An example of a rigid system is a stick under normal conditions.
In physics and engineering, a rigid system or rigid body is an idealized solid body in which deformation is zero or so small it can be neglected. In simpler terms, the distance between any two given points of a rigid body remains constant in time regardless of external forces acting upon it.
Understanding Rigid Systems
While perfectly rigid systems don't exist in reality (all materials deform under stress), the concept is useful for simplifying analysis in mechanics. Real-world objects are often treated as rigid bodies when their deformation is insignificant compared to their overall motion or size.
A Stick as an Example
As described in the reference: "A stick has a mass that does not deform under normal conditions. Although it is possible to deform the mass with extreme forces, under normal conditions the stick will not deform."
This property of not deforming under typical forces makes a stick a practical example of a rigid system in everyday scenarios. When you pick up a stick, its shape and size don't change noticeably under its own weight or from the force of your hand.
Characteristics of Rigid Systems (in ideal models)
- Fixed Shape and Size: The overall form of the system remains constant.
- Constant Distance: The distance between any two points within the system does not change.
- No Internal Deformation: The material does not stretch, compress, or bend internally.
Rigid vs. Deformable Systems
Here's a simple comparison:
| Feature | Rigid System (Example: A Stick under normal conditions) | Deformable System (Example: A Rubber Band) |
|---|---|---|
| Shape Change | No significant change under normal forces | Changes shape easily under force |
| Internal Distances | Remain constant | Can change (stretch, compress) |
| Analysis | Simpler; focuses on motion (translation, rotation) | More complex; involves material properties |
Other Practical Examples (Approximations)
In many practical situations, various objects can be approximated as rigid systems:
- A metal beam in a building structure
- A bowling ball rolling down a lane
- A brick wall
- The wheel of a moving car (for analyzing its rotation)
These examples, like the stick, maintain their shape and size under the forces they typically encounter, allowing them to be modeled effectively as rigid systems for analysis.
