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United States24813 Posts
On September 26 2008 19:48 -orb- wrote:Show nested quote +On September 26 2008 19:33 micronesia wrote:On September 26 2008 11:29 Hippopotamus wrote: O RLY? Remember this timeless truth: It's only physics if the deer are perfectly spherical and there is no air resistance! The perfectly spherical one I'll give you, but I've had to do too much air resistance for you to say that! haha, but back in grade school/etc, they always ignored air resistance and it made me so fucking mad. They'd be like "John is riding on the back of a pickup truck. He throws a ball straight up in teh air while moving forward at 40 mph. When the ball comes back down, where will it land?" And obviously the REAL answer is behind him because of air resistance, but those asshole teachers were always like "NO IT LANDS BACK IN HIS HANDS LOLOL U LOSE" so I'm like fuck how about we go try it out to prove it and they're like "YOU GET AN F"
Are you saying they didn't understand it, or that they weren't recognizing publicly that it works differently? It's not that hard to play the game as a student if you understand it at that level.
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On September 26 2008 19:48 -orb- wrote:Show nested quote +On September 26 2008 19:33 micronesia wrote:On September 26 2008 11:29 Hippopotamus wrote: O RLY? Remember this timeless truth: It's only physics if the deer are perfectly spherical and there is no air resistance! The perfectly spherical one I'll give you, but I've had to do too much air resistance for you to say that! haha, but back in grade school/etc, they always ignored air resistance and it made me so fucking mad. They'd be like "John is riding on the back of a pickup truck. He throws a ball straight up in teh air while moving forward at 40 mph. When the ball comes back down, where will it land?" And obviously the REAL answer is behind him because of air resistance, but those asshole teachers were always like "NO IT LANDS BACK IN HIS HANDS LOLOL U LOSE" so I'm like fuck how about we go try it out to prove it and they're like "YOU GET AN F"
Since you do not know in which way the wind blows (it could blow 40 mph at the same direction as the truck) then you have to assume that any form of air resistance is negligible or the question is impossible to answer.
By the way, this question:
You got a closed half sphere metal shell with a radius of 2A. (Thinks half a sphere were the opening is bridged)
You got a point charge q at a height A above the middle of the flat part.
In which direction do the charge move? (No gravity or anything like that, just electrostatics)
a: up
b: stands still
c: down
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+ Show Spoiler +
I would think that if the dog is walking with the owner, if you threw it backwards, it takes some time to turn around.
If the owner can throw it equally strong in every direction, the stick would go the furthest if he threw it forward, but the dog is already moving in that direction so s/he doesn't have to turn around and accelerate
I really have no clue so I'm gonna say forward, a)
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This blog rocks! Physics is the shit, I can't understand why basically no one thinks so. Will you include anything with theoretical physics?
+ Show Spoiler + If you take this question as it is given to you (without raising any questions of your own, I would say d. If micronesia throws the stick multiple times it really does'nt matter where as yubee(lol) will be running constantly. If anything else applies though, I would say b.
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+ Show Spoiler +
Just read all the others spoilers, and I find it strange that not more ppl came up with this solution...
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+ Show Spoiler +B. assuming that the throw in any direction is equally far. then, if you throw backwards, you will have walked an extra vel_walk * time_dog, where vel_walk is your velocity in the forward direction and time_dog is the time it takes for the dog to get back to you, and likewise the dog will have run that extra amount as well.
sweet, can't wait for the E&M / Quantum / Relativity sections
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United States24813 Posts
On September 27 2008 01:17 Makhno wrote:
This blog rocks! Physics is the shit, I can't understand why basically no one thinks so. Will you include anything with theoretical physics?
I'm starting with a set source of questions, which includes only the topics listed in the OP. This will last us for a while, and I'm open to suggestions for where to go from there, but I probably am not worrying about that for a few days.
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On September 27 2008 01:17 Makhno wrote:
This blog rocks! Physics is the shit, I can't understand why basically no one thinks so. Will you include anything with theoretical physics?
Geology rocks, physics is just plain awesome.
And the further you get from boring High School mechanics the more things you get to stop ignoring, which is when it gets fun. Especially when progress through E&M, you go from spheres to all kinds of weird charge and current configurations.
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Canada7170 Posts
+ Show Spoiler +b. And I bet that lots of others already mentioned why.
But I'd probably shoot the dog asap 
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To further clarify others' reasonings...
+ Show Spoiler +
If it takes a negligible amount of time to take the stick from the dog and throw it again, one can assume that the dog is running the whole time, so it doesn't matter which direction Micronesia throws it in.
However, if it does take a certain amount of time to do this, Micronesia would want to throw the stick in the opposite direction of his movement, assuming he always throws it some distance D, regardless of direction, as this would lengthen each iteration of throwing and retrieving, and thereby reduce the time that Yubee is waiting for Micronesia to throw.
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On September 27 2008 01:00 Purind wrote:+ Show Spoiler +
I would think that if the dog is walking with the owner, if you threw it backwards, it takes some time to turn around.
If the owner can throw it equally strong in every direction, the stick would go the furthest if he threw it forward, but the dog is already moving in that direction so s/he doesn't have to turn around and accelerate
I really have no clue so I'm gonna say forward, a)
+ Show Spoiler +
Oh wait, I think I understand now. My answer was assuming that micro was walking, threw the stick then stood still immediately after
If micro keeps walking, and assuming he can throw it with the same strength (I see this as initial speed with which the stick gets thrown) the stick will have a velocity (micro's walking speed + throwing velocity), so the stick moves with the same speed relative to micro regardless of direction
I'm not that good with imagining stuff, but now that I think about it, if you throw forward, the thing will move faster (thus farther) but micro walks toward the dog, but if you throw backwards, the thing will move slower so the dog doesn't take long to retrieve it, but takes longer for the dog to go back to micro. I'm having trouble working this out in my head, but it seems that the forward and backward times will be the same, so I'll go with doesn't matter
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+ Show Spoiler +well you have to make a few assumptions, such as the dog has constant velocity and that the owner throws the stick equally far in each direction, otherwise you'd be able to come up with countless scenarios and it would be impossible to answer the question, also the time it takes for micro to take the stick from the dog should be negligible. So, as someone mentioned, it will just be velocity*time = distance, and that's the only thing that counts. If you throw it backwards, the dog has to run more with each throw, but you will have to throw less times, they are just countering each other.
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Germany2896 Posts
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EPT
