𝙃𝙚𝙡𝙡𝙤,𝘵𝘰 𝘢𝘭𝘭 𝘮𝘺 𝘨𝘭𝘰𝘳𝘪𝘰𝘶𝘴 𝘱𝘩𝘺𝘴𝘪𝘤𝘴 𝘭𝘰𝘷𝘦𝘳𝘴 , 𝙒𝙚𝙡𝙘𝙤𝙢𝙚! 𝘛𝘩𝘪𝘴 𝘪𝘴 𝘮𝘺 𝘧𝘪𝘳𝘴𝘵 𝘣𝘭𝘰𝘨 𝘱𝘰𝘴𝘵 𝘢𝘯𝘥 𝘪𝘯 𝘪𝘵 𝘸𝘦 𝘸𝘪𝘭𝘭 𝘥𝘪𝘴𝘤𝘶𝘴𝘴 𝘢 𝘭𝘪𝘵𝘵𝘭𝘦 𝘢𝘣𝘰𝘶𝘵 𝘬𝘪𝘯𝘦𝘮𝘢𝘵𝘪𝘤𝘴 .

kine means “𝐭𝐡𝐞 𝐦𝐨𝐭𝐢𝐨𝐧 ” And matics means ” 𝐌𝐚𝐭𝐡𝐬 “. Therefore in general it deals with the motion of objects.

Without making you feel bore lets talk abou rest and morion of objects.

But before knowing this keep one thing in a mind that —”𝙽𝚘𝚝𝚑𝚒𝚗𝚐 𝚒𝚜 𝚒𝚗 𝚘𝚋𝚜𝚘𝚕𝚞𝚝𝚎 𝚖𝚘𝚝𝚒𝚘𝚗 𝚘𝚛 𝚊𝚝 𝚛𝚎𝚜𝚝”.

Rest and motion…

So how we define when an object is in motion or at rest?

Basically when an object changes its position with time we say it is in motion, whereas when the position of object does not changes with time we considered it at rest.

The concept of rest and motion depends on both ‘observer’ and ‘object’. Why we say its depend also on observer, because there is no meaning of motion and rest without an observer .

Here we need an observer for measuring the movement of object. So after that a question arises , how can we observe the objects to know weather it is in motion or at rest !!

For this we need frame of reference. Now Lets discuss about what is frame of reference means.

Frame of reference…

Why is this, because the movement of body depends on the frame of observation.

It is a system of geometric axes in relation to which measurements of 𝙨𝙞𝙯𝙚, 𝙥𝙤𝙨𝙞𝙩𝙞𝙤𝙣, or 𝙢𝙤𝙩𝙞𝙤𝙣 be made for deciding the initial position of objects . It is important for describing the displacement of object.

In physics we generally take coordination system to define the position of object.

Lets take an example for understanding is in better way — suppose a book is place inside the car and car is moving with some velocity, and the book is observer from outside the car then we said that the book is in motion with respect to the ground, and now the book is observe from inside the car then it said that it is at rest.

Some terms comes under it…

𝘿𝙞𝙨𝙩𝙖𝙣𝙘𝙚 – supose a body is move a path A to B through C then the path ACB called the ‘distance’ covered by the particle in a given time frame.

Therefore, ”distance is the actual path cover by and object in a given interval of time”. It is a scalar quantity, SI Unit is 𝚖 ( meter), and dimension is [L].

𝘿𝙞𝙨𝙥𝙡𝙖𝙘𝙚𝙢𝙚𝙣𝙩 – taking the same path mentioned above if we join A and B through a straight line we get AB as displacement.

So, “It is the shortest distance/shortest path cover by an abject in given time interval”. It is a vector quantity because it has magnitude and direction both . Unit is 𝚖 , and dimension is [L].

𝙎𝙥𝙚𝙚𝙙– it is the distance covered by an object per unit time. It has only magnitude is a scalar quantity with SI unite 𝚖/s, written as — speed of a abject is 40 m/s .And has dimension [LT-¹].

★𝙰𝚟𝚊𝚛𝚊𝚐𝚎 𝚜𝚙𝚎𝚎𝚍– it the total distance cover in total time interval.

★𝙸𝚗𝚜𝚝𝚊𝚗𝚝𝚊𝚗𝚎𝚘𝚞𝚜 𝚜𝚙𝚎𝚎𝚍 – for this let the distance ‘s’ approaches zero and the time ‘t’ also approaches zero but the faction ‘s/t’ has some finite valve. Then it speed called instantaneous speed

𝙑𝙚𝙡𝙤𝙘𝙞𝙩𝙮– it is the displacement of object per unit time. It has magnitude as well as direction so it is a vector quantity, with SI unit 𝚖/𝚜 ,same as speed but can be written as — a body is moving with velocity ’30m/s toward east’. Also the dimensions are same as speed.

★𝙰𝚟𝚊𝚛𝚊𝚐𝚎 𝚟𝚎𝚕𝚘𝚌𝚒𝚝𝚢– this is the total displacement in total time interval.

★𝙸𝚗𝚜𝚝𝚊𝚗𝚝𝚊𝚗𝚎𝚘𝚞𝚜 𝚟𝚎𝚕𝚘𝚌𝚒𝚝𝚢 – let the time ‘t’ tents to zero and displacement also tents to zero but we have a faction ‘s/t’ with some valve.

𝘼𝙘𝙘𝙚𝙡𝙚𝙧𝙖𝙩𝙞𝙤𝙣– It is the change in velocity per unite time. Its SI unite is 𝚖/s². It is also a vector quantity and has dimension [LT-²].

★ 𝙰𝚟𝚊𝚛𝚊𝚐𝚎 𝚊𝚌𝚌𝚎𝚕𝚎𝚛𝚊𝚝𝚒𝚘𝚗 – it is the total change in velocity in total time interval.

★ 𝙸𝚗𝚜𝚝𝚊𝚗𝚝𝚊𝚗𝚎𝚘𝚞𝚜 𝚊𝚌𝚌𝚎𝚕𝚎𝚛𝚊𝚝𝚒𝚘𝚗– is the acceleration of an object in the fraction of a second .

𝙅𝙚𝙧𝙠– it is the rate at which an object changes it acceleration with respect to time. It is a vector quantity with unit 𝚖/s³ . And dimension is [LT-³].

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I Hope this is useful. Thanks for reading 😇.