# Homework Help: AP PHYSICS ~ FLUIDS ~ A cube of osmium with a volume of

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1. Dec 5, 2012

### Silverbolt

A cube of osmium with a volume of 166 cm³ is placed in fresh water. The cube's apparent weight is 35.0 N. What is the density of osmium?

This is what I did:

I converted force to mass by : 35 N / 9.8 = 3.57 kg

then changed the 166 cm³ to m³ which is : .000166 m³

After that i divided the mass and the volume: (3.57 kg)/(.000166 m³)

And so I got the density as 21506 kg/m³

2. Dec 5, 2012

### dextercioby

What did you do with the Archimedes principle/force ?

3. Dec 6, 2012

### iilego

Your conversion from cm^3 to m^3 was off, it's actually 1.66m^3, you move it two decimal places to the left.

4. Dec 6, 2012

### AlephZero

That is correct, and iilego's post #3 is wrong.

The question says "the cube was placed in fresh water". You haven't used that information anywhere. What difference does it make if the cube is in water or in air?

5. Dec 6, 2012

### iilego

cm equals .01 meters, which is two decimal places to the left, am I wrong? I never mentioned anything about the answer, just that his conversion was off on the volume.

6. Dec 7, 2012

### SteamKing

Staff Emeritus
If 1 cm = 0.01 m, then (1 cm)^3 = 1 cm^3 = (0.01 m)^3 = 10^(-6) m^3

1m^3 is rather a large volume

7. Dec 7, 2012

### iilego

never mind, I was wrong, the conversion was right, sorry :(