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This is a fun article that has more about gravity. Follow the hyperlinks in the article to find out more about different aspects of the subject.

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Do you know what gravity is? Firstly gravity is so very important to the universe and how the universe works. It's also very important to our planet, and how it works, and how humans function. Actually it's just really important period! And here's why.

Without gravity, our universe wouldn't function the way we know it to, and neither would Earth. If gravity didn't exist you would literally fall off the planet and float away into space, along with everything else. So gravity is a force of nature that is there, and is key to our planet and the universe.

Like Dark Matter, and Dark Energy, we cannot see gravity so how do we know that it's there? Well first of all, we can thank the well-known historical physicist Sir Isaac Newton for discovering gravity. It was this great mind who one day discovered that objects of Matter are not just on the Earth, that they are actually pulled down to the earth by a force discovered as gravity.

Gravity is a strong force of nature, but not so strong that it actually pulls absolutely everything down all of the time so strongly. That wouldn't work either. However it is a force that keeps everything in check and in balance, and keeps us grounded.

Like when Newton and that famous story as to how he discovered gravity - the Apple fell from the tree, however the Apple grew and was connected to the tree, and came off naturally, hitting the ground. So what that means is that objects of matter are pulled to the ground with mid force once they have become free.

So you can climb the tree and gravity will not pull you and the tree down to Earth, but if you come away from the tree and fall, you are gown down!!

So while gravity keeps us grounded on earth, it does something different with the planets, stars, galaxies and the whole universe. Gravity brings and binds everything together, all the way through the cosmos.

Think of gravity as like the glue that sticks to the Earth and the universe, and helps everything work. Gravity is so special, we cannot do without it. If gravity didn't exist it would be a very strange universe!
Kids Fun Facts Corner
# 1. Gravity as a force compared to other forces in the universe is quite weak.

# 2. The tides in the oceans are governed by the gravitational forces of the Earth and its moon.

# 3. You would weigh differently on each planet than you would on Earth due to the different gravitational pull of each planet.
Q&A Corner
Q. What does gravity do in the universe?

Q. What would happen on Earth to humans if gravity didn't exist?

Q. Who is credited with discovering gravity?

Q. What was the food that fell to the ground discovering gravity?

Download questions about gravity here: gravity (answers on this page)

For further reading and more info on gravity visit www.easyscienceforkids.com/gravity

Key Vocabulary Universe. Planet. Earth. Matter.

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Do you know what gravity is? Firstly gravity is so very important to the universe and how the universe works. It's also very important to our planet, and how it works, and how humans function. Actually it's just really important period! And here's why.

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Video showing Galileo’s Gravity Experiment 

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Video showing Galileo’s Gravity Experiment 

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Watch this cool YouTube video about objects falling in a vacuum.

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Galileo's Famous Gravity Experiment | Brian Cox | BBC Two

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Download this handout and use Evernote to write an explaination about why one spring is more affected by gravity. Share this with me.

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This is a website with games that demonstrate gravity in some way. For extra credit, play a game and write one paragraph explaining how gravity is demonstrated in it.

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Gravity Games - Free Online Gravity Games

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We collected 27 of the best free online gravity games. Here we show you Cube Ninja, Run 3, Gravity Guy, and many more free games.

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Fill out this exit slip at the end of the lesson when directed.

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Gravity for Kids Fun is another article explaining gravity. This a good place to find ideas for your group demonstration.

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Gravity is the force that keeps us from floating off into space. It literally keeps our feet on the ground! We feel the effects of gravity every second of our lives (unless we're astronauts), but most of us don't give it a second thought. This article sets out to explain gravity for kids - and anyone else who has ever wondered why they fall down, rather than up.

(See more Science Articles.)

Before we get started, here's a question:
If I had a 1kg weight in one hand, and a 100g weight in the other hand, and dropped them at exactly the same time, which would fall the fastest and therefore land first?
You'll find the answer lower down the page!

Gravity For Kids: Introduction

Let's start at the beginning.

If you drop a stone, it falls to the floor. Why is this?

Everyone knows that the answer is 'Gravity'!
But what is gravity? It's more than just a word!
The real answer is that a force - a force we call gravity - is acting on the stone, and pulling it towards the Earth.

Gravity is, quite simply, a force of attraction between objects. The stone is 'attracted' to - pulled towards - the Earth.

Thanks to Isaac Newton, we know that:
The more mass an object has, the bigger the force of attraction.
And ...
The closer something is, the bigger the force of attraction.
The Earth, having a very large mass, and being very close, exerts a strong pull on anything in its vicinity, including:

a stone when you drop it,

your body when you fall over,

and something large and round flying above your head ...

... The moon!
But why doesn't the moon come crashing into the Earth? And why didn't Neil Armstrong come falling towards the Earth when he took his 'small step for a man'?
We'll get to that. But first we're going to take a look at how we came to understand gravity.

The Discovery of Gravity

Back to the question from the top of the page:
If I had a 1kg weight in one hand, and a 100g weight in the other hand, and dropped them at exactly the same time, which would fall the fastest ... and therefore land first?
The answer (which I hope you got right) is that they would both fall at the same speed (or, more specifically, with the same acceleration), and both would hit the ground at the same time.

Don't worry if you got it wrong. Even Aristotle (who lived from 384 to 322 BC) believed that heavier objects fall faster than lighter objects, so you're in good company!

In fact, most people believed this until around 1638, when Italian astronomer Galileo Galilei proved that objects fall at the same speed - whatever their weight (or, strictly speaking, their mass. See this article to find out the difference).

Note: An astronomer is someone who studies 'celestial bodies', such as moons, stars, planets, comets and galaxies.

Another note: We refer to Galileo Galilei by his first name, for the very good reason that that was how he referred to himself, as was the custom in Italy at the time.

The story goes that Galileo proved his theory by dropping different-sized balls from the leaning tower of Pisa.

He found that the speed at which an object falls is determined not by how heavy it is, but by how long it has been falling.

Galileo's Experiment Repeated ... On The Moon!

In 1971 astronaut Dave Scott performed a similar experiment to Galileo's. Not from the leaning tower of Pisa, but on the moon. Scott dropped a feather and a hammer, and - surprise, surprise -both reached the surface of the moon at the same time.

Galileo calculated the rate at which objects accelerate while falling to Earth. That rate is now known to be 9.81 m/s² - although this figure changes slightly depending on whereabouts on Earth it is measured.

The figure also ignores the effects of air resistance and any other factors which may create anything other than a perfect, frictionless fall.

Galileo increased our understanding of gravity, but even he couldn't explain why it was that things fell to the ground in the first place.

Isaac Newton

It was up to Englishman Isaac Newton - arguably the greatest scientist who ever lived - to realise what gravity actually was.

Like all scientists, Newton used the work of other scientists as a basis for his own theories.

German astronomer Johannes Kepler had worked out the rotation of the planets round the sun (using observations made by Danish astronomer Tycho Brahe).

Using Kepler's laws of planetary motion, Newton realised that gravity was a force of attraction, and the size of the force depended both on the mass of the objects involved, and the distance they were from each other.

Newton's Law Of Universal Gravitation

Newton's law of universal gravitation, published in 1687 states that 'any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them'.

The law can be written as an equation:

F = G ((m1xm2) / r²).

The force (F) between two objects of masses m1 and m2 is equal to the product of their masses divided by the square of the distance (r) between them.
G is the gravitational constant. It remains the same wherever it is applied in the Universe.
Using Newton's laws, we can find out why two objects of different mass fall with the same acceleration.

Basically, if the mass of an object is doubled, the gravitational force is doubled, but the rate of acceleration remains the same.

If the mass of an object is halved, then the gravitational force is halved, but again the rate of acceleration remains the same.

Using Maths to Find Planets

Using Newton's Law Of Universal Gravitation, scientists were able to calculate the presence of Neptune before it was 'properly' discovered.

In the 1820s it was found that Uranus (then the most distant discovered planet) was not where Newton's laws suggested it should be.

Over the next decades, astronomers in England and France independently concluded that Uranus's movement was being affected by another, unknown, planet, and calculated where this other planet would appear. This planet was Neptune, and it was found in 1846, proving that Newson's law was correct.

It was Neptune's gravitational pull that was affecting the orbit of Uranus.

Gravity, The Moon, And Tides

We've found that gravity is the force of attraction between two objects.

Every particle of matter is attracted to every other particle in the galaxy, but the force exerted between individual particles is very small, because their mass is very small.

But with large objects, such as the moon and the Earth, the force of attraction is very strong.

So strong, in fact, that it's enough to keep the moon spinning around the Earth, rather than flying off into space.

(The mass of the Earth is around 6 million million million million kg.)

Because the moon is smaller, and less dense, than Earth, it has a significantly smaller mass. Therefore the force of gravity on the moon is much smaller. Around 17% of the Earth's, in fact.

Neil Armstrong's weight on the moon was only 17% of what it was on Earth. This enabled him to jump higher than he could on Earth, but was still enough to bring him back to the Moon's surface.

Although the mass of the moon is much less than that of Earth's, it still affects the Earth. The force it exerts as it orbits the Earth pulls the oceans towards it, causing tides.

Gravity For Kids Conclusion

We've covered a lot in this article. Thanks to Galileo you've found that all objects (a stone, you, a grand piano) fall at the same rate, no matter what their mass.

Again, thanks to Galileo, you've found that on Earth, objects accelerate at 9.81 m/s² (give or take) when dropped, and that this figure varies ever so slightly depending on where you are on the Earth.

Newton's work showed us that gravity is a force of attraction between objects, and is dependent both on the masses of the objects involved, and on the distance they are from each other.

From this you know that the force of attraction increases for an object with more mass, and decreases for an object with less mass, meaning that their acceleration is a constant, G.

We've found that the moon is responsible for pulling the seas towards it, making the tides go out and come back in again.

Why not read more about the lives and work of the scientists in the article? Many of them made other incredible discoveries that were not just related to gravity.

See more science articles here.

Related pages:

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Gravity For Kids Fun, Clear Explanation With Pictures & Video

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Gravity is the force that keeps us from floating off into space. It literally keeps our feet on the ground! We feel the effects of gravity every second of our lives (unless we're astronauts), but most of us don't give it a second thought.

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This article is from the NASA website and explains some more about gravity! Click to read!

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Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.

What else does gravity do?

Why do you land on the ground when you jump up instead of floating off into space? Why do things fall down when you throw them or drop them? The answer is gravity: an invisible force that pulls objects toward each other. Earth's gravity is what keeps you on the ground and what makes things fall.

Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.

Earth's gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That's what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here.

You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force doesn't really have an effect on our planet.

Gravity in our universe

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made.

Gravity not only pulls on mass but also on light. Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You can't see the change with your eyes, but scientists can measure it.

Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping.

Gravity on Earth

Gravity is very important to us. We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breathe. Gravity is what holds our world together.

However, gravity isn't the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass. NASA uses two spacecraft to measure these variations in Earth's gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment (GRACE) mission.

GRACE detects tiny changes in gravity over time. These changes have revealed important details about our planet. For example, GRACE monitors changes in sea level and can detect changes in Earth's crust brought on by earthquakes.

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Gravity is the force by which a planet or other body draws objects toward its center.

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This is a video expplaining gravity AND the experiment that we’ll do later on.