Gravity is the force of attraction between any two objects that have mass . Every single thing in the universe — you, this page , every planet , every star — pulls on everything else with gravity . The more massive an object is and the closer you are to it, the stronger its gravitational pull .
✨ The English scientist Isaac Newton began developing his theory of gravity in the 1660s . The story of an apple falling from a tree may be exaggerated , but Newton really did use falling objects to think through how gravity works .
It is worth clearing up a common confusion between mass and weight . Mass is how much 'stuff' you are made of, and it never changes . Weight is how hard gravity pulls on that mass , so it changes from place to place . You have the same mass on Earth , the Moon , and Mars — but you would weigh different amounts on each, because their gravity is different .
Gravity is what keeps the planets orbiting the Sun, the Moon orbiting Earth , and satellites orbiting our planet . An orbit is a curved path caused by a balance between two things: the forward motion (speed ) of the orbiting object and the inward pull of gravity . If the speed is just right , the object curves around without spiralling in or flying away .
📷 NASA / Apollo 11 · Public domain🃏 Flip each card to test your gravity knowledge.
? What is gravity? A force of attraction between objects with mass
? Who described gravity's laws? Isaac Newton (and later Albert Einstein)
? Why do planets orbit the Sun? Gravity pulls them inward while their speed keeps them going around
? Why do we feel lighter on the Moon? The Moon is less massive than Earth, so its gravity is only 1/6 as strong
Tap each card to see the answer.
A clever way to picture an orbit comes from Newton himself . Imagine firing a cannon from a very high mountain . Fire gently , and the ball lands nearby . Fire harder , and it lands further away . Fire hard enough , and the ball curves around the whole planet and never lands — it is in orbit ! That is exactly how satellites stay up.
🔗 Match each gravity word to its meaning.
Falling freely, feeling weightless A curved path around another object How hard gravity pulls on an object How much 'stuff' an object is made of
Falling freely, feeling weightless A curved path around another object How hard gravity pulls on an object How much 'stuff' an object is made of
Falling freely, feeling weightless A curved path around another object How hard gravity pulls on an object How much 'stuff' an object is made of
Falling freely, feeling weightless A curved path around another object How hard gravity pulls on an object How much 'stuff' an object is made of
✨ On the Moon you would weigh only one-sixth of your Earth weight . If you weigh 30 kg here, you would weigh just 5 kg on the Moon — and you could jump six times as high !
📷 jurvetson · CC BY 2.0Albert Einstein showed in 1915 that gravity is not just a force — it is actually a curvature of space itself . Massive objects like stars bend the fabric of space around them, and planets follow these curves . This idea , called General Relativity , is one of the most important in all of science , and it has been confirmed many times by experiments and observations .
💡 Imagine stretching a rubber sheet and placing a heavy ball in the centre — the sheet dips . A smaller ball rolled near the heavy one curves towards it, following the slope . That is a simple way to picture how a massive object bends space .
🗂️ Sort each example into caused by gravity or not caused by gravity.
A ball falling to the ground
? Caused by gravity Not caused by gravity
Caused by gravity Not caused by gravity
A magnet attracting iron filings
? Caused by gravity Not caused by gravity
Caused by gravity Not caused by gravity
Caused by gravity Not caused by gravity
Gravity even shapes the largest things in existence . It pulled together the gas that formed the Sun and planets , it holds billions of stars together in galaxies , and at the extreme it creates black holes . From an apple falling to the birth of galaxies , the same simple force is at work everywhere .
📷 NASA · Public domain✍️ Fill in the gravity facts.
How much 'stuff' you are made of is your _____ , and it never changes . How hard gravity pulls on you is your _____ , which changes from world to world . A curved path around another object is called an _____ .
mass weight orbit force speed
