Force
Procedure: Similar triangles
- Geometric triangles are similar to vector triangles
 
NCEE
1

Procedure: Deformed Lever
- Two balls balanced by three forces
 - Have a pair of internal forces (e.g., coulombic forces)
 - Another pair of forces crossed at one point, which is the fulcrum
 
NCEE

Procedure 3
Requirement: The resultant force of multiple forces is zero
If a force \( F \) is reversed, the resultant force after that is \( 2F \)