Density

Today in Science we talked about what density is and how we calculate the density of a specific object.

Density is a measurement of how solid something is. Specifically it is the mass per unit volume of a substance. If you have two objects of the exact same size (volume), the more dense object will weigh more than the less dense object.

So there are two things contributing to density:

1.      The mass of the atoms or molecules that makes up the material.

2.      The volume or amount of space the material takes up. If the molecules or atoms are “packed” in more closely, it will be more dense.

For example, styrofoam is a low density material. Even a large styrofoam container does not weigh much. The molecules in the styrofoam do not have much mass and there is a lot of space between them. A brick, on the other hand, is much more dense. Even a moderate sized brick can be pretty heavy. This is because the molecules which make up the rock have more mass and are packed more closely together.

Density and buoyancy are closely related. A less dense substance will float on a more dense substance.

 Words to Know:

Density – How closely packed together the molecules of a substance are.

Bouyancy – Ability to float or rise to the top of a liquid or gas.

Float – To sit near the surface of a liquid or gas, to not sink.
Mass - How much matter fits in a given space.
Matter - Stuff
Weight - A measure of the force of gravity on an object. Materials with more density weigh more.
Volume – How much space a substance takes up.

Formula for Density:

d= m/v

Remember: v= l x w x h

**Tomorrow we will be completing a number of labs to really understand density**

Math Homework
Page 219-221  #4,5,6,8,9 and #11,12,13,15,17