Re: Falling up

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?

Sure as you ascend T.V. will increase as the air thins but would it be
enough or would you end up hovering at some fixed distance?

The thing to remember is that something like a rocket engine is doing the same thing as reversed gravity. It may take longer to "escape", but much like there are different ways to enter earth's atmosphere and the time it takes to reach ground there are different ways to reach space. I think the 10,000 meters figure was based on the fact that a rocket has a very short period of time to move the capsule fast enough to coast the remaining distance.
.

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