Density notes

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1.4: Density

To calculate density, you use the equation:

density (ρ) = mass (m) / volume (V)

Density of a regularly shaped solid

Measure the mass of the object using a balance. Make sure the balance reads zero before placing the object on it.

Then, measure its dimensions using a millimeter ruler/micrometer. Use the correct formula to find out its volume.

Density of an irregularly shaped solid

Use a balance to determine the mass of the object.

Determine the volume of the object using a beaker and a displacement can. The beaker is placed under a spout and the displacement can is filled with water until it overflows. The overflow beaker is emptied and replaced. The object is lowered on a thread into the water. The volume of the overflow collected is measured in a measuring cylinder to give the volume of the object.

Density of a liquid

Use a measuring cylinder to measure the volume of a certain amount of the liquid.

Then, measure the mass of an empty beaker using a balance. Remove the beaker from the balance and pour the liquid from the measuring cylinder into the beaker. Use the balance again to measure the total mass of the beaker and the liquid. The mass of the liquid is the mass of the beaker and liquid - mass of the empty beaker.

Can it float?

We can predict whether an object will float based on density data from the object. If its density is less than that of water, the object will float, however if it is more dense it will sink.