Does anyone on this list know how speed/acceleration work in relation to
required energy/mass? Theres something Im not understanding. Heres a
sample situation:
A 100 tonne starship comes into existence in deep space (how it got there
is irrelevant). It has unlimited fuel and can accelerate at whatever Gs
its captain wants without harm to the captain (who is the only person on
board). The captain accelerates the ship at 1 G in a particular direction
(which direction is not important).
Now, the energy needed for the ship to remain motionless is nothing at
all, right?
The energy needed for the ship to accelerate, measured in tones of thrust,
is 10 tonnes of thrust per 1 G of acceleration per tonne of ship = 1,000
tonnes of thrust, right?
Okay, lets say the ship accelerates up to a certain speed; say 1,000 km
per hour (it doesnt really matter). How much energy is required to
remain at that speed? I would assume none as the ship would simply be
drifting. (Im not concerned at all about the resistance of the particles
in space, and the ship is far enough away from all bodies of gravity that
it doesnt have to worry about that.)
Now, if the captain wanted to start accelerating again at 1 G, how much
thrust will he need? It will be 1,000 tonnes of thrust again, right? If
so, 1G of acceleration should require the same amount of thrust, no matter
what speed the ship is initially traveling at.
Am I right or wrong so far? Are my assumptions correct?
Now for something slightly different. Einstein said that the force of
gravity was the same force as that which you notice when you accelerate.
So, if thats true, the ship will never actually *not* be near a source of
gravity as long as it is accelerating, because if it is accelerating it
*is* a source of gravity. This gravity, however, would only be present
when accelerating, and not when drifting, would it not?
Okay, assuming Im correct so far, apparently things start to change (or,
at least become noticeable) when you begin to approach the speed of light.
Wait. The *speed* of light? Hmmmm. No, Im going to ignore that thought
for now.
So the ship is getting speedier and measurements are starting to change.
Apparently this is because energy equals mass (with the numbers depending
on how you measure it). The faster you go, the more mass you have. No no
no, that cant be right. Going a certain speed does not require any
energy at all. Only accelerating up to that speed requires energy.
Right?
This should mean that if the ship accelerated to near-light speeds, and
then stopped accelerating and coasted at that speed for a while, while it
is just coasting time is behaving normally (due to there not being any
gravity well when coasting) and the ships mass is 100 tonnes because its
not using any energy to accelerate.
So, if this ship was coasting at such a speed that, if it started to
accelerate its mass would double, is this change in mass instant?
I think one of my assumptions may be wrong, but I dont know what one.
Can anyone help?
- Daryl