jrb on August 06, 2009, 11:41:51 am
jrb:
    I'm going to have to disagree with you on the last point, that the assassin will go splat alright, but he won't realize it until it's too late.  Sheer instinct will tell him that he's traveling much too fast towards the ground and using his reaction gun as it shows he is he's starting to realize it.  The same way if you fall asleep at the wheel of a moving car and suddenly wake up and realize that your heading right for a tree and even hitting the breaks is not going to stop the car in time.

That's what I meant.  He has time to realize it before he dies, but by then it is far too late to do anything about it.

Sean Roach on August 06, 2009, 01:00:45 pm
That stark terror as he can literally see death approaching at 120mph.  Couldn't happen to a more appropriate character than a cold blooded killer.  Except perhaps his paymaster.

Edit.  I don't suppose they have the technology to go through what's left of his gray matter and map out some of his memories, do they?  Perhaps not.  Hopefully they'll get his PDA mostly intact.
« Last Edit: August 06, 2009, 01:06:02 pm by Sean Roach »

SandySandfort on August 06, 2009, 02:41:11 pm
Edit.  I don't suppose they have the technology to go through what's left of his gray matter and map out some of his memories, do they? 

Nope, he's brain soup.

Hopefully they'll get his PDA mostly intact.

Better than that.

NeitherRuleNorBeRuled on August 06, 2009, 02:46:16 pm
Hopefully they'll get his PDA mostly intact.

There's almost certainly some information in his vehicle; of course it is likely set up to destruct if not accessed "properly".  Then again, Tobi probably has better tech to get at it than the pink man's organization.

Jtuxyan on August 07, 2009, 03:11:28 am
The radius of LP is stated to be ~5km, while the radius of the earth is 6,378.1km. By the inverse square law, then, for our party to be experiencing 60% of earth gravity on the surface of LP, it must have 1/976,323th the mass of earth. This tells us that the mass of LP is ~6.11E18 kg. At less than 1/50,000th the size of the smallest planet, Mercury, it is also 1/150th the size of Ceres, the largest asteroid on record. With that in mind, it could conceivably have gone undetected for a considerable time, not being that gravitationally significant -- only it's density makes it special.

I still strongly disagree with all of the politics presented in this comic -- but I am left with no choice but to give it the science stamp of approval!

SCIENCE

Karadan on August 07, 2009, 10:16:03 am
Why? Because TLP's atmospheric density is approximately that of Earth's, and about 200 kph is the fastest a person can fall through that much atmosphere, irrespective of the strength of the gravity field.

Terminal velocity is the fastest an object can move through the atmosphere in free fall, and has nothing whatsoever to do with escape velocity.

Terminal velocity is affected by three things.  First, the density of the atmosphere, which in this case is presumed to be about the same as Earth's.  Second, the drag coefficent of the falling object.  Human is human, so his will be the same since he doesn't have a parachute.  And the final factor is the gravity by which the object is affected.  This is because gravity exerts a downward force on the object, while wind resistance exerts an upward force, which grows larger with velocity.  Thus if you have lower gravity and thus lower downward force, then you need a lower amount of wind resistance to equal that downward force, and thus you fall at a lower speed.

So you decrease the speed of an object in freefall by doing the following: increasing gas density, increase drag coefficient of the object, or decreasing gravity.  In this case the last one was achived, so he falls at a slower speed as I already stated.  A google search will tell you all of this in about 10 seconds.
« Last Edit: August 07, 2009, 11:20:05 am by Karadan »

SandySandfort on August 07, 2009, 10:27:28 am
.. I still strongly disagree with all of the politics presented in this comic -- but I am left with no choice but to give it the science stamp of approval!

SCIENCE

Well, I bet there are readers who see the science as a needless distraction from the politics. Oh well, that's why there are horse races.

Tell you what, if you are ready to reveal political flaws you believe you see, or better yet, offer some superior alternatives, I'm ready to discuss the issues. That is, until we get too far away from ELF and Scott pulls the plug on the discussion.   ;)

SandySandfort on August 07, 2009, 10:47:41 am
You obviously don't know much about terminal velocity. 

And you obviously don't know much about tact, diplomacy or simple good manners. However, I am a tolerant man and readily abide children fools.

Terminal velocity is the fastest an object can move through the atmosphere in free fall, and has nothing whatsoever to do with escape velocity.

OF COURSE it does. As I stated, escape velocity is the highest velocity an object in free fall can reach. Assume a body with an escape velocity of 1 kph. Care to guess what terminal velocity would be for a man free falling from 1000 kilometers though an atmosphere with pressure equal to earth's? Hint: it ain't 200 kilometers per hour.

Karadan on August 07, 2009, 11:36:28 am
Terminal velocity is the fastest an object can move through the atmosphere in free fall, and has nothing whatsoever to do with escape velocity.

OF COURSE it does. As I stated, escape velocity is the highest velocity an object in free fall can reach. Assume a body with an escape velocity of 1 kph. Care to guess what terminal velocity would be for a man free falling from 1000 kilometers though an atmosphere with pressure equal to earth's? Hint: it ain't 200 kilometers per hour.


I do apologize.  I realized how tactless that was after I posted it and changed it.

Escape velocity is the velocity that an object would need to reach in order to break out of the gravitational pull of another object.  For instance a rocket needs to reach escape velocity to get into outer space where it is not longer affected (significantly) by earth's gravity.  Terminal velocity is the highest velocity an object in free fall can reach.

Quote from: Wikipiedia link=http://en.wikipedia.org/wiki/Escape_velocity
In physics, escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy, as calculated by the equation,

    U_g = \frac{-Gm_1m_2}{r}

It is commonly described as the speed needed to "break free" from a gravitational field

And it really doesn't matter how high an object falls from as to what its terminal velocity is except in that the atmosphere is less dense the higher you go, and thus has a higher terminal velocity.  Thus if you assume that air resistance slows the decent to terminal velocity before the fall ends, it doesn't matter if you fall from 200 feet or 200 light years, the terminal velocity will be identical.

So yeah, I don't really care how massive an object is, or how high it falls from, terminal velocity will not change at a given altitude (on earth) provided that it has the same drag coefficient.  Now, it is possible to go faster than terminal velocity, and it is possible to go slower than terminal velocity.  Starting from a higher altitude means that at that high altitude your terminal velocity will be higher, so thus when dropping to a lower altitude it is possible to temporarily fall faster than terminal velocity.  It is of course also possible to fall a short enough distance that you never reach terminal velocity.  Neither of those things however change terminal velocity.

Quote from: Wikipedia link=http://en.wikipedia.org/wiki/Terminal_velocity
A free-falling object achieves its terminal velocity when the downward force of gravity (Fg) equals the upward force of drag (Fd). This causes the net force on the object to be zero, resulting in an acceleration of zero.[1]

This also shows quite clearly shows that the gravity that is affecting an object factors into its terminal velocity.

So yeah, if he is a human, and is falling in an atmosphere that is roughly the same as Earth's, and has 60% of Earth's gravity at its surface, he should hit the ground at roughly 60% of a human's terminal velocity on Earth, which is roughly 120 Kilometers per hour, as I already stated. Edit: Though I suppose I did so in m/s as that is my preferred method of velocity when dealing with physics.
« Last Edit: August 07, 2009, 11:50:29 am by Karadan »

SandySandfort on August 07, 2009, 03:45:13 pm
I do apologize.  I realized how tactless that was after I posted it and changed it.

Accepted and I in turn apologize for my snotty retort. <shake>

... So yeah, if he is a human, and is falling in an atmosphere that is roughly the same as Earth's, and has 60% of Earth's gravity at its surface, he should hit the ground at roughly 60% of a human's terminal velocity on Earth,

I understand what the Wikipedia article is saying, however, the falling body is still has a mass of (for example) 75 kilos. I still think that mass will continue to accelerate until it reaches escape velocity, hits the ground or until air resistance equals the inertial mass of those 75 kilos. But I'm not a physicist, I only play one on the internet. Assuming, arguendo, that he hits the ground doing 120 kph, though, the result is pretty much the same. In mountain climbing there is a saying that goes something like this, "after the first 50 feet, it's all academic."

Jtuxyan on August 07, 2009, 04:20:35 pm
.. I still strongly disagree with all of the politics presented in this comic -- but I am left with no choice but to give it the science stamp of approval!

SCIENCE

Well, I bet there are readers who see the science as a needless distraction from the politics. Oh well, that's why there are horse races.

Tell you what, if you are ready to reveal political flaws you believe you see, or better yet, offer some superior alternatives, I'm ready to discuss the issues. That is, until we get too far away from ELF and Scott pulls the plug on the discussion.   ;)

I fear such a discussion would not be productive. I'm a liberal who actually likes government and is pro-gun control and anti-religion. I think Escape from Terra is interesting, but it's as far from my beliefs as you can get.

SandySandfort on August 07, 2009, 05:20:29 pm
I fear such a discussion would not be productive. I'm a liberal who actually likes government and is pro-gun control and anti-religion. I think Escape from Terra is interesting, but it's as far from my beliefs as you can get.

Well see, we already have one belief in common.

Scott on August 09, 2009, 09:25:41 pm
Discuss away. If the topic drifts too far from EFT, I won't pull the plug but will move the discussion to the "Talk Amongst Yourselves" section and you can continue it there.

KBCraig on August 10, 2009, 12:46:48 am
I've always considered "escape velocity" to be a misnomer, and not because it's actually a speed instead of a velocity.

The speed necessary to escape gravity's pull is anything >0, given sufficient time and fuel. "Escape velocity" refers only to kinetic energy, not powered flight.


SandySandfort on August 10, 2009, 01:22:55 pm
I've always considered "escape velocity" to be a misnomer, and not because it's actually a speed instead of a velocity.

I am sensing what we lawyers call "a distinction without a difference." So I'll bite, my dictionary defines both speed and velocity as "distance traveled per unit time." Am I missing something here?