{"id":10366,"date":"2018-08-20T16:59:15","date_gmt":"2018-08-20T15:59:15","guid":{"rendered":"https:\/\/ounews.co\/?p=10366"},"modified":"2018-08-20T16:59:15","modified_gmt":"2018-08-20T15:59:15","slug":"curious-kids-how-does-gravity-pull-things-down-to-earth","status":"publish","type":"post","link":"https:\/\/www.open.ac.uk\/blogs\/news\/science-mct\/science-environment\/curious-kids-how-does-gravity-pull-things-down-to-earth\/","title":{"rendered":"Curious Kids: how does gravity pull things down to Earth?"},"content":{"rendered":"

This is an article from Curious Kids<\/a>, a series for children of all ages. The Conversation is asking young people to send in questions they\u2019d like an expert to answer. All questions are welcome: find details on how to enter at the bottom.<\/em><\/p>\n

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How does gravity pull things down to Earth? \u2013 Gabriel, age four, Stewartby, UK<\/strong><\/p><\/blockquote>\n

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Gravity is a force, which means that it pulls on things. But the Earth isn\u2019t the only thing which has gravity. In fact, everything in the universe, big or little, has its own pull because of gravity \u2013 even you.<\/p>\n

Isaac Newton was one of the first scientists to figure out the rules of how gravity behaves. The story goes, he was sitting under an apple tree when one of the fruits fell off. As he saw the apple fall down to the ground, he started to wonder why it didn\u2019t go up to the sky instead.<\/p>\n

After lots of experiments, and some very clever thinking, he worked out that the force of gravity depends on how heavy objects are, and that the pull of gravity between objects gets smaller, the further apart they are. To see how gravity works in our universe, we\u2019re going to take a journey, with a few stops along the way.<\/p>\n

First off, we\u2019ll go to the park and play a game of football. When you kick the football into the air, the Earth\u2019s gravity pulls it back down. But that\u2019s not the only thing that\u2019s happening: the gravity of the football is also pulling on the Earth. The thing is, the Earth is very big \u2013 much bigger than the football \u2013 so its pull is stronger and the football falls back down.<\/p>\n

Our next stop is the moon, and as we journey up into space, there\u2019s a good chance you\u2019ll see the sun. Now, the sun is much, much bigger than the Earth, which means its pull is very powerful indeed.<\/p>\n

You might be wondering why the Earth (and all the other planets) don\u2019t just fall into the sun, the same way the football falls to Earth. The answer is that the planets are all moving, and the balance between the force of gravity and the force from their movement keeps them circling round the sun.<\/p>\n

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Fly me to the moon.<\/span>
\nNASA’s Marshall Space Flight Center\/Flickr.<\/a>, CC BY-NC<\/a><\/span><\/figcaption><\/figure>\n

When we arrive on the moon, you\u2019ll see that the pull of gravity is not the same everywhere. It is related to how heavy \u2013 or how massive \u2013 an object is. If you jump on the moon, you\u2019ll be able to go much higher than you can on Earth. This is because the Earth is bigger than the moon, so the force between you and the Earth \u2013 which is what we call weight \u2013 is bigger than the force between you and the moon. On the moon, you seem to weigh less than on Earth, so you can jump higher.<\/p>\n

Our final stop is the seaside. Sitting on the beach, you can see the sea gradually getting closer and closer to you \u2013 this is the tide coming in. After some time, the sea seems to get further away \u2013 now, the tide is going out. But the sea is not actually moving in and out \u2013 it is moving up and down. As the sea level rises, the water gets closer to you, because the beach you are sitting on slopes upwards away from the sea. And as as the sea level drops down, the water gets further away from you.<\/p>\n