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5:47 pm, Dec 15 2009
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Ah, see, I know that equation and how to find the density. What confuses me is that the given volume V is not the same volume it's asking (above the water). I guess I'll call it Vo.

M V and X are given. I need to find Vo and F.

I really appreciate your effort though c:

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5:59 pm, Dec 15 2009
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Well you made it seemed like you knew nothing, but apparently you don't lol

That just makes the equation become

F = pgVo - mg, maybe its working on the principle that if he/she floats resultant force = 0? F = 0 ?

then pgVo = mg

Then when a force F is applied you can,

F = pgVf - mg

where Vf is the new volume (Vo-X)

If sign conventions confuse you (you get a negative answer)
use

(delta)F = pg(delta)V - (delta)mg (taken from derivation)

there (delta)m is 0 and (delta)V is X

you get the equation (delta)F = pgX which removes the negative from the answer.

Edit: Helps to read the question lol, thought X was distance in meters not a volume >.<, and I didn't notice the changing of volume above water into volume submerged in water.

Last edited by Noobsrus at 6:58 pm, Dec 15 2009

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Post #342276 - Reply to (#342274) by Noobsrus
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6:16 pm, Dec 15 2009
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Quote from Noobsrus
Well you made it seemed like you knew nothing, but apparently you don't lol

Wah! so mean! I'm just not great with Physics and anything math related. I'm an arts and literature kind of person. I'm really not stupid >_<


Let me work with that and see.





Post #342278 - Reply to (#342276) by MasamiAkane
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6:19 pm, Dec 15 2009
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Quote from MasamiAkane
Quote from Noobsrus
Well you made it seemed like you knew nothing, but apparently you don't lol

Wah! so mean! I'm just not great with Physics and anything math related. I'm an arts and literature kind of person. I'm really not stupid >_<


Let me work with that and see.





I didn't say you were, I was just saying that you underestimated yourself alot before actually posting the question, so I thought I'd have a run down at the basics, but you don't give yourself enough credit ^^.

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Post #342281 - Reply to (#342274) by Noobsrus
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6:22 pm, Dec 15 2009
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Quote from Noobsrus
where Vf is the new volume (Vo-X)

wiki to the rescue

It seriously solves this problem and explains it brilliantly.


Last edited by story645 at 6:33 pm, Dec 15 2009

Post #342282 - Reply to (#342281) by story645
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6:24 pm, Dec 15 2009
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Quote from story645
Quote from Noobsrus
where Vf is the new volume (Vo-X)

wiki to the rescue
It seriously solves this problem and explains it brilliantly.


You talking about the equation

(delta)F = pg(delta)V - (delta)mg?

Why did you quote that last bit, I'm a bit curious lol. Plus there really doesn't need any explaining the only major step was knowing that the net forces in a floating object = 0. He knew the rest (or was it a she I don't remember)

Last edited by Noobsrus at 6:31 pm, Dec 15 2009

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Post #342287 - Reply to (#342282) by Noobsrus
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6:34 pm, Dec 15 2009
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Quote from Noobsrus
You talking about the equation

No, the written explanation of Archimedes.

Quote
Why did you quote that last bit, I'm a bit curious lol.

Dunno honestly, I think I meant to quote something else or that's where it seemed like somebody got confused.


Post #342288 - Reply to (#342287) by story645
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6:37 pm, Dec 15 2009
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Quote from story645
Quote from Noobsrus
You talking about the equation

No, the written explanation of Archimedes.

Quote
Why did you quote that last bit, I'm a bit curious lol.

Dunno honestly, I think I meant to quote something else or that's where it seemed like somebody got confused.


Fine with me I thought I did something horribly wrong haha

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Post #342293 - Reply to (#342266) by MasamiAkane
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6:47 pm, Dec 15 2009
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Quote from MasamiAkane
A person with a mass of M and a volume of V floats on the water. What is the volume of the person above the water?

When an upward force is applied, the volume of the person above the water is increased by X. What is F?


bouyance force: F=mg=pVg

m is mass of water
p is density of water
V is volume of water displaced, which also equals the volume of the mass that is submerged.

weight of person w=Mg

M is mass of person, which you said was given so you can solve for w.

If the object is floating then weight of object is equal to bouyancy force.

w=F=pVg

therefore w=pVg and you can solve for V (the volume of the mass submerged).

To solve for volume of person above water just subtract the volume submerged from volume of the person.

That's what I got for your first question. Sorry if I repeated what anyone else said (I just skimmed over it).


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7:27 pm, Dec 15 2009
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Thank you everyone! I've got it. One thing I was doing wrong was using the density of the person instead of the water, so my numbers were not agreeing.

I might post a couple more later.

Post #342311 - Reply to (#342309) by MasamiAkane
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7:34 pm, Dec 15 2009
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Quote from MasamiAkane
Thank you everyone! I've got it. One thing I was doing wrong was using the density of the person instead of the water, so my numbers were not agreeing.

I might post a couple more later.


That is one issue with just putting up an equation, you may end up having some trouble defining your variables. I suppose I could have specified more lol.

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Everyone sounds so smart. D:



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Post #342319 - Reply to (#342317) by StarlightDreams
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7:48 pm, Dec 15 2009
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Quote from StarlightDreams
Everyone sounds so smart. D:


Thats cause we are!
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Post #342334 - Reply to (#342319) by Calíbre
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8:52 pm, Dec 15 2009
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Quote from Calíbre
Quote from StarlightDreams
Everyone sounds so smart. D:


Thats cause we are!
rawr



awww....we all like to show off our awesome math skills. laugh

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Post #342340 - Reply to (#342334) by BoxBox
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9:30 pm, Dec 15 2009
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Quote from BoxBox
Quote from Calíbre
Quote from StarlightDreams
Everyone sounds so smart. D:


Thats cause we are!
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awww....we all like to show off our awesome math skills... laugh

...to help others cool ( and perhaps help ourselves )

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