Density:

Density = measure of the compactness of a substance.

Density = mass/volume

The density of an object depends on what it's made of and doesn't vary with size or shape. The average density of an object determines whether it sinks or floats - a solid object will float on a fluid if it has a lower average density than the fluid.

How do you measure the density of solids and liquids?

To measure the density of a substance, measure the mass and volume of a sample of the substance and use the equation above. You can measure the mass of an object using a mass balance. To measure the volume of a liquid, you can just pour it into a measuring cylinder.

If you want to measure the volume of a solid cuboid, measure its length, width and height then multiply them together. To find the volume of a solid cylinder, measure the diameter of one of the bases, then halve this to find the radius. Measure the height and then use volume = pi x radius^2 x height.

An object that is submerged in water will displace a volume of water equal to its own volume. Use the Eureka can to do this.

Eureka Can Experiment:

You need the eureka can to be filled so that the water level is just under the spout.
Place a measuring cylinder under the spout, then gently lower your object into the can.
Wait for the spout to stop dripping, then measure the volume of the water collected. This is the volume of the water displaced by the object which is equal to the volume of the object.
Repeat this three times and calculate a mean to find the average volume of an irregular object.

	Created by Chloe Wood over 5 years ago

GCSE Physics Note on P1 Revision , created by Chloe Wood on 17/03/2021.