Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Mass is the amount of matter (or 'stuff') in an object. It is measured in kilograms () or grams ().
Mass stays the same no matter where the object is in the universe.
Weight is a force caused by gravity pulling on an object's mass. Because it is a force, it is measured in Newtons ().
Weight changes depending on the strength of gravity. For example, you would weigh less on the Moon than on Earth because the Moon has weaker gravity.
Gravity () on Earth is a constant pull of approximately (often rounded from for Grade 5 level).
Mass is measured using a balance scale, while Weight is measured using a spring scale or Newton meter.
📐Formulae
💡Examples
Problem 1:
A school bag has a mass of . What is its weight on Earth?
Solution:
Explanation:
To calculate the weight, we multiply the mass () by the Earth's gravitational field strength ().
Problem 2:
An astronaut weighs on Earth. If they travel to the Moon, where gravity is only , what happens to their mass?
Solution:
The mass remains exactly the same as it was on Earth.
Explanation:
Mass is the amount of matter in the body. While the astronaut's weight will decrease on the Moon because gravity is weaker, their mass does not change.
Problem 3:
If a rock weighs on Earth, what is its mass?
Solution:
Explanation:
By rearranging the formula, we divide the weight () by the gravity () to find the mass in kilograms.