LESSON 17: MASS

Do you still remember what mass is, from Grade 5?

Mass measures the quantity of matter (particles) in an object. Mass is measured in gram (g), kilogram (kg) and ton (t). In Grade 6, we only work with gram and kilogram.

We sometimes refer to weight when talking about mass, but they are not the same thing.

What is the difference between mass and weight?

Mass

• Mass measures the quantity of matter (particles) in an object. • Mass always stays the same, regardless of where it is measured. • The standard unit is kilogram (kg).

Weight

• The weight of an object is determined by gravity. • Weight can change, depending on where it is measured. • The standard unit is Newton (N).

This picture will help you understand the difference. An astronaut’s mass is 90 kg, but his weight here on earth and on the moon, is different. On earth, the astronaut’s mass is 900 N, while on the moon it is merely 15,24 N!

Calculating weight is complicated, but you do not have to do that yet. You will learn more about mass and weight in Natural Sciences, later on.