The key difference between stiffness and rigidity lies in the type of forces they describe resistance to. Stiffness refers to the elastic properties of an object under multiple forces, while rigidity specifically addresses the elastic properties under shear forces.
Here's a breakdown:
Stiffness vs. Rigidity: A Detailed Comparison
| Feature | Stiffness | Rigidity |
|---|---|---|
| Definition | Resistance to deformation under multiple forces. | Resistance to deformation under shear forces. |
| Forces | Tensile, Compression, Shear, Torsional | Shear |
| Scope | Broader; encompasses various types of forces | Narrower; specifically addresses shear forces |
In essence, think of it this way:
- Stiffness is how much an object resists bending, stretching, twisting, or compressing.
- Rigidity is specifically how much an object resists being sheared or deformed sideways (think of pushing a deck of cards from the side).
Therefore, rigidity is a subset of stiffness; it is the stiffness of an object under shear forces. Stiffness is a more general term.
