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💬 Think about it
When you push a table, the table also pushes back on your hand — stop pushing and that feeling vanishes. So is a force a lonely thing, or does it always need two objects? Let's find out, and meet the unit that measures force.
How many objects are needed for a force?
- When you push a table, your hand and the table interact.
- A force comes into play only when two objects interact.
- So at least two objects must interact for a force to act.
Example:
A bat hitting a ball is two objects interacting — the bat and the ball.
What is the definition and unit of force?
- A force is a push or pull on an object from its interaction with another object.
- The SI unit of force is the newton (small "n").
- Its symbol is N.
➡ A step further
- An object at rest does not mean no force acts on it.
- It means the forces on it are balancing one another.
- You will learn about balanced forces in higher grades.
➡ A step further
- When you push a table, your hand feels a force too.
- The moment you stop pushing, that force disappears.
- Whenever two objects interact, each feels a force from the other.
- When the interaction stops, the forces stop.
Important Definitions
- Force — A push or pull on an object resulting from its interaction with another object.
- Newton (N) — The SI unit of force.
