Gravity Cheat Sheet

Definition

Gravity is a force that pulls objects with mass or energy toward each other. The more mass an object has, the stronger its gravitational pull.

Example: The Earth's gravity pulls everything towards its center, which is why things fall down.

Gravity on Earth

On Earth, gravity accelerates objects at approximately 9.8 m/s² (meters per second squared). This is often rounded to 10 m/s² for simpler calculations.

Example: If you drop a ball, its speed increases by about 9.8 meters per second every second it falls.

Mass vs. Weight

Mass is the amount of matter in an object (measured in kilograms). Weight is the force of gravity on that mass (measured in Newtons).

Example: Your mass is the same on the Moon as on Earth, but your weight is less on the Moon because the Moon's gravity is weaker.

Inverse Square Law

The force of gravity decreases as the distance between objects increases. Specifically, it decreases with the square of the distance.

Example: If you double the distance between two objects, the gravitational force between them becomes four times weaker.

Formula (simplified)

Gravitational Force ≈ (mass1 * mass2) / (distance²). This shows that larger masses increase the force, and larger distances decrease it.

Example: A heavier planet will have a stronger gravitational pull than a lighter planet at the same distance.

Gravity in Space

Gravity keeps planets in orbit around the Sun, and moons in orbit around planets. Without gravity, these objects would fly off into space.

Example: The Earth orbits the Sun because of the Sun's strong gravitational pull.

Falling Objects

Gravity causes objects to accelerate downwards. Air resistance can slow down this acceleration.

Example: A feather falls slower than a rock because of air resistance.

Tides

The Moon's gravity pulls on the Earth's oceans, causing tides.

Example: High tide occurs when the Moon's gravity pulls the ocean water towards it.

Weightlessness

Astronauts in space appear weightless because they are constantly falling around the Earth. They are still affected by gravity, but they are in freefall.

Example: Astronauts float inside the International Space Station because both the station and the astronauts are falling around the Earth together.