Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Gravity is a non-contact force that pulls objects toward each other. On Earth, gravity pulls everything toward the center of the planet, which we see as 'down'.
Mass is the amount of matter (or 'stuff') inside an object. It is measured in kilograms () or grams (). Mass stays the same no matter where you are in the universe.
Weight is a measure of the pull of gravity on an object. Because weight is a force, it is measured in Newtons ().
The strength of gravity on Earth is approximately . This means that for every of mass, Earth pulls with of force.
Air resistance is a force that acts in the opposite direction to gravity when an object falls through the air, slowing it down.
📐Formulae
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💡Examples
Problem 1:
An apple has a mass of . Calculate its weight on Earth where gravity is .
Solution:
Explanation:
To find the weight, we multiply the mass of the apple () by the Earth's gravitational pull (). The result is Newton.
Problem 2:
If a toy car has a mass of , what would its weight be on Earth?
Solution:
Explanation:
Using the formula , we take the mass of and multiply it by the gravity constant of to get .
Problem 3:
If you travel to the Moon, where gravity is much weaker than Earth, would your mass of change?
Solution:
No, the mass remains .
Explanation:
Mass is the amount of matter in your body and it does not change based on location. However, your weight would decrease because the Moon's gravitational pull is weaker than Earth's.