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Q & A: Sinking Slowly

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Most recent answer: 10/22/2007
How do you get something to sink slowly?
- Andry H. (age 14)
Poulsbo Jr. High, Poulsbo, WA
Andry -

An object will sink in water if it is denser than water is - that is, if a certain volume of it weighs more than the same volume of water does. As for how quickly it will sink, there are several important factors. Density is one of them. The denser an object is, the heavier it will be. This will let it push through the water better as it falls - it will fall more quickly.

Shape is also important. A compact shape (like a sphere) doesn't have nearly as much friction with the water as a more spread-out shape- say like a screen. If you drop something compact (maybe a spoon) into water, it will sink more quickly than a strainer, even if the strainer has the same density and the same weight.

So if you wanted to make something sink slowly, you'd want it to be just dense enough to sink, and also to be spread out enough to have lots of friction with the water.


(published on 10/22/2007)

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