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Linear Motion

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Introduction to Linear Motion

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Whenever we speak about motion or rest it is always explained with reference to some fixed point which is known as the origin. So, with respect to the change in the position, we have two quantities that can be used to describe any change in the position and they are distance and displacement. The distance can be defined as the total path covered during the motion. It can be represented by a magnitude only. While displacement can be defined as the shortest distance between the initial and final position. It requires both the magnitude and direction for complete representation.


Our daily activities including walking, running, etc. involve linear movement. There is a change in the position of the object involved in these activities. Some examples of motion are: 


Fish swimming in the water,  dropping of stone from a certain height, the flow of air which is coming in and out of our lungs, the automobiles carrying passengers from one place of pick up to the destination is also an example of motion. As we can notice that different objects move in different ways. Some objects move in a curved path while some in a straight path and a few others in a zig-zag way. Depending on the path taken by the particle the motion can be classified as projectile motion, rectilinear motion, rotational motion, and many more. In this topic, we have discussed the linear motion definition, let’s understand more about classification.

With Respect to the Nature of the Movement, Motion is Classified Into Three Types as Follows:

  • Linear Motion

  • Rotary Motion

  • Oscillatory Motion


What is Linear Motion?

Linear motion meaning the change of position of an object with respect to time interval. We live in a universe that is in continuous motion. The fundamental particle of a matter i.e. atom is also in constant motion. Every physical process happening in the universe is composed of some sort of motion. The motion can either be fast or slow, but motion always exists.  Motion is described in terms of the following terms: Distance, Displacement, Speed, and Time as discussed above.


In general, a body will be said to be in motion if it changes its position with respect to a reference point and time. While describing the Linear Motion we require only one coordinate axis along with time to describe the motion of a particle then it is said to be in linear motion or rectilinear motion. In linear motion, the particles will move from one point to another point either in a straight line or a curved path. Depending on the path of motion linear motion is further subdivided divided as:

  • Rectilinear Motion – It is a path of motion in a straight line.

  • Curvilinear Motion – It is a path of motion in a curved line.


Types of Linear Motion

An object is in a linear motion if the object moves in a straight line, on the other hand, an object is in a rectilinear motion if two objects move in a straight line and are parallel to each other. The two types of linear motion are uniform motion and non-uniform motion but the three types of rectilinear motion are uniform rectilinear motion, uniformly accelerated rectilinear motion and rectilinear movement with non-uniform acceleration.

  • Uniform Linear Motion: When an object travels at a constant speed with zero acceleration.

  • Non-Uniform Linear Motion: When an object travels at an irregular speed and acceleration. 

In this topic we have discussed what is meant by linear motion, let’s understand Rotary motion and Oscillatory motion also.


Rotatory Motion

In the above topic, we have discussed linear movement definition, rotary motion is the type of motion occurring when a body rotates on its own axis. The most common example of rotatory motion is the Spinning wheel and the motion of the earth around the sun about its own axis.

When we drive a car, the motion of wheels and the steering wheel about its own axis is also considered as Rotary motion.


Oscillatory Motion

We have discussed what linear motion is, let’s know about Oscillatory motion. It is the type of motion in which a body moves around its mean position. Some examples of oscillatory motion are: The pendulum of a clock is in oscillatory motion as it moves to and fro about its mean position. The string of the guitar when strummed also moves to and fro about its mean position which results in an oscillatory motion.


Conclusion

In this article, we have discussed Motion and different types of motion are also discussed. Types of Linear motion along with Rotary motion and Oscillatory motion are also described. Below are some examples to have a clear understanding of uniform motion and nonuniform motion.


Eg: If a car is travelling at a speed of 50 km/hour then it will cover a distance of 1 km/minute. In this sense, the motion of car acceleration is uniform.


A boy after kicking a football. It may cover 5 meters in the first attempt, 10 meters in the second change, 6 meters in the third attempt, and so on as per the velocity exerted by the boy.

FAQ (Frequently Asked Questions)

Question1: Linear Motion Definition and How is It different from Circular Motion?

Answer: Linear motion physics is also known as rectilinear motion. It is a motion on a straight line in one dimension. When an object travels in a straight line it changes its position along with the time taken. On the other hand, circular motion is an object’s movement across a circle or movement in a circular direction. It has a rotation along a fixed axis of the object which is three-dimensional and involves circular motion of all its parts.

Question2: Define Linear Motion With Example.

Answer: Linear motion is a type of motion on a straight line in one dimension. When an object travels in a straight line it changes its position along with the time taken. An example of Linear motion is: Falling of stone from a certain height, an athlete running 200 m on a straight track, train running in a straight track, car moving at a constant speed.

Question3: What is the Difference Between Linear Motion and Rectilinear Motion?

Answer: An object is in a linear motion if the object moves in a straight line, on the other hand, An object is in a rectilinear motion if two objects are moving in a straight line and are parallel to each other. The two types of linear motion are uniform motion and non-uniform motion and three types of rectilinear motion are uniform rectilinear motion, uniformly accelerated rectilinear motion, and rectilinear movement with non-uniform acceleration.