# Rigid Body and Rigid Body Dynamics

## Introduction

The Rigid body can also be described as particles collection with the property where the distance between particles is unchanged at the time of course of motions of the body. The axis around which the body keeps rotating either in a circular path is called the axis of rotation. The dynamics and kinematics of rotation of a rigid body mainly take place around an axis. Here the axis that is fixed is determined to be fully analogous to those of linear motion along one fixed direction and is considered to be in the rotational motion.

## What is motion?

The situation when a body is determined to change its position and orientation constantly with time is considered to be in motion. If the orientation of the bodies keeps changing constantly with the time interval then it can be determined as the phenomenon of rotation (Huang et al. 2019).

The rigid bodies can be in different motions like the translational motion and the rotational motion. When a rigid body is travelling along a straight line then it is considered to be in translational motion. When a rigid body is found travelling along an inclined plane then it is considered to be in rotational motion.

## What do you mean by the rigid body?

The rigid body is determined as the body’s idealization that never changes its shape or does not deform. The force that is exerted on a rigid body then there will be a change in the state of body motion. If the force is exerted on a non-rigid body then the size and shape of the body will get changed. The rigid body has a well-defined unique equilibrium geometry, whereas the non-rigid body has no possible geometry of a unique equilibrium.

Figure 1: Rigid Body: Particle Chunks

All bodies get deformed when they are in motion. In the context of the rigid body there is no deformation is found and is determined as the constant distribution of mass (Li et al. 2018). This phenomenon can be further elaborated as when the distance between 2 provided points of the rigid body remains in the constant state in time interval even if an external force is exerted on that body.

## Types of the rigid body motions

The Rigid motion is considered to be the relative distance between the 2 points that remains the same. Here the relative position between the 2 points also remains equal. There are 4 main types of rigid body motions translational motion, reflectional motion, rotational motion, and glide reflection motion (Borisov et al. 2018). Examples of the rotational motion are the rotation of a ceiling fan and the rotation of the clock. For reflectional motion an echo is the major example, and for glide reflection motion is the footprint left by a person while walking on sand.

## What are the dynamics of the Rigid body?

In order to state the rigid body dynamics, it is vital to elaborate on the types of motion that a rigid body has. Those motions are the translational motion and rotational motion (farside.ph.utexas, 2022). If a rigid body is found in pure rotational motion then it will rotate around an axis that is fixed and perpendicular to a fixed plane. If a rigid body travels along the circular or curved plane then its centre of mass will remain in motion and the rigid body will be in rotational motion.

Figure 2: Rigid body rotation

The rigid body that is in rotational motion travels around an axis and the axis is determined as the axis of rotation. If a rigid body is found travelling along a straight line or even along a linear path then it can be determined as in its translational motion (Carpentier et al. 2018). There are two main types of translation motion that are Rectilinear motion, and Curvilinear motion.

## Conclusion

In a rigid body, all atoms always remain in the same position even if any force is applied from outside to the body. In a rigid body there is no deformation is found and is determined as the constant distribution of mass. Even if the rigid body has various mad molecules and atoms they will remain in the uniform motion state. There are two major types of the motions of the rigid body the rotational motion and the translational motion. Examples of translational motion are the moving of a car, skating of a plant by an individual, and sailing of a boat. Examples of the rotational motion are the motion of wheels, rotation of motors, and so on. The understanding of when the rigid body is rotational and when it is translational motion is determined as the rigid body dynamics.

## FAQs

Q1. What do you mean by rigidity of a rigid body?

Ans. The rigidity of the rigid body in accelerator physics is the effect of a specific field of magnet where many charged particles remain in motion. It is the measurement of particle momentum and refers to the fact that the particles with higher momentum has higher resistance and get deflected by a magnetic field.

Q2. What are the main characteristics of the rigid body?

Ans. Every line on the rigid body has an equal angular acceleration and angular velocity. The motion of the rigid body can get decomposed into translation of the arbitrary point and is followed by rotation about point.

Q3. What is the orientation of the Rigid body?

Ans. The orientation of a rigid body can get change or rotate when its centre of mass is stationary. The rotation of the rigid body can be tracked by 1 Quaternion, 3x3 Matrix, and also by 3 Euler angles.

Q4. What is the stimulation of the rigid body?

Ans. The rigid body stimulation can be utilized in order to stimulate the motion of solid particles. Stimulation basically affects the orientation and position of the particles and then never deforms them. The rigid body stimulation works with the system of animation.

Updated on: 13-Oct-2022

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