If it is possible to walk to the space station (see
http://answers.google.com/answers/threadview?id=364664), isn't that
against the idea of escape velocity? (see
http://answers.google.com/answers/threadview?id=364717)

Please kindly explain how these two ideas can be congruent, or not.

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Request for Question Clarification by justaskscott-ga on 22 Jun 2004 22:04 PDT

In the case of walking to orbit, you don't need any particular
velocity -- you'd just take it one step at a time, as quickly or
slowly as you desire.  There are no steps if you are trying to rocket
straight up from the earth's surface into space.   It's like comparing
a person climbs Mount Everest and a person who catapults himself to
the top -- there's a big difference between the two situations.

I don't know the technical terms for my explanation.  Yet I feel
confident that my explanation is correct.

Is this a sufficient answer?  If so, I'd be happy to post it as an answer.

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Clarification of Question by crythias-ga on 23 Jun 2004 06:19 PDT

Well, what I was thinking about was more regarding geosynchronous
orbit rather than the orbit of the space station (it was very late
when I wrote the question) so I understand that the space station is
moving too fast. The thing that I couldn't resolve in my head is why a
slow and steady (in a certain viewpoint) motion couldn't overcome
gravity. What I realize after reading knowledgeisnotpower-ga's comment
is that the angular velocity of the earth's spin is constantly
attributed to the person on the ladder by the nature of the ladder
itself moving with the earth. A person travelling up a ladder (or an
elevator) isn't violating the escape velocity (which is a vector, not
just "speed") of the earth because the rotational part of the vector
is very significant.

I think that would have been a better answer in line with what I'm
asking, if I've condensed it properly.

crythias-ga:

The two concepts are congruent; escape velocity is the speed you need
to be travelling at so that the gravitation pull of the planet is no
longer strong enough to pull you closer to the planet as you travel
parallel to the surface (ie. orbit). Gravity pulls you towards the
surface, but you are travelling fast enough such that the path you
travel is at least equal to the curvature of the surface.

If you had a staircase to climb, however, then the stairs provide all
the support you need to overcome the force of gravity (otherwise you'd
fall through the stairs!). So, no need to get up to an escape velocity
first.

An interesting thing to point out in this unscientific comment is
that, by the time you reach the top of the staircase, you will be
travelling at the necessary velocity (relative to a fixed point in
space) to achieve a geosynchronous orbit. The challenge in building
the staircase is that the staircase must travel through the Earth's
atmosphere to get from the surface to space. The atmosphere tends to
have a lot of movement internally; this movement will apply lateral
and shear loads on the staircase, enough to snap it into many pieces
unless it were strong enough to withstand all of the buffeting. Modern
materials and engineering are not up to this challenge yet.

the correct answer is that we orbit stuff very high, but just being
high doesn't put you in orbit.

you're in orbit, not when you move UP, when you move SIDEWAYS,
parallell to the ground really, really fast (the lower you are, the
faster you have to go).

You might notice that the space shuttle launches straight UP to clear
it's launch tower, but it immediately starts leaning over more and
more sideways. Well, that's why.  When it gets to teh space station,
it's moving completely sideways and not moving up at all.

The reason we put stuff in orbit really high up (like 100 miles) is
that anything orbiting lower would push (sideways) against the air,
which would slow it like a parachute. Then it would  just fall to the
ground.

And in fact, that's exactly what happens when the space shuttle comes
home.  It drops down low enough to hit the air, which slows it down. 
In fact the shuttle pushes against the air so hard that it can (and
did once) tear the shuttle apart.

On the moon, with no air, you can orbit as low as you want, and that's
just what they did in the apollo space program.

They orbited the moon several miles up because they didn't want to run
into any mountains, but if you had a planet that is perfectly smooth,
like a crystal ball or a billiard ball, you could orbit the planet
inches from the surface.

Something orbiting is actually just falling down, along a curved path,
exactly like a baseball.  But it's  moving sideways so fast that the
curve of the earth matches the curve of it's path, and it moves in a
circle.  Things in orbit are actually falling toward earth forever but
stay at the same height!

Interestingly (maybe), stuff doesn't orbit the earth really, it orbits
the center of the earth.  You can't get closer to the center than
8,000 miles because you'll bump into the ground.  In that sense, all
orbits are at least 8,000 miles high!

I'm too tired from typing to address the geosync orbit.  The answer is
that you can't take the stairs to teh space station because it's
moving sideways WAY to fast.   But theoretically, you COULD walk to a
communications sattelite.

Remember when I said that the higher you go, the slower you need to
move sideways to stay orbiting?  Well at 22,300 miles high, that orbit
speed is exactly the same speed as the surface of the earth moving
(1,000 MPH).

It doesn't feel like you;re moving 1,000 MPH now, does it?  But you
are.  The earth is turning around and around (that's what causes day
and night), and it's surface (and you) move sideways at 1,000 MOH. 
You don't notice it because everything around you is moving at that
exact same speed.

As I understand it, the primary question is whether the concept of
walking to a very high point (thus escaping from Earth's gravity) is
in conflict with the idea of needing a large initial velocity (escape
velocity) to achieve the same height.  Basically, the difference
between the two cases is whether all the force is exerted at the
beginning (launching the object) or is exerted gradually (by walking).
 Here is a physics-based explanation.

Escape velocity is the initial velocity needed (at the time of launch)
to escape from the Earth's gravity.  If the only force acting on the
object after launch is gravity, we can use conservation of energy to
understand this.  At the beginning, the object has kinetic energy, the
energy of motion.  As the object ascends, kinetic energy is converted
to potential energy.  The object slows down, but it gains stored
potential energy.  (The potential energy can be recovered by dropping
the object from a height--you will see it accelerate as potential
energy is converted back to kinetic.)  Escape velocity is the minimum
initial velocity needed so that when the object escapes the Earth's
gravity, all the kinetic energy will be converted to potential energy
with none left over.

In the case of walking to orbit, the forces are not exerted all at the
beginning to launch the object.  Instead, the object (or person)
exerts forces at each step.  In physics terminology, the object is
doing work against the force of gravity.  The work done increases the
potential energy of the object, elevating it to greater heights.

Maybe this explanation will help you understand what's going on.  If
not, at least I'm not getting paid for this.  :)

I think it should also be noted that at each rung of a ladder
situation, each step the ladder pushes up against the force of the
person pushing down. At this point, there would be no "escape"
velocity because nothing really escapes, if I understand it correctly.

Ok, well thanks so much for the information. I think that the comments
are sufficient at this time. :)