Density calculation for a cork (less dense than water)

In summary, the conversation discusses the process of calculating the density of a cork, using a sinker and measuring the mass in air and water. The formula for specific gravity and density is also mentioned. The question arises regarding the correct notation for the mass difference, but it is concluded that the positive value obtained for density is correct.
  • #1
~christina~
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[SOLVED] density calculation for a cork (less dense than water)

Homework Statement



I was in lab and I had to calculate the density of a cork.
I used a sinker and measured how much the sinker weighed in water.
I measured how much the cork weighed in air. Then I tied the cork to the sinker and measured how much both weighed in water.

Not sure how to calulate the specific gravity and density however.

m1-m1= mo - mo'

sp. gravity= mo/ (m1-m2) = density

data:

mass cork in air : 8e-4kg

mass of cork and sinker with only sinker submerged: .11119kg

mass of cork and sinker with both submerged : .108kg


I was thinking that I'm not quite sure what the book means (notation wise)

but

sp gravity= 8e-4kg/ (.11119kg - .108kg) = density

sp gravity= .2507

density = .2507 g/cm^3

the thing was that I'm not sure whether the m1-m2 is the
m (sinker submerged)- m(sinker and cork submerged) because then it would be a positive value for density and that would technically be correct.

The book seems to explain it's the other way around with the m (sinker and cork submerged)- m(sinker submerged) but then it would be negative so I'm confused on that.

which way is correct?

Thank You
 
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  • #2
Densities are positive--you did it correctly. I'm pretty sure it's that way because the cork is relatively heavier in air than in water (it floats in water and not air) so subtracting the mass of the cork/sinker combination with the cork still in air minus the mass of the cork/sinker combination in water should be positive.
 
  • #3
Thank you, that's what I thought.
 

FAQ: Density calculation for a cork (less dense than water)

What is density and how is it calculated?

Density is a measure of how much mass is contained in a given volume of a substance. It is calculated by dividing the mass of the substance by its volume.

How do you determine the density of a cork?

To determine the density of a cork, you will need to measure its mass and volume. The mass can be measured using a scale, and the volume can be calculated by measuring the dimensions of the cork and using the formula for the volume of a cylinder (V = πr^2h). Once you have the mass and volume, simply divide the mass by the volume to get the density.

Why is a cork less dense than water?

A cork is less dense than water because of its composition. Cork is made up of a lot of air pockets, which makes it less dense than the solid water molecules. This means that a cork will float on top of water.

What are some common units used for density?

The most commonly used units for density are grams per cubic centimeter (g/cm^3) and kilograms per cubic meter (kg/m^3).

How does the density of a cork affect its ability to float?

The density of a cork affects its ability to float because objects with lower density than a liquid will float on top of that liquid. Since a cork has a lower density than water, it is able to float on top of the water's surface.

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