What is a Free Body Diagram?
In physics, we use diagrams to show all the forces acting on a single object. This helps us predict how the object will move.
Example 1: A Book on a Table
When a book rests on a table, it doesn’t move. Does that mean no forces are acting? No! It means the forces are balanced.
- Gravity: Pulls the book down.
- Reaction Force (Normal Force): The table pushes the book up.
- Result: They cancel each other out. Net force = 0.
Example 2: Pushing a Box
Imagine pushing a heavy box across the floor.
- Applied Force (Push): Acts in the direction of motion.
- Friction: Acts opposite to the direction of motion.
- Gravity: Pulls down.
- Reaction: Floor pushes up.
Key Rule: The box will only move if your Push > Friction.