# Fluids Question

Discussion in 'MCAT Study Question Q&A' started by the lost crow, Jun 19, 2008.

1. ### the lost crow

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When an object sinks, why does the level of the fluid drop?

3. ### 161927 Guest

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the water level increases by the amount of water displaced by the sunken object. why would the water level drop? are you thinking of a cube of ice melting? that would be an entirely different case, and the water level would be observed to remain constant

4. ### engineeredout

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Fluid level could never drop because the volume that the object is displacing would be made up for by rising water level. Could you be more specific about what you're asking?

5. ### the lost crow

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Sorry about that, I meant like a let's say a boat sunk in water. Why exactly does the level of water drop? My tutor told us that the Volume of the boat basically is a function of the density of the boat rather than being a function of the density of water. That's what's been throwing me off hmmm...

6. ### seraph524 M0

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The fluid will never, ever drop. The density of the boat is irrelevant in this case. If it sinks, it will displace more water volume, leading to the water level rising.

7. ### ThePandaFactor

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Oh I think this is what you mean. If you throw something really dense over the side of the boat (denser than water) the total water level will drop since it will displace just the volume of the object, instead of the volume of the water that weighs the same as the object.

8. ### seraph524 M0

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Wait, so you are saying, if you throw something thats denser than water into a cup of water, then the water level will drop? Huh...

Try this, fill a glass completely full with water, and start throwing pennies in. See if the water doesn't overflow.

9. ### ThePandaFactor

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It would if you were throwing them off the side of a boat that was floating in the cup.

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