Density is a physical property of materials. Knowing the density of a material is important for determining whether something will float or sink. This is an important consideration in areas like construction and engineering. It is also a measurement used to identify different materials. Calculating speed and acceleration is important for studying objects in motion.
28.1 Density
The density of a substance is the relationship between its mass and the amount of space it takes up. In other words, density refers to how much matter is packed into a given volume. Some substances are more dense than others. This means that the matter in them is packed more tightly.
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and Acceleration
Density The density of a substance is its mass per unit volume.
Fig. 1 These objects have the same volume but object A is more dense than object B.
The size, mass and arrangement of atoms in a substance all influence its density. Imagine you are holding two blocks. They are exactly the same size and shape, but one is made of concrete and one is made of polystyrene. Which is more dense? Hint: If you have two objects of the same volume, the object that is more dense will be heavier than the less dense object. The concrete block has a higher density. Although it takes up the same amount of space as the polystyrene block, the concrete block has more matter packed into it. The molecules in concrete have a higher mass and they are packed more tightly together than the molecules in polystyrene. In addition, polystyrene has pockets of air.
