Gravity
Gravity pulls everything toward Earth's centre. That's why things fall down, not up.
Normal force
When something sits on a surface, the surface pushes back up on it with an equal force. That push is the 'normal force'.
Applied force
Any push or pull you give an object — pushing a swing, pulling a wagon — is an applied force.
🔑 Key Terms
- Force
- A push or pull.
- Gravity
- The force that pulls objects toward Earth.
- Normal force
- The push of a surface up on an object resting on it.
Did you know?
You'd weigh about 6 times less on the Moon — its gravity is much weaker than Earth's!
Try it at home: Drop test
- Drop a coin and a feather at the same time from the same height.
- Which lands first? (Air resistance affects the feather!)
- Now crumple a tissue and a flat tissue and drop them. What happens?