Why Do Things Fall Down?

What You'll Learn

• Gravity is an invisible force that pulls things toward Earth's center
• Everything with mass has gravity — even you!
• Earth's gravity is what keeps us on the ground and makes things fall
• Gravity pulls everything at the same speed — heavy and light things fall together
• Without gravity, everything would float away into space

Words to Know

Gravity

An invisible force that pulls things toward each other

"Gravity pulls things down to Earth."

Mass

How much stuff is inside something

"The Earth has a lot of mass."

Force

A push or a pull

"Gravity is a pulling force."

Float

To drift without falling

"Without gravity, we'd float away."

Check What You Learned

Fun Facts

• Gravity is a force that attracts objects with mass toward each other

  Source: NASA

• Earth's gravity pulls everything toward its center at 9.8 m/s^2

  Source: Physics textbooks

• Everything with mass has gravity — even people — but small objects have negligible gravitational pull

  Source: Newton's Law of Universal Gravitation

• The Moon's gravity is about 1/6 of Earth's

  Source: NASA

• In a vacuum (no air resistance), all objects fall at the same rate regardless of mass

  Source: Galileo's principle, confirmed by Apollo 15 astronauts on the Moon

• Apollo 15 astronaut David Scott dropped a hammer and feather on the Moon — they hit the ground simultaneously

  Source: NASA Apollo 15 mission