Re: Falling up

On Mon, 17 Nov 2008 07:27:05 -0600, All hail Discordia < > wrote:

On 15 Nov 2008 17:09:28 GMT, raven@xxxxxxxxxxxxxxx (Raven-Poe) wrote:

mike <mikespam@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

I don't have 4e but I took the OPs Q as meaning that it is gravity that is
being altered, not mass or anything else. It's magic, so anything can be
possible, but sticking to gravity and assuming physics is still constant,
the answer is what I supplied.


John

Hi,
I know I?m not the brightest of buttons, but I?ve a trivial question
to add here.

Gravity decreases rapidly with increased distance, so would the
falling subject actually slow - since the Earth is apparently the
source of this force?

Umm, while gravity doies drop off with distance, on the scales we're
talking about, I' wouldn't call it "rapidly". But yes, if you were using
this as a source of propulsion for a space ship, then it would fall off
with distance: the further you got away from the earth (or orther
dominating mass that is providing your local gavity feild) the lower the
force tending to acceleerate you. However, the loss of force from gravity
won't cause you to stop: if you could keep the effect up long enough and
aimed at the moon, by the time you got to the point where there was no
force due to gravity becuase the moon and the earth's grivty balance,
you'd have build up a very respectable speed. Then you could turn off the
effect and allow the moons gravity to pull you in.

Of course, *stopping* will be pretty tough. :)

Probably trivial with minor distances involved in this case, but I?m
curious as to what you'd rule.*

mik :-)

*In case someone makes a ?space capsule? and tries to use this power
to visit the moon.

It's early in the morning and I need a shower, so I'm not going to do the
math, but I'd look up earth escape velocity, and figure out how long the
capsule would have to fall to get to that speed and see if they reach that
speed before the effects of gravity reduce significantly, which is my gut
level feeling as to how it'd go. I'd also make them consider problems of
astrogation and lateral thrust (as this sort of contragravity only provide
forces in line with the local gravity feild: basicly, it only lets you go
up and down).

Of course, if they pushed it, I'd launch them into some sort of edgar rice
burroughs adventure, where they'd ultimately have to solve these problems
to get -back- after they ended up on some strange new world instead of the
moon... :)


John

Feel free to correct me, but a object falling up at any G will hit its
terminal velocity long before it hits the approximate 10,000 meters
per second required to escape earths gravity would it not?


It isn't necessary to hit that speed to escape earth's gravity. Escape
velocity is merely the speed at which you need apply no further
acceleration in order to escape. If you have unlimited "fuel" so you
don't have to shut off your "engine" you can fly to the moon as long
as you have enough thrust to get off the ground at all.
.

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