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Physics Problem: what % barrel floating above water
November 20, 2011 at 8:24 pm
A solid cylinder (radius 0.150m height 0.120m) has a mass of 7 kg. The cylinder is floating on water, but oil (r=875kg/m^3) is added to the container, the cylinder gets covered by the oil. What % of the cylinder is above water?
I think that that 100% of the solid cylinder is floating above water because the cylinder is less dense than the water and the oil. density_cylinder = (mass_cylinder) / (pi*(radius^2)*h) = (7) / (pi*(0.15^2)(0.120) = 825.248kg/m^3
However, I can't believe the problem is that easy. I must be doing something wrong.
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 8:43 pm
So it didn't sink huh?
You are currently experiencing a lucky and very brief window of awareness, sandwiched in between two periods of timeless and utter nothingness. So why not make the most of it, and stop wasting your life away trying to convince other people that there is something else? The reality is obvious.
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 9:09 pm
(November 20, 2011 at 8:43 pm)Norfolk And Chance Wrote: So it didn't sink huh?
I don't think so, but if you can show me otherwise, that would be nice.
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 9:16 pm
(November 20, 2011 at 8:24 pm)The_Flying_Skeptic Wrote: A solid cylinder (radius 0.150m height 0.120m) has a mass of 7 kg. The cylinder is floating on water, but oil (r=875kg/m^3) is added to the container, the cylinder gets covered by the oil. What % of the cylinder is above water?
I think that that 100% of the solid cylinder is floating above water because the cylinder is less dense than the water and the oil. density_cylinder = (mass_cylinder) / (pi*(radius^2)*h) = (7) / (pi*(0.15^2)(0.120) = 825.248kg/m^3
However, I can't believe the problem is that easy. I must be doing something wrong.
The floating cylinder would displace 7kg (plus whatever is added to it) of water.
You make people miserable and there's nothing they can do about it, just like god.
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 9:30 pm
(November 20, 2011 at 9:16 pm)IATIA Wrote: (November 20, 2011 at 8:24 pm)The_Flying_Skeptic Wrote: A solid cylinder (radius 0.150m height 0.120m) has a mass of 7 kg. The cylinder is floating on water, but oil (r=875kg/m^3) is added to the container, the cylinder gets covered by the oil. What % of the cylinder is above water?
I think that that 100% of the solid cylinder is floating above water because the cylinder is less dense than the water and the oil. density_cylinder = (mass_cylinder) / (pi*(radius^2)*h) = (7) / (pi*(0.15^2)(0.120) = 825.248kg/m^3
However, I can't believe the problem is that easy. I must be doing something wrong.
The floating cylinder would displace 7kg (plus whatever is added to it) of water.
Nothing is added to the cylinder. The cylinder is solid. I made the mistake of saying the cylinder was a barrel in the title but it's just a solid cylinder. The cylinder is in a container full of water, and oil is added to the container. If enough oil was added to the container that cylinder gets covered by the oil...
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 9:49 pm
So, oil is poured "over" this cylinder, but not into it, and it is not a porous object?
Trying to update my sig ...
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 11:39 pm
(November 20, 2011 at 9:49 pm)Epimethean Wrote: So, oil is poured "over" this cylinder, but not into it, and it is not a porous object?
yes. This is what I understand from the problem. It's a solid cylinder and no oil or water is getting into it.
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RE: Physics Problem: what % barrel floating above water
November 20, 2011 at 11:39 pm
(November 20, 2011 at 9:30 pm)The_Flying_Skeptic Wrote: (November 20, 2011 at 9:16 pm)IATIA Wrote: (November 20, 2011 at 8:24 pm)The_Flying_Skeptic Wrote: A solid cylinder (radius 0.150m height 0.120m) has a mass of 7 kg. The cylinder is floating on water, but oil (r=875kg/m^3) is added to the container, the cylinder gets covered by the oil. What % of the cylinder is above water?
I think that that 100% of the solid cylinder is floating above water because the cylinder is less dense than the water and the oil. density_cylinder = (mass_cylinder) / (pi*(radius^2)*h) = (7) / (pi*(0.15^2)(0.120) = 825.248kg/m^3
However, I can't believe the problem is that easy. I must be doing something wrong.
The floating cylinder would displace 7kg (plus whatever is added to it) of water.
Nothing is added to the cylinder. The cylinder is solid. I made the mistake of saying the cylinder was a barrel in the title but it's just a solid cylinder. The cylinder is in a container full of water, and oil is added to the container. If enough oil was added to the container that cylinder gets covered by the oil...
Unless it is floating in the oil, it will still displace some water. It will be somewhere around 7kg - the weight of the displaced oil. A little more math than that, but right now I am not in math 'mode'.
You make people miserable and there's nothing they can do about it, just like god.
-- Homer Simpson
God has no place within these walls, just as facts have no place within organized religion.
-- Superintendent Chalmers
Science is like a blabbermouth who ruins a movie by telling you how it ends. There are some things we don't want to know. Important things.
-- Ned Flanders
Once something's been approved by the government, it's no longer immoral.
-- The Rev Lovejoy
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RE: Physics Problem: what % barrel floating above water
November 21, 2011 at 1:22 am
(November 20, 2011 at 11:39 pm)IATIA Wrote: Unless it is floating in the oil, it will still displace some water. It will be somewhere around 7kg - the weight of the displaced oil. A little more math than that, but right now I am not in math 'mode'.
It really comes down to how much oil is added to the water. If there is only a small amount at the surface, it isn't going to significantly affect the calculations.
If, on the other hand, if there is a substantial amount, you have to factor in how much oil is displaced along with the water.
If it's floating entirely in oil, the calculations become simple again, you'll just be displacing 7kg of oil instead of water.
You really do need to know how much oil there is to do this problem.
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RE: Physics Problem: what % barrel floating above water
November 21, 2011 at 2:10 am
(November 21, 2011 at 1:22 am)I_Blaspheme Wrote: (November 20, 2011 at 11:39 pm)IATIA Wrote: Unless it is floating in the oil, it will still displace some water. It will be somewhere around 7kg - the weight of the displaced oil. A little more math than that, but right now I am not in math 'mode'.
It really comes down to how much oil is added to the water. If there is only a small amount at the surface, it isn't going to significantly affect the calculations.
If, on the other hand, if there is a substantial amount, you have to factor in how much oil is displaced along with the water.
If it's floating entirely in oil, the calculations become simple again, you'll just be displacing 7kg of oil instead of water.
You really do need to know how much oil there is to do this problem.
I believe this is the standard buoyancy problem and there is enough oil to completely encompass the cylinder. In high school, mine was a block of wood.
You make people miserable and there's nothing they can do about it, just like god.
-- Homer Simpson
God has no place within these walls, just as facts have no place within organized religion.
-- Superintendent Chalmers
Science is like a blabbermouth who ruins a movie by telling you how it ends. There are some things we don't want to know. Important things.
-- Ned Flanders
Once something's been approved by the government, it's no longer immoral.
-- The Rev Lovejoy
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