What goes up must come down

Tell stories about your spud cannon adventures!

Postby fullmetaljacket » Sun Jan 15, 2006 1:27 am

While the spuds are in flight, the earth is still turning, so technically if fired stayed up they can't land in the same place....
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Postby orangekid13 » Sun Jan 15, 2006 5:54 am

not true... objects in motion tend to stay in motion
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Postby SMOMW » Sun Jan 15, 2006 9:14 am

fullmetaljacket, go and try to jump as high as you can, did you land in the same place or did you move opposite the earth's movement and land a few feet away?

when something leaves the earth and goes up it is still rotating with the earth in relation to space.
the reason our projectiles don't fall directly back down is beacause of wind, air resistance, and other factors (like slight angles from NOT shootind directly at 90deg to the earth's core) are at play.

at least I think

but of course we are now horribly offtopic! oh no!
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Postby TakerLabs » Sun Jan 15, 2006 9:27 am

Well, with all due respect, it is cacophobia91 story and he can tell it how ever he chooses.:)
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Postby c0mpl3x » Sun Jan 15, 2006 2:41 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mr.Plow
[br]Nav- I enjoy pudding as much as the next person, but I'm not sure how to try it "on low power." I usually try pudding with a spoon, which does not have power settings. Perhaps you could lend me an adjustable electro-pneumatic spoon, so I can try pudding on low power?

If you're going to critique someone's spelling, well... ;)
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

<img src="http://www.petitewines.co.uk/jump_images/535_IMAGE2.jpg">
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Postby fullmetaljacket » Sun Jan 15, 2006 4:11 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by SMOMW</i>
fullmetaljacket, go and try to jump as high as you can, did you land in the same place or did you move opposite the earth's movement and land a few feet away?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Can you jump as high as your launchers shoot? Once it leaves contact with the Earth's surface (ie leaves the muzzle), the rotating force is no longer imparted on the projectile so the rotational component of its motion will slow down in relation to the Earth's rotation due to friction with the atmosphere.
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Postby fullmetaljacket » Sun Jan 15, 2006 4:13 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by orangekid13</i>not true... objects in motion tend to stay in motion<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
...unless slowed down by factors such as air resistance ;)
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Postby clide » Sun Jan 15, 2006 4:46 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fullmetaljacket
Can you jump as high as your launchers shoot? Once it leaves contact with the Earth's surface (ie leaves the muzzle), the rotating force is no longer imparted on the projectile so the rotational component of its motion will slow down in relation to the Earth's rotation due to friction with the atmosphere.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

But the atmosphere is also rotating at the same speed as the earth (give or take some due to wind). So it can't slow it down.

And there is no "rotating force" a force causes acceleration, not velocity. The earth and every thing on it are already rotating with a certain velocity, so in order to change that you must apply a force, a lack of force will not change the velocity.
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Postby Lord of the Rings Junkie » Sun Jan 15, 2006 4:59 pm

Thank god for inertia, if it weren't for that if we jumped in the air for 1 second when we landed we would be .3 miles away from where we first jumped! (Assuming you jump on the equator, worst case scenario) And it's even worse if you include our speed around the sun! A one second jump would land you almost 20 miles away!
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Postby Mr.Plow » Sun Jan 15, 2006 6:15 pm

clide- If there is air resistance though, the projectile will slow down, regardless of how much the atmosphere rotates at the same speed of the earth. Its like WWII cruisers, but on a much smaller scale. When trying to shoot a target miles away with a 16" cannon, one had to take into account where the shell would land after the earth had rotated during flight. Even if the target was static and the firing ship's position did not move (assume that the ship's direction and speed was already accounted for), the earth's rotation must be included in the calculation. I don't remember much from high school physics, but I'll never forget my teacher's multiple lectures on navy cannonry (he was in the navy for years, and let everyone know that at every possible time:D).
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