Gravity is an attractive force. This doesn't mean it's pretty. What "attractive" means is that an object's gravity pulls other objects toward it. Look at the chart. The Earth's gravity naturally pulls us, and everything else, toward the center of the planet, which keeps us from drifting off into space.

The Earth isn't the only thing that has gravity. In fact, and I know this is hard to believe, but every single object in the universe has gravity. The computer monitor you're looking at right now has gravity. It is pulling you toward it. You have gravity, and you are pulling the monitor toward you. We can't see or feel these things happening because people and computer monitors have a such a small mass that the effects of gravity cannot be seen. Mass is the amount of stuff contained inside an object. It takes a lot of mass to make a lot of gravity. The Earth has a lot of mass, so it has a lot of gravity. The moon's gravity is about 1/6 the amount of the Earth's because the moon has less mass than the Earth.

So what does all this have to do with weight? Well, weight is the force on a object caused by gravity trying to pull the object down. A scale measures how much gravity your mass has. A person with more mass has more gravity, and therefore weighs more.

You've probably seen video footage of astronauts walking on the moon. They seem to float between each step. Remember when I said that the moon has about 1/6 the amount of gravity that the Earth has? Well, if you went to the moon, you'd weigh less than you do here on Earth. Does this mean you would suddenly be thinner on the moon? Absolutely not. Your mass would be the same -- there is no less of you on the moon. But your weight is different because the moon's gravity is different.

 

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