Text 28598, 68 rader
Skriven 2007-05-05 05:21:00 av Jeff Binkley (1:226/600)
     Kommentar till en text av Bob Ackley
Ärende: Muslems
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BA> A>>> VH>And explain how we can cross interstellar space?

BA> TA>> Given the fortitude and acumen displayed by our African
BA> TA>> ancestors travelling from Africa to the Middle-East and Europe
BA> TA>> in their time, I think we can master interstellar space to our
BA> TA>> next new habitant in our time.

BA> VH> I just asked this question of John.  We want to go to a planet
BA> VH> that is 10 light years away.  At an accleration of 1G, how long
BA> VH> will it take us to get there?

BA>Couple of centuries, most likely.  Note that you can't accelerate the
BA>whole way, at the halfway point you have to start decelerating,
BA>presumably at the rate of 1G.

I posted this a couple of days ago:

Actually it isn't as difficult as you are making it.  If you assume that
your braking deceleration is the same as your acceleration then you
simply divide the distance by half to calculate the midway point of
acceleration.  Once you have the answer then you multiply by 2 to get
the total time.  Mass and thrust are irrelevant because Vern said
acceleration was constant.  Of course where does the force of 1G
acceleration come from ?  Well Vern will have to let us know that trick.

Now the issue here is the speed of light.  If we assume Einstein is
right then the question becomes how quickly do we reach the speed of
light under 1G acceleration and then we will go the speed of light the
rest of the way to the midpoint, unless we can't reach the speed of
light by the midpoint.

The acceleration rate of 1G (using earth as the reference for G) is 9.8
m/s^2.  Easier to round to 10 m/s^2 .  The speed of light is 300,000
km/s .  Without using Calculus the formula for acceleration in Physics
is:

v = v0 + at

v0 is initial velocity
a is acceleration
t is is time
v is current velocity
in this case we are starting from rest so v0 = 0 .  Thus the time it
takes to get to the speed of light becomes:

300,000,000 m/s = 10 m/s^2 * t

or 30 million seconds which or just over 347 days.  So at that point we
will travel at the speed of light until 347 days before arrival and then
we start braking.

We haven't solved for X yet to determine the distance traveled in the
347 days on either end of the trip.  I'll leave that for anyone
interested in going further with this.


==========================

The answer is somewhere between 11 and 12 years.  If someone is 
interested I'll do the mth to get th exact number.


Jeff



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