In this chapter we all are going to learn very important part of physics i.e. motion. Your mother has often told you to go in market and bring some goods. In a garden you may have seen kids enjoying swinging, see-saw and many more games. Tik tik sound of clock is very familiar to everyone. Travelling in train is one of the most joyous thing for children’s as we can get different food items which are available for sell in train, isn’t it? While walking on a road we see many vehicles passing you, out of them some goes faster and some are really slow also.
All above discussion is related to the most important branch of physics, known as mechanics. When we study about an object in motion then it is known as mechanics. Object can appear in two state viz. 1. State of rest, 2. State of motion.
Motion
Suppose that you and friends are playing cricket on ground. You have marked two positions on ground i.e. position of stumps. While taking run Harsh runs towards wicket keeper and Gaurav moves bowlers end. Now here you can say that the position of Harsh and Gaurav has been changed on the ground. So you have observed that the positions of your friends is changed with respect to surrounding (here it is ground). This is called as motion. So here the definition of motion in simple form: The change in position of object with respect to surrounding is called as motion.
To describe motion, we need to discuss following important parameters viz. Distance, time, speed etc. It is very convenient to compare motion of any two objects by observing the distance covered by them in certain fix interval of time. Clearly here you can conclude that the object covers certain distance in less time is moving faster than that of object covers the same distance in more time i.e. motion is completely time dependant quantity.
Motion may be uniform or non uniform depends upon the path covered and time taken. Uniform motion is one in which object travels equal distances in equal time intervals. Eg. Soldiers performing march pass, repeats every step off equal distance in equal time gap.
Non uniform motion is one in which object covers equal distances in unequal distances of time. Eg. Students participated in 200 m running doesn’t completes the race in same time.
Types of Motion
Now look at the following examples
- Parade of NCC or march pass on occasion of independence day.
- Children enjoying in merry-go-round.
- Motion of minute hand of clock, blades of ceiling fan.
- Motion of earth around itself as well as around sun.
- Buttery fly moving in the garden.
All of above examples are related to different types of motion. Motion is basically of following types
1. Linear/translational motion:-In this type the object travels from one place to another in straight path only. In this type of motion the initial position and final position of object may or may not be same. e.g. car moving on a straight road.
2. Rotational motion: –In this type the object travels around a fix point or fix object tracing the same path during entire motion. e.g. motion of moon around earth, satellite revolves around earth, planets moves around sun, electrons rotates around nucleus, children enjoying giant wheel in a fair, all of these are examples of rotational motion.
3. Oscillatory/periodic motion: –In thisof motion object traces same path again and again during motion. You must have enjoyed the swing in garden, there your body is following same path again and again. If you have seen a tailor stitching cloths on sewing machine, then observe the motion on needle of sewing machine, which also traces the same path within two fix positions is also a best example of oscillatory motion.
4. Random motion: – The motion of body which do not have specific path or pattern then the motion is termed as random motion. Just try to catch the mosquitoes in bed room, are they moves along fix path? Obviously not! They changes their path continuously in the motion, hence their motion cannot be specified using the same parameters used to discuss motions as mentioned in points 1,2,3.
Q. What do you mean by motion?
Ans: The change in position of object with respect to surrounding is called as motion.
Q. Which are the important parameter required to describe the motion.
Ans: Distance, time, speed etc
Q. State the types of motion
Ans: Linear/translational motion, Rotational motion, Oscillatory/periodic motion etc.