Gold Band 9
WHAT IS GRAVITY?
S I T A WH ITY? V A R G
Have you ever wondered why gravity doesn’t weigh us down, or why astronauts can float in space? Find out all of the answers to these questions, and more! Browse the complete Collins catalogue at
www.collins.co.uk
An information book
Isabel Thomas
www.collins.co.uk/collinsbigcat
54807_Cover.indd 1
23/03/2021 15:06
Is gravity the strongest force?
2
54807_P001_024.indd 2
23/03/2021 15:09
What is gravity? If you’ve ever fallen over or broken something by dropping it, you can blame gravity! This invisible force attracts objects towards each other. Every object has gravity, from planets to people.
3
54807_P001_024.indd 3
23/03/2021 15:09
Does that mean this book has gravity? That’s right – you’re being pulled towards this book right now! Your own gravitational force is also attracting the book towards you.
So why doesn’t the book move towards me? Gravity comes from the mass of an object – the amount of stuff it’s made from. The greater the mass, the greater that object’s gravitational pull. Earth has enormous mass, so the pull between you and Earth is strong. It keeps you on the ground. The book’s mass is far smaller, so the pull between you and the book is far smaller too.
4
54807_P001_024.indd 4
23/03/2021 15:09
5
54807_P001_024.indd 5
23/03/2021 15:09
Is gravity the strongest force? It may not seem like it but gravity is a very weak force compared to other forces we come across every day. Each time you throw a ball, your muscles are overcoming gravity.
6
54807_P001_024.indd 6
23/03/2021 15:09
The stalk holding an apple on a tree is overcoming gravity.
Even a tiny insect crawling up a wall easily overcomes the gravitational force of the entire planet!
When you pick up paperclips with a magnet, the magnetic force is beating gravity.
7
54807_P001_024.indd 7
23/03/2021 15:09
Gold Band 9
WHAT IS GRAVITY?
S I T A WH ITY? V A R G
Have you ever wondered why gravity doesn’t weigh us down, or why astronauts can float in space? Find out all of the answers to these questions, and more! Browse the complete Collins catalogue at
www.collins.co.uk
An information book
Isabel Thomas
www.collins.co.uk/collinsbigcat
54807_Cover.indd 1
23/03/2021 15:06