# buoyancy and water displacement

#### MrNeuro

##### Full Member
7+ Year Member
if you were to submerge two objects w/ different densities

density of obj 1 > density of obj 2

and you immersed both under water which would increase the level of water the most?

im pretty sure its the less dense object because density = mass/vol and greater volume = more displaced liquid (=greater buoyant force) = smaller density

BUT what if the question said that again density of obj 1 > density of obj 2 but this time vol obj 1 = vol obj 2 which one displaces more water assuming you submitted them to a force that kept them both under water????

##### Full Member
if you were to submerge two objects w/ different densities

density of obj 1 > density of obj 2

and you immersed both under water which would increase the level of water the most?

im pretty sure its the less dense object because density = mass/vol and greater volume = more displaced liquid (=greater buoyant force) = smaller density

BUT what if the question said that again density of obj 1 > density of obj 2 but this time vol obj 1 = vol obj 2 which one displaces more water assuming you submitted them to a force that kept them both under water????

it doesnt say anything about size so i think they would displace the same amount of water.

#### MrNeuro

##### Full Member
7+ Year Member
it doesnt say anything about size so i think they would displace the same amount of water.
hmmm what if they were both floating? i think the less dense ice cube w/ displace more if they're the same volume

#### pfaction

##### Full Member
10+ Year Member
It would have to depend on volume wouldn't it?

#### chiddler

##### Full Member
10+ Year Member
not enough info. need mass or volume.

#### MrNeuro

##### Full Member
7+ Year Member
i just finished an exam. could you tl;dr it for me please >.>
yeah sure

Vfreshwater = (pseawater/pfreshwater) Vdisplacedseawater

guy got that from archimedes

##### Full Member
if its floating then ... %V submerged = density object/density fluid and since density fluid is the same, whichever has the highest density has the highest % submerged

but again if both are completely submerged we dont know b/c density doesnt tell us anything about size

#### chiddler

##### Full Member
10+ Year Member
yeah sure

Vfreshwater = (pseawater/pfreshwater) Vdisplacedseawater

guy got that from archimedes

i don't understand the relevance of this to your question. can you please explain more?

to give an example of what i mean when i say you need more info, all you have said is that there is rho1 and rho2. nothing else. which increases volume of water when immersed?

my question to you is what if the very dense one has a LOT of mass such that a lot of water is displaced and the light one has very little mas such that little water is displaced?

#### MrNeuro

##### Full Member
7+ Year Member
i don't understand the relevance of this to your question. can you please explain more?

to give an example of what i mean when i say you need more info, all you have said is that there is rho1 and rho2. nothing else. which increases volume of water when immersed?

my question to you is what if the very dense one has a LOT of mass such that a lot of water is displaced and the light one has very little mas such that little water is displaced?
my question is does volume only affect displacement of water or does mass also affect the amount of displaced water. my guess is the former

#### chiddler

##### Full Member
10+ Year Member
if we're talking floating, then consider this:

if you have a very sparse solid (opposite of dense) that has 10g of material and 10 L volume, then it'll displace enough volume of water to equal 10g.

if you have a more dense solid with 10g of material and 1L volume, then it will displace the exact same amount of water.

no matter what you do, the weight of water displaced will equal the weight of the solid.

so now to answer your specific question, if we hold mass to be constant, then volume will not matter. as long as it floats, the amount of water displaced will be the same.

#### MrNeuro

##### Full Member
7+ Year Member
if we're talking floating, then consider this:

if you have a very sparse solid (opposite of dense) that has 10g of material and 10 L volume, then it'll displace enough volume of water to equal 10g.

if you have a more dense solid with 10g of material and 1L volume, then it will displace the exact same amount of water.

no matter what you do, the weight of water displaced will equal the weight of the solid.

so now to answer your specific question, if we hold mass to be constant, then volume will not matter. as long as it floats, the amount of water displaced will be the same.
yeah i know that im talking about a fully immersed object though

im pretty sure its just dependent upon the volume of the immersed object

#### chiddler

##### Full Member
10+ Year Member
=/

then it depends on density and mass.

unless we hold volume constant.

#### MrNeuro

##### Full Member
7+ Year Member
=/

then it depends on density and mass.

unless we hold volume constant.
LOL so then back to my original question

if you have two ice cubes w/ different densities lets say rho 1 > rho medium (hence it sinks) and rho 2 < rho medium hence it floats and lets say that V1 = V2 obviously rho 1 will displace more fluid than rho 2

rho 2 < rho 1 equivalent volumes but all of rho 1's mass is immeresed

but now lets say we've immersed object 1 (rho 1) does it displace the same volume as rho 2 even though it weights less?

#### milski

##### 1K member
5+ Year Member
LOL so then back to my original question

if you have two ice cubes w/ different densities lets say rho 1 > rho medium (hence it sinks) and rho 2 < rho medium hence it floats and lets say that V1 = V2 obviously rho 1 will displace more fluid than rho 2

rho 2 < rho 1 equivalent volumes but all of rho 1's mass is immeresed

but now lets say we've immersed object 1 (rho 1) does it displace the same volume as rho 2 even though it weights less?

If V1=V2 and they're both fully immersed, they both displace the same volume of liquid. The buoyant force does. Of really matter at that point - only the volume of the object that you submerge. It's just two things not being at same place at the same time.

#### pfaction

##### Full Member
10+ Year Member
So lemme make it clear Milski.

You have a 1 cubic meter ice ball, and a 1 cubic meter bowling ball. You immerse one in separate forty liters of water. The tanks will increase by 1 cubic meter, is that right?

#### milski

##### 1K member
5+ Year Member
So lemme make it clear Milski.

You have a 1 cubic meter ice ball, and a 1 cubic meter bowling ball. You immerse one in separate forty liters of water. The tanks will increase by 1 cubic meter, is that right?
Yes, as long as they are both fully submerged in the water and there is enough water for that to happen. In the case of ice ball, you'll need to push it for that to happen, so better example would be a cheese ball and a lead ball.

#### pfaction

##### Full Member
10+ Year Member
Ah yeah, that makes more sense--I wanted to choose ice because it's clearly less dense than water, but yeah. Sweet!

#### MrNeuro

##### Full Member
7+ Year Member
Thanks Milski. Lol. You're going to destroy your mcat.

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