Introduction to Linear Motion by Vedantu

Let us assume that you are reading a book sitting on your sofa,  now,  think whether you are in motion or at rest? Clearly,  here you are at rest. But let us try to re-evaluate the situation. We all live on this earth that is continuously moving,   so now,  are you in the state of motion or at rest? Well,   finding answers to this complex question can be slightly confusing but let us break down the concepts and  simply learn about  motion and its types.


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 Motion?

Motion is the free movement of a body with respect to time. It can be defined as a process of changing position. For example-a moving train,  a rotating fan,   a ball rolling around etc. Even though this universe is in continuous motion,   but,   there are different types of motion which will make your understanding more detailed and clear.


With respect to the nature of movement,  motion is mainly categorized into four different types:

  1. Rotatory Motion - this is a kind of motion in which the object rotates around a fixed axis. For example,  a rotating fan.

  2. Oscillatory Motion - in oscillatory motion an object repeats in the same motion continuously back and forth. For example,  a pendulum.

  3. Linear Motion - this motion is a one dimensional motion that takes place in a straight line. For example,  a train running on a track.

  4. Reciprocating Motion - this motion is a continuous up and down or back and forth motion. For example,   a gymnast swinging on a ring.


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. Basically,   in linear motion an object travels the same distance at the same time and the object can move in a straight or a curved path from one point to another. 


Depending on the path of motion linear motion is further subdivided as: 

  • Rectilinear Motion – It is a path of motion in a straight line. In this motion all particles travel the same distance following a parallel straight line.

  • Curvilinear Motion – It is a path of motion in a curved line. The orientation of the body in space does not change, but the trajectories of individual particles of the body are curved.


Types of Linear Motion:

  • Uniform Motion - a body said to be in uniform motion when it moves in a straight line at a constant speed. For example a car moving at a steady speed on a straight road. In a graphical representation uniform motion can be represented by a straight line.

  • Non-Uniform Motion - a body covers and equal distances in a set and given time intervals it is said to be in non uniform motion. In the graphical representation this motion can be represented as a curved line.


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.


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 traveling 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.

FAQs on Linear Motion

1.What causes linear motion?

Linear motion is a movement in a straight line. The angular motion of the joints that our body produces by applying force are then combined to form linear motion. The more linear  the motion,   the better is the performance of the swimmers,  ski jumpers,   sprinters or athletes etc. The performance will get better if the linear motion is maintained,  even if the motion is general.

2. Is linear and non-linear motion the same?

In linear motion net force is not required whereas non-linear  motion requires net force. A net force that is acting parallel to the movement of a body will cause a linear motion but when it is applied in a direction which is not parallel to the movement then it will cause non linear motion. Most of the motions encountered in our daily life are non-linear motion as there is always a change in direction. An object is always on acceleration when it is moving on a nonlinear path.

3. What is accelerating uniformly?

When the speed of an object is increasing at a constant rate then it is said to be accelerating uniformly. The rate of acceleration is always constant. If a car speeds up when it slows down and then again speeds up  it doesn't have uniform acceleration. For example,   a ball rolling down an inclined plane,   a bicycle going down the road,   the motion of a freely falling body,   a ball dropped from the top of a ladder and a vibrating spring in a sewing machine.

4. How is linear and rotatory motion created?

When the line of force passes through the center of mass of a body then direct force is applied resulting in linear motion and rotatory motion is caused when an object moves around a fixed axis without changing its radius. Examples of a linear motion is an athlete running 100m on a straight track  or falling off a stone from a certain height and the examples of rotatory motion can be a turning wheel or the blades of a fan etc. 

5. What are the two types of linear motion?

On thIs site of Vedantu we have discussed in detail about the meaning and types of linear motion. To get a detailed Insight on this topic kindly refer to the above article.  Linear motions  are of two types: rectilinear motion and curvilinear motion. In rectilinear motion the object moves in a straight line for example a stone falling freely from the top of the  building and in curvilinear motion objects move in a circular path  for example motion of earth around the sun.

6. Linear Motion Definition and How is It different from Circular Motion?

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.

7. Define Linear Motion With Example.

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.

8. What is the Difference Between Linear Motion and Rectilinear 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 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.

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