Density
A substance's mass per unit volume.
Unit Density
Formula
Mass
Measure of the amount of matter a substance contains.
Unit Mass
Formula
Volume
The amount of space taken up by a substance.
Unit Volume
Formula
Weights on a Balance
Two weights balanced on a beam on a pivot at its center, positioned at equal distances from the pivot, have equal mass.
0 = W1
If they differ in weight, the heaver weight has to be closer to the pivot. Also the weights multiplied by their distances from the fulcrum are equal.
1 \times d1 = W0 \times d0