What are Non-Contact Forces?
These forces can exert a push or pull even from a distance, without touching the object.
1. Magnetic Force
A magnet can attract iron objects or repel other magnets without touching them.
- Attraction: Unlike poles (North-South) pull each other.
- Repulsion: Like poles (North-North) push each other away.
2. Electrostatic Force
The force exerted by a charged body on another charged or uncharged body.
- Experiment: Rub a plastic straw with paper/polythene. It acquires an electric charge. It can now attract small pieces of paper.
- Rule:
- Like charges repel (+ and +).
- Unlike charges attract (+ and -).
3. Gravitational Force (Gravity)
Why does an apple fall down? Because the Earth pulls it.
- Definition: The force of attraction between any two objects in the universe.
- On Earth: The Earth pulls everything towards its center. This pull is called the Force of Gravity.
- Nature: Gravity is always attractive. It never repels.