless you are walking up, possibly a ladder.
I doubt Spaceman is waking up.


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