Concepts of rotational motion

Concepts of rotational motion

Introduction

The concept of rotational motion is a very important concept in physics. It has many applications in our day-to-day lives. In this article, we will discuss the basic concept of rotational motion. We will also look at practical examples of rotational motion.

What does rotational motion entail?

When a body is pivoted at a point, and a force is applied to it at a suitable location, the body rotates around the axis that passes through the pivotal point. This is the force’s turning effect, and the body’s motion is known as rotational motion. Rotational motion can be found in almost everything: every machine, celestial body, and the majority of amusement park rides. 

Examples of rotational motion

1. In our daily lives, we see examples of rotational motion. Day and night cycles are created by the earth’s rotation about its axis.
2. The rotatory motion of the helicopter blades is also rotatory motion.
3. A door that opens and closes by swivelling on its hinges.
4. A Ferris wheel in an amusement park with a spinning top.

Objects rotate around a central axis. The motions of all the particles and the mass centre are not the same. All of the body’s particles move in the same direction. It is, by definition, necessary for us to investigate how the various particles of a rigid body move when the body rotates.

Kinematics of Rotation

In rotational kinematics, we’ll look at the relationship between rotational kinematical parameters. We’ll go over the angular equivalents of the linear quantities such as position, displacement, velocity, and acceleration.

A case of constant angular acceleration is crucial, and a parallel set of equations applies in this case.

Equations of Rotational motion

The equations of rotational motion are given below.

• ω = ω० + αt
• θ = ω०t + 1/2 αt2
• ω2 = ω०2 + 2αθ

Rotational Motion: Characteristics

A rigid body’s particles follow a circular path around the rotational axis in rotational motion. The rotational axis can be fixed or unfixed. The rotation of a fan is an example of rotational motion about a fixed axis, in which each particle on the blade follows a circular path around the axle of the fan’s motor. A spinning top is an example of rotational motion about an unfixed axis. The tip of the top is an unfixed axis around which all the particles follow a circular path.

Rotational Axis

The axis of rotation is a rigid body of any shape rotating around a fixed axis (the axis that does not move). By definition, we must investigate how the various particles of a rigid body move when the body is rotated.

This category includes activities such as rolling. Due to the increase in the number of automobiles and other rolling vehicles, rolling wheels and wheel-like objects are arguably the essential application of rotational physics. The rolling motion of a round-shaped body placed on a surface can be a combination of translational and rotational motion. When a body is moving in a rolling motion, each particle has two velocities: one due to rotational motion and the other due to translational motion (of the centre of mass). The resultant effect is the resultant of both velocities in the tiniest particles.

Types of motion involving rotation

1. Rotation around a central axis: This includes the rotation of the ceiling fan, the potter’s wheel, the opening and closing of doors, the rotation of the clock hands on the wall, and so on. When the ceiling fan rotates, the vertical rod from which it is suspended remains stationary while its blades move in a circular path.
2. Rotation around the translational axis stimulates a wide range of motion. This type of motion includes things like return motion. Consider the wheel speed of a vehicle travelling on a straight, flat road compared to the speed of a guide system moving alongside the vehicle.

The wheel appears to be rotating around a stationary axle. With the guide system attached to the ground, the wheel will rotate around a moving axle. As a result, the wheel’s returning speed results from the superposition of two separate motions that occur at the same time. 

3. Rotation around a central axis: The object rotates around one axis, which revolves around another axis in this motion. 

Did you know?

A two-dimensional object rotates around a rotational centre (or point). An axis is a line that rotates a three-dimensional object. The object’s body is said to rotate upon itself or spin if the axis of rotation is within the object’s body. Spin refers to the relative speed and possibly free movement with angular momentum. An orbit, or more precisely an orbital revolution, is a circular motion around an external point.