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[Jenn13]

f you wanted to shoot an arrow into space so that it never returns to the Earth, it must leave the bow at what speed?

 

Hide answer choices

[Entropian]

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Edited August 17, 2022 by Entropian
going through old posts

[JoeSchmuckatelli]

Spoiler

Faster than an unladen African Swallow

 

[Just Jim]

7 minutes ago, JoeSchmuckatelli said:

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Faster than an unladen African Swallow

 

 

Spoiler

I respectfully disagree... The African swallow is the stronger, clearly... But unladen the European swallow has less wind resistance...  
Now if they were both carrying coconuts it would be a completely different matter
(sorry... I couldn't resist)

 

Edited July 12, 2020 by Just Jim

[Vanamonde]

Joking replies aside, @Jenn13, this is how that question is answered. https://en.wikipedia.org/wiki/Escape_velocity

[wumpus]

On 7/13/2020 at 12:25 PM, Vanamonde said:

Joking replies aside, @Jenn13, this is how that question is answered. https://en.wikipedia.org/wiki/Escape_velocity

Depending on your values for "never", you need either Earth escape velocity or Solar escape velocity.  If you stick to Earth escape velocity, expect the arrow to return to Earth within 100s-1000s of years.  Solar escape velocity means there won't be an Earth if the arrow ever gets near the brown dwarf that used to be the Sun (and it almost certainly will be collected by some other star system before that).

File this under "things I didn't really understand before playing KSP".

[RCgothic]

Without atmosphere, about 11.1km/s.

 

With atmosphere most conceivable arrows would vaporise before making orbit.

 

Conceivably some sort of tungsten javelin could make it, but it's difficult to quantify the amount of drag.

Edited July 24, 2020 by RCgothic

[WestAir]

21 hours ago, wumpus said:

Depending on your values for "never", you need either Earth escape velocity or Solar escape velocity.  If you stick to Earth escape velocity, expect the arrow to return to Earth within 100s-1000s of years.  Solar escape velocity means there won't be an Earth if the arrow ever gets near the brown dwarf that used to be the Sun (and it almost certainly will be collected by some other star system before that).

File this under "things I didn't really understand before playing KSP".

Ok but what if I don't want it to return to what's left of the Solar System?

What's the Milky Way escape velocity?

[wumpus]

3 hours ago, WestAir said:

Ok but what if I don't want it to return to what's left of the Solar System?

What's the Milky Way escape velocity?

According to Vanamonde's wiki link, it is somewhere around ~500-600km/s (vs. ~11 for Ve Earth and ~16 for Ve Solar system).  But I think that number might be for in the dead center of the Milky Way, the way it is worded is odd.  Since the Milky Way isn't spherical, you'd have to do the calculations from original principles (following the footnotes in the wiki might be a good start).

[Codraroll]

While the question is legitimate and the answers interesting, I can't help but think there's something fishy about this thread. The thread title doesn't match the subject in the slightest, and it's created by a member whose only post in the forums is this one and who hasn't visited the forums since. I'm pretty sure the OP is a spambot, or at least a spam account, who failed at the link insertion stage but still got the thread posted anyway (or who plans to add those links later when the thread has slipped everyone's attention).

But hey, it might be the most constructive spam thread I've ever seen.

[Entropian]

If the spam is constructive, is it really spam?

[wumpus]

On 7/26/2020 at 3:01 PM, Codraroll said:

While the question is legitimate and the answers interesting, I can't help but think there's something fishy about this thread. The thread title doesn't match the subject in the slightest, and it's created by a member whose only post in the forums is this one and who hasn't visited the forums since. I'm pretty sure the OP is a spambot, or at least a spam account, who failed at the link insertion stage but still got the thread posted anyway (or who plans to add those links later when the thread has slipped everyone's attention).

But hey, it might be the most constructive spam thread I've ever seen.

I'd expect the odd homework question in any science fora, and this might be one.  Especially considering the easily googleable terms "escape velocity" weren't in the question.

[Codraroll]

11 hours ago, wumpus said:

I'd expect the odd homework question in any science fora, and this might be one.  Especially considering the easily googleable terms "escape velocity" weren't in the question.

Maybe, but I think a legitimate question wouldn't bungle up the thread title that much, and why is "hide answer choices" there?

[magnemoe]

On 7/27/2020 at 3:41 PM, Entropian said:

If the spam is constructive, is it really spam?

Can be, it was an spam mail going around, some guy claiming to be an time traveler trying to buy various futuristic technology with real sounding names like an Samsung D23-C superconducting storage coil.
No idea why might some wanted to troll the spammers, could also be to track who got this specific spam.