![]() |
Circular Motion is defined as the movement of an object rotating along a circular path. Objects in a circular motion can be performing either uniform or non-uniform circular motion. Motion of a car on a bank road, the motion of a bike well of death, etc. are examples of circular motion. In this article, we will learn about circular motion and some related concepts, such as examples, equations, applications, etc. Table of Content What is Circular Motion?When any object moves in a circular path, it is said to be in circular motion. For example, when a car moves around a circular track at some speed, when the hands of the analog clock are moving, or when you swing an object tied with a rope in a circular path. In all the examples of circular motion, you will generally encounter an object that will be moving at some speed (constant or varying) around a circular path. Generally, the objects tend to move in a straight motion when you apply some force. But for an object to move in a circular motion, there must be some force acting on the object continuously which will turn the object towards the center of the circular path so that the object changes its direction continuously and thus forms a circular motion. Circular Motion DefinitionIn physics, circular motion can be defined as the motion in which an object moves when it follows a circular path. In circular motion the object generally moves around a fixed point and the distance between the object and the fixed point is generally fixed. Circular Motion ExampleThere are many examples of circular motion which you have already encountered in your life. Example 1: When you watch the hands of the analog clock moving in a clockwise direction, you will find that the hands are already moving in circular motion. Although it might look like the hands are actually rotating but when you will trace the motion of the tip of the hands, you will find that they are in circular motion. (We will further discuss the difference between rotational motion and circular motion in this article.) Example 2: When you tie a stone with a rope and swung it in a circular motion (Kindly check your environment before doing this experiment as this may hurt someone). Example 3: You must have heard that the electrons orbits in a circular path around a fixed nucleus in Bohr’s Atomic model. This also constitutes the example of circular motion as the electrons are going along a circular path (in Bohr’s Atomic model). Circular Motion in Real LifeThere are also situations where you have encountered circular motion of an object in real life too. Example 1: When we go to some fair (carnival) and we want to ride the Ferris wheel. The pods of the Ferris wheel moves in a circular motion. Example 2: A car turning on a circular track is also an example of circular motion. Generally these curves are made at an angle known as banked road which helps to reduce the role of friction to the circular motion of the car (Don’t worry if you are not able to visualize this contribution of friction, we will help you visualize this later in this article). Example 3: In your home when your mother bakes the cake, she used to make the batter for the cake first. For making the batter for the cake she stirs the spoon in a circular motion, where the mixing spoon is follows a circular path equidistant from a central point. These real life examples helps us visualize the circular motion and we tend to conceptualize the concepts even better. Related Concepts to Circular MotionThere are various new terms which comes into the picture when we talk about circular motion. These new terms generally arises from the fact that in circular motion there is angle involved so the terms, such as, angular displacement, angular velocity, or angular acceleration. The image added below shows the Angular Velocity and others in an object performing circular motion. Let’s see these concepts one by one. Angular DisplacementAngular displacement can be defined as the measurement of the amount of rotation an object has gone through in a circular path. In circular motion, the object moves in a circular path, and angular displacement helps us observe the position of the object in a circular path. It can also be understood as the angle made by the position vector of the object between its final and initial position in the circular path. Angular displacement is a vector quantity. The SI unit of the angular displacement is radians. It is conventionally denoted as θ. The mathematical representation of angular displacement is, Angular Displacement(θ) = Arc Length/Radius Therefore,
Angular VelocityAngular velocity can be defined as the rate of change of angular displacement. It is analogous to the linear velocity as it is the rate of change of linear displacement. Angular velocity can also be understood as the rate at which an object moves in a circular path.
Mathematically, angular velocity can be represented as, Angular Velocity (ω) = dθ/dt We know from above that, θ = S/R Using Angular Displacement in above equation, ω = d/dt.(S/R) which gives, ω = 1/R.(dS/dt) Finally,
Angular AccelerationAngular acceleration can be defined as the rate of change of angular velocity. It can be understood as the measurement of how fast or slow the angular velocity of an object is changing on the circular path. When any object starts from rest and acquires motion in circular path, it is said to have angular acceleration working on it. For example, when the Ferris wheel starts from the rest and acquires the speed, then the pods of the Ferris wheel gains angular acceleration. When the angular velocity increases, then the angular acceleration is positive. But when the angular velocity decreases, the angular acceleration is negative, i.e., angular deceleration.
Angular acceleration can be represented as, Angular acceleration (α) = dω/dt We can substitute ω = v/R in above equation to get, α = d/dt (v/R) α = 1/R (dv/dt) = 1/R.(a) Since, rate of change of linear velocity is called linear acceleration, therefore, above equation can be written as,
Equations for Circular MotionAcceleration which an object faces in circular motion generally has two components:-
When the object moves in a circular path, it experiences two different acceleration which works for two different purposes. One acceleration provides the magnitude of acceleration to the object while the other one is responsible for its direction. The acceleration which is responsible for the magnitude is called as tangential acceleration or linear acceleration. The acceleration which is responsible for the direction of the object moving in a circular path is called radial acceleration or centripetal acceleration. Both the tangential and the centripetal acceleration are perpendicular to each other. Centripetal acceleration acts towards the centre of the circle and keeps the object in a circular path. This centripetal acceleration is further responsible for the Centripetal force. The normal reaction of this force is Centrifugal force which is equal in magnitude and opposite in direction to the centripetal force. As we know the centripetal acceleration is given as, ac = V2/R. Since this acceleration is responsible for the centripetal force , therefore the centripetal force is given by, F = mac = mV2/R We also know from above that ω = V/R Putting the value of V from above in centripetal force, we get, F = mRω2 Since the object is moving in a circular path, the object must have taken some time to complete one full revolution. As we know that the time taken by the object to complete one full revolution is defined as its time period. It is denoted by T. A similar but slight different concept is frequency, which is the number of revolution made by the object in one second. Frequency is denoted by ν. ν = 1/T In a complete revolution, the object will move a distance of S = 2πR. Therefore, we will have V = 2πR/T In terms of frequency we can write V = 2πRν. The angular velocity can be written as, ω=2πν. The centripetal acceleration can be written as, ac = 4π2ν2R Centripetal ForceCentripetal force is the force which causes any object to undergo in the circular motion. This force is actually responsible for the motion of the object in the circular path.
Centripetal force in terms of time period T is given by, FC = 4mπ2R/T2. Centrifugal ForceNow lets talk about Centrifugal force. Have you been in a car when it is moving on a curve or circular path. You must have feel an outward sensation when the car moves in circular motion. While the car is moving in the circular path due to the centripetal force, what you were experiencing was actually the centrifugal force. Centrifugal force is actually a pseudo force (not a real force) which is experienced by the object when it is moving in a circular motion. It acts in the outward direction of the circular motion. Centrifugal force is observed in the non-inertial frame of reference. The magnitude of the centrifugal force is equal and opposite in direction to the centripetal force. That’s why it is considered as the normal reaction of the the centripetal force. Centrifugal force in terms of terms of linear velocity is given by,
Applications of Centripetal Force and Centrifugal ForceApplications of centripetal force and centrifugal force are observed in our daily lives are, Centripetal Force
![]() Centripetal Force Examples Centrifugal Force
Types of Circular MotionCircular motion can be classified into various types based on various factors. In context of physics and mechanics the object can be in circular motion in many different situations. Some common types includes:-
But here we will learn only about, two types of circular motion, i.e., uniform circular motion and non-uniform circular motion. Uniform Circular MotionWhen any object moves in a circular path at some constant speed then we say that the object is in uniform circular motion. Their is no change in the speed of the object and hence there is no acceleration produced. However, it is to be noted that the object is moving in a circular direction and the direction of the object is changing at every point of the path. Hence the centripetal acceleration is applying on the object at every point. This acceleration is inward in direction. But the tangential or linear acceleration is zero as the linear velocity is same. Let’s look at some examples now. Uniform Circular Motion ExamplesUniform circular motion has many examples which can be seen around us in everyday life. In these examples the speed is constant which results in stable angular velocity. Such examples are discussed below:
Acceleration in Uniform Circular MotionCentripetal Acceleration can be written in terms of linear velocity of the object and the radius of the circular path, and is given by,
Centripetal acceleration is inversely proportional to the radius of the circular path, which means as the radius of the path decreases the centripetal acceleration increases and vice versa. Non-Uniform Circular MotionWhen the object moves in the circular path along a fixed central point at changing speed, more specifically when the magnitude of the velocity changes over a particular period of time, then the object is said to be in non-uniform circular motion. The change in velocity can have implication on radius in non-uniform circular motion as change in velocity can bring the change in the radius of the system of the circular path on which the object is moving. Let’s look at some examples now. Examples of Non-Uniform Circular MotionExamples of non-uniform circular motion shows change in speed, and angular velocity which results in varied motion of the object along the circular path. These examples show changing velocity over time, either increasing or decreasing. Such examples include,
Acceleration in Non-Uniform Circular MotionIn non-uniform circular motion, as the speed or the angular velocity of the object changes, it experiences both the acceleration. Therefore, the acceleration in non-uniform circular motion has two components, i.e., the tangential acceleration as well as the centripetal acceleration.
Application of Circular MotionApplication of circular motion can be found in our everyday life as well as in practical situations. Various application includes, Turning of Vehicles at Banked RoadAs we know that the centripetal force which is directed towards the centre of a vehicle moving at a circular road is given by, FC = mV2/R. This force is provided by the force of friction which is between the tyre of the vehicle and the surface of the road. Note that it is the static friction which provides the centripetal force. Suppose the static frictional coefficient is μS and R is the radius of the circular road. Then the maximum speed at which the vehicle can drive at the circular flat road is given by, Vmax = √(μSRg) As the velocity of the vehicle is dependent on the μs and R, and the radius is generally not changeable. We can reduce the contribution of the static friction on the vehicle in a circular motion if we can make the road banked at an angle. Let the angle at which the road is banked be θ. As the vertical component has no acceleration part, its net force must be zero, therefore, N cosθ = mg + Fsinθ Horizontal component is solely responsible for the centripetal force acting on the vehicle, therefore, Nsinθ + Fcosθ = mv2/R Since F is less than μsN. Therefore, in order to have the maximum velocity, we have to put, FS = μsN Therefore, the equation of the vertical components will become, N cosθ = mg + μsNsinθ And Horizontal component will become, Nsinθ + μsNcosθ = mv2/R From vertical component, we can get the value of N to be, Putting this value of N in horizontal component, we get, Rearranging the term and dividing the left hand side of the equation with cosθ, we get Vmax to be, Comparing this maximum speed with the maximum speed of the vehicle at the flat road, we can clearly see that this term has some other part in the equation which increases the maximum speed with which the vehicle can move at a banked road in a circular motion. Differences Between Uniform and Non-Uniform Circular MotionBelow is listed a table to differentiate between uniform circular motion and non-uniform circular motion.
Circular Motion and Rotational MotionBelow table highlights the difference between the circular motion and the rotational motion.
Circular Motion FormulasCircular Motion formulas are added in the table below,
Learn More, Circular Motion – Solved ExamplesExample 1: Find the angular velocity of the boy who is riding the bicycle at a speed of 10 ms-1 on a circular path of radius 25 m. Solution:
Example 2: In the above problem, if the mass of the boy is 35 kg then calculate the centripetal acceleration of the boy and also find the centrifugal force acting on the boy. Solution:
Example 3: Suppose a motorcyclist is making a turn at a speed of 10 ms-2. How will the force acting towards the centre will change if he doubles its speed? Solution:
Example 4: A car is going in a non-uniform motion on curve of circular path, and its tangential acceleration is given as 3 ms-2, while its centripetal acceleration is given as 4 ms-2. Calculate its total acceleration. Solution:
Example 5: An insect is trapped in a circular groove of radius 10 cm moves along the groove steadily and completes 5 revolutions in 100 seconds. What is the angular speed and linear speed of the motion? Solution:
Circular Motion – NumericalsQ1: A boy with a mass of 25 kg is rides his cycle in a circular path at a speed of 2.5 ms-1. If the radius of the circular path is 2.5 m, then calculate the centripetal acceleration of the boy. Q2: A boy is riding a merry-go-round. If he completes 10 revolutions in 20 seconds. Calculate its angular velocity. Q3: A car of mass 500 kg is moving on a circular path of radius 150 m. The car is moving at a constant speed of 50 ms-1. How much force is required to keep the car in circular motion? Circular Motion-FAQs1. What is Called Circular Motion?
2. What is Uniform Circular Motion and Non-Uniform Circular Motion?
3. What is Relation Between Linear Speed and Angular Speed?
4. What is Relation between Linear Acceleration and Angular Acceleration?
5. What is Centripetal Force and Centrifugal Force?
6. What are Tangential Acceleration (at) and Centripetal Acceleration (ac)?
|
Reffered: https://www.geeksforgeeks.org
Class 11 |
Type: | Geek |
Category: | Coding |
Sub Category: | Tutorial |
Uploaded by: | Admin |
Views: | 17 |