Physics

Let’s learn about gravity

Gravity keeps you grounded and our planet spinning around the sun

Skateboard tricks rely on gravity — the force that attracts the skateboarder back to Earth. People can jump and spin, but they’ll always come back down.

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By Bethany Brookshire

January 13, 2021 at 6:30 am

What goes up must come down. On Earth, anyway. Why? There’s a lot of gravity to that situation. Gravity is the attraction that objects with mass have to other objects with mass. The more massive something is, the more gravity it has. The gravity from the Earth’s mass pulls on your body’s mass, keeping you here on Earth. Your body also has gravity, but it’s so tiny compared to the Earth that the Earth will always win.

Gravity is what pulls huge clusters of atoms together into stars, and chunks of matter into planets. It keeps planets in orbit around their stars, and moons in orbit around their planets. When a really giant star collapses in on itself, it can end up with so much mass — and so much gravity — that not even light can escape. The result is a black hole.

People are used to living with gravity. In fact, our bodies are so used to the gravitational pull of the Earth that without it, our bones and muscles get weak.

Want to know more? We’ve got some stories to get you started:

Say hello to gravity waves: Albert Einstein predicted these waves more than 100 years ago. Then scientists finally proved him right. (2/12/2016) Readability: 7.2

En route to Mars, astronauts may face big health risks: Going into space brings the thrill of a new frontier — and risks that scientists are racing to understand, from radiation to isolation to living without Earth’s gravity. (3/8/2018) Readability: 7.1

Here’s the first picture of a black hole: The Event Horizon Telescope imaged the supermassive beast lying some 55 million light-years away in a galaxy called M87. (4/10/2019) Readability: 7.8

Mass is constant. But weight is not. Weight is a measure of the force exerted by gravity, and so depends on where you weigh something. And gravity can vary depending on where you are on Earth!

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Explainer: What are gravitational waves?

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Researchers reveal the secret to the perfect football throw

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Do you know where your center of gravity is? You can find it with an easy at home experiment. Add a balancing pole and see how changing your center of gravity improves your balancing talent.