Question

Determine if a real-world system could be represented as a rigid body

I just need an exemple

Answer 1

REAL WORLD SYSTEM REPRESENTED AS A RIGID BODY – JUSTIFY.
The system of real world very much advanced and something voluminous with higher range of complicated data. The system might just seem difficult to address to explain as such as a single entity, but when it is broken into basic components of our day-to-day usage, we can find our reasoning logical and easily understandable. For the purpose of understanding the stated problem with regards to rigid bodies, let’s take common example
Before starting with examples lets first understand what real rigid body means in science and engineering terms actually. First of all, let’s understand difference between solid body and a rigid body. All bodies which has a definite shape with relatively intact particles to one another can be termed as solids in practical life, whereas a rigid body is a body or material whose distance between two particles are same with reference two some arbitrary reference point. The solids are practically varying in particle level as we all know there is always minimal space between them at microscope level. The rigid bodies in other hand are not real, they are conceptual, with their unchanged positioned maintained with reference that reference point mostly named as origin in common terms.
As stated above the rigid bodies as such cannot exist in real world, but the conceptual meaning still makes its existence possible in the world. The engineering or science definition states rigid body as a solid body but its distance between any two points remain constant or with negligibly small displacements in time regardless of exerted external force.
For state of understanding the conceptual reality of rigid body, let us consider a vehicle whose relative to its body remains similar without change in view of the road on which it journeys. In this example of real life, we know the vehicle (Fig. 1) whatever it is happen to undergo minute change with regard to particles it faces on road, but all those being very minute forces, they can be neglected. Upon this neglection, the vehicle becomes a rigid body as such with reference to entire road with no variation in vehicle body. In same manner axle connecting the brake and brake drum remain rigid with regards to all its moving components (Fig.2).
For still better understanding, let us take very basic example of civil engineering. The frames holding windows or doors which is attached to structural system (Fig.3). In this example, the frame holds the panel or components without its movement. The frame remains rigid in context of nil movement regards to surrounding system but its finite disturbance within is neglected as it is infinitely small regard to entire system.