📖 Chapter 4 of 12 · Mysterious Space- Basic 2 · Class 7
Chapter 3: What Is Gravity?
What is gravity?
Gravity is an invisible pull. The Earth pulls everything towards its centre — that is why a ball comes down when you throw it up, why rivers flow downhill, and why we stay on the ground instead of floating away. Everything with size has some gravity, but the Earth is so large that its pull is strong.
Gravity reaches into space
Gravity does not stop at the sky. The Earth's pull reaches all the way to the Moon and keeps it travelling around us, instead of drifting away. In the same way, the Sun's much greater gravity holds all eight planets in their paths. Gravity is the invisible thread that holds the Solar System together.
Story Time — The Question Under the Tree
Rohan · Amritsar, Punjab
Rohan was resting under a tree in his grandfather's orchard in Amritsar when an apple dropped and landed softly beside him. He picked it up and, half-joking, asked, “Why do apples always fall down? Why never up, or sideways?”
His grandfather, reading nearby, lowered his book. “That very question,” he said, “was asked long ago by a scientist named Isaac Newton, who also sat beneath an apple tree. He wondered the same thing, and it led him to a great idea.”
“What idea?” asked Rohan. “That the Earth pulls everything towards itself,” his grandfather said. “We call that pull gravity. It is invisible, but it is always working. It pulls the apple down, it pulls the rain down, and it keeps your feet on the ground.”
Rohan tossed the apple up and caught it as it fell. “So the Earth is pulling this apple down every time?” “Every time,” his grandfather said. “And here is the wonderful part. The same pull reaches all the way up to the Moon and keeps it circling the Earth. The very force that drops your apple also holds the Moon in the sky.”
Rohan looked up at the pale daytime Moon, then down at the apple in his hand, and felt the connection between them. “The same invisible pull,” he murmured, “for the apple and the Moon.” It was, he thought, the most amazing idea he had ever heard while sitting still under a tree.
Story Time — The Astronaut Who Did Not Fall
Ananya · Hyderabad
Ananya, who dreamed of becoming an astronaut, was puzzled by a video she had watched. “If gravity pulls everything down,” she asked her teacher, “why do astronauts float in their spacecraft? Has gravity switched off up there?”
“A very good question,” her teacher said. “Gravity has not switched off. It is still pulling the astronauts — and the whole spacecraft — towards the Earth.” Ananya was confused. “Then why do they float?”
“Imagine you and a ball jump off a diving board together,” the teacher said. “As you both fall, the ball floats right beside you, because you are falling at exactly the same speed. Astronauts float for a similar reason: they and their spacecraft are falling around the Earth together, at the same speed. Inside, they seem to float.”
Ananya thought hard. “So they are not beyond gravity — they are falling with their spaceship, and that is why everything drifts?” “Exactly,” her teacher said. “Gravity is still there. In fact, it is gravity that keeps their spacecraft circling the Earth instead of flying off into space.”
Ananya added a new line to her astronaut notebook: “In space you do not escape gravity — you learn to fall gracefully.” She liked that idea very much, and it made her want to visit space even more.
Solved Examples
Think first, then read the answer.
1. What is gravity?
Show answer
Answer: Gravity is an invisible pull. The Earth pulls everything towards its centre, which is why things fall down and why we stay on the ground.
2. Why does an apple fall down and not up?
Show answer
Answer: Because the Earth's gravity pulls it towards the ground.
3. What keeps the Moon circling the Earth?
Show answer
Answer: The Earth's gravity reaches all the way to the Moon and holds it in its path.
4. Has gravity switched off for floating astronauts?
Show answer
Answer: No. Gravity is still pulling them. They float because they and their spacecraft are falling around the Earth together at the same speed.
5. What holds the eight planets around the Sun?
Show answer
Answer: The Sun's gravity, which is very strong, holds all the planets in their paths.
Check Your Understanding
A. Fill in the blanks
- Gravity is an invisible _______.
- The Earth pulls things towards its _______.
- Gravity keeps the _______ circling the Earth.
B. Write True or False
- Gravity pulls things down towards the Earth. ( ___ )
- Gravity switches off in space. ( ___ )
- The Sun's gravity holds the planets. ( ___ )
C. Choose the correct word
- An apple falls (up / down).
- Astronauts float because they are (falling / flying) with their spacecraft.
D. Think and answer
- Name two things gravity does that you can see every day.
- Why do astronauts appear to float?
- What might happen if the Earth had no gravity?
Check your understanding
Tap an answer to see if it is correct. This is just for fun — nothing is saved.
1. What is gravity?
- A kind of light
- An invisible pull
- A type of gas
Show answer
B. An invisible pull
2. What keeps the Moon circling the Earth?
- The Earth's gravity
- The wind
- The Sun's heat
Show answer
A. The Earth's gravity
3. Why do astronauts float in a spacecraft?
- Gravity is off
- They fall around the Earth with their craft
- They are very light
Show answer
B. They fall around the Earth with their craft