1. What is Mass?

2. Mass
We use the word mass to talk about how much matter there is in something. (Matter is anything you can touch physically.)

3. Weight
The difference between mass and weight is that weight is determined by how much something is pulled by gravity.
If we are comparing two different things to each other on Earth, they are pulled the same by gravity and so the one with more mass weighs more.
. But in space, where the pull of gravity is very small, something can have almost no weight. It still has matter in it, though, so it still has mass

4. Mass is how heavy something is without gravity
Another way of describing mass is: Mass is how much matter an object has
Mass is measured in grams (g) or kilograms (kg)

5. More about Mass
A common mistake is to think of Mass and Weight as the same thing because the word weight is often used when mass was really meant
When we talk of our weight we think about how heavy we are!
What we don't always take into consideration is gravity and how this effects how heavy we are!
Our mass is how heavy we are!
Our weight is how heavy we are on this planet! (with it's gravitational pull down!)

6. Density
Since the weight is a force, its SI unit is the newton. Density is mass/volume.
one gram is defined as the mass of 1 cm3 of water.

7. The Density of water is 1g/cm3
The Density of water is 1g/cm3. An object will float if the density is less than 1. An object will sink if its density is greater than 1.
mass times the acceleration of gravity, w = mg