Gravity Explained
A primary physics lesson on gravity: learn why things fall down, how gravity holds us on Earth, why the Moon orbits us, and what weight means, with an experiment and quiz.
Key takeaways
- Gravity is a force that pulls objects toward each other.
- Earth's gravity pulls everything down toward the ground.
- The bigger and closer an object, the stronger its gravity.
- Weight is how strongly gravity pulls on you, so you weigh less on the Moon.
What is gravity?
Gravity is an invisible force that pulls objects toward each other. Like other pushes and pulls, you cannot see it, but you can see what it does.
Earth has a lot of gravity. It pulls everything toward the ground. That is why a dropped apple falls down and never floats up.
Why things fall down
Throw a ball into the air. It slows down, stops, and then comes back to your hands. Why? Earth's gravity is always pulling it back toward the ground.
Jump as high as you can — gravity pulls you back to the floor. Pour water and it splashes downward. Gravity is working all the time, every second of the day.
Gravity holds us on Earth
Gravity is the reason we can walk on the ground instead of floating away. It keeps:
- Your feet on the floor
- The air wrapped around our planet
- The oceans in their place
- Buildings and trees standing firm
Gravity always pulls toward the center of the Earth. So wherever you stand on the planet, "down" points toward the middle. People on the other side of the world do not fall off!
Bigger and closer means stronger
Everything with mass (the amount of stuff in it) has gravity, even you. But you are small, so your pull is tiny.
Two things make gravity stronger:
- Bigger objects have more gravity. Earth is huge, so its pull is strong. The Sun is far bigger still.
- Closer objects pull harder. The closer you are, the stronger the pull.
Earth's gravity even reaches all the way to the Moon. It pulls on the Moon and keeps it circling around us, which we call an orbit. In the same way, the Sun's gravity keeps Earth orbiting the Sun.
Weight: how hard gravity pulls
Weight is a measure of how strongly gravity pulls on you. On the Moon, gravity is much weaker because the Moon is smaller than Earth. So you would weigh about six times less on the Moon — you could jump super high! Your mass (how much stuff you are made of) stays the same; only your weight changes.
Try it yourself! 🪙
Test how gravity pulls on different objects.
- Hold a heavy coin in one hand and a crumpled ball of paper in the other, at the same height.
- Drop them at exactly the same time. Watch closely. They land at almost the same moment!
- Now flatten the paper out and drop it next to the coin again. This time the flat paper floats down slowly.
Gravity pulls them equally, but the flat paper is slowed by the air pushing on it. Without air, like on the Moon, everything falls at the same speed.
Stay safe: Drop only soft, light objects, and never anything that could break or hurt someone below.
Quick quiz
Test yourself and earn XP
What does gravity do?
Gravity is a pulling force that pulls objects toward each other.
Why does a ball fall back down when you throw it up?
Earth's gravity pulls the ball back down to the ground.
Where would you weigh the least?
The Moon is smaller than Earth, so its gravity is weaker and you weigh less there.
What keeps the Moon circling around Earth?
Earth's gravity pulls on the Moon and keeps it orbiting around us.
FAQ
Gravity always pulls toward the center of the Earth, so 'down' is always toward the ground no matter where you stand on the planet.
Yes. Gravity is everywhere. Astronauts seem to float because they are falling around the Earth in their spacecraft, not because gravity is gone.
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