# NCERT Class 9 Science Motion

Read and download NCERT Class 9 Science Motion in NCERT book for Class 9 Science. You can download latest NCERT eBooks chapter wise in PDF format free from Studiestoday.com. This Science textbook for Class 9 is designed by NCERT and is very useful for students. Please also refer to the NCERT solutions for Class 9 Science to understand the answers of the exercise questions given at the end of this chapter

## NCERT Book for Class 9 Science Chapter 8 Motion

Class 9 Science students should refer to the following NCERT Book Chapter 8 Motion in Class 9. This NCERT Book for Class 9 Science will be very useful for exams and help you to score good marks

### Chapter 8 Motion NCERT Book Class 9

MOTION

In everyday life, we see some objects at rest and others in motion. Birds fly, fish swim, blood flows through veins and arteries and cars move. Atoms, molecules, planets, stars and galaxies are all in motion. We often perceive an object to be in motion when its position changes with time. However, there are situations where the motion is inferred through indirect evidences. For example, we infer the motion of air by observing the movement of dust and the movement of leaves and branches of trees. What causes the phenomena of sunrise, sunset and changing of seasons? Is it due to the motion of the earth? If it is true, why don’t we directly perceive the motion of the earth?

An object may appear to be moving for one person and stationary for some other. For the passengers in a moving bus, the roadside trees appear to be moving backwards. A person standing on the road–side perceives the bus alongwith the passengers as moving. However, a passenger inside the bus sees his fellow passengers to be at rest. What do these observations indicate?

Most motions are complex. Some objects may move in a straight line, others may take a circular path. Some may rotate and a few others may vibrate. There may be situations involving a combination of these. In this chapter, we shall first learn to describe the motion of objects along a straight line. We shall also learn to express such motions through simple equations and graphs. Later, we shall discuss ways of describing circular motion.

8.1 Describing Motion

We describe the location of an object by specifying a reference point. Let us understand this by an example. Let us assume that a school in a village is 2 km north of the railway station. We have specified the position of the school with respect to the railway station. In this example, the railway station is the reference point. We could have also chosen other reference points according to our convenience. Therefore, to describe the position of an object we need to specify a reference point called the origin.

8.1.1 MOTION ALONG A STRAIGHT LINE

The simplest type of motion is the motion along a straight line. We shall first learn to describe this by an example. Consider the motion of an object moving along a straight path. The object starts its journey from  which is treated as its reference point (Fig. 8.1). Let A, B and C represent the position of the object at different instants. At first, the object moves through C and B and reaches A. Then it moves back along the same path and reaches C through B.

The total path length covered by the object is OA + AC, that is 60 km + 35 km = 95 km. This is the distance covered by the object. To describe distance we need to specify only the numerical value and not the direction of motion. There are certain quantities which are described by specifying only their numerical values. The numerical value of a physical quantity is its magnitude. From this example, can you find out the distance of the final position C of the object from the initial position O? This difference will give you the numerical value of the displacement of the object from O to C through A. The shortest distance measured from the initial to the final position of an object is known as the displacement.

Can the magnitude of the displacement be equal to the distance travelled by an object? Consider the example given in (Fig. 8.1). For motion of the object from O to A, the distance covered is 60 km and the magnitude of displacement is also 60 km. During its motion from O to A and back to B, the distance covered = 60 km + 25 km = 85 km while the magnitude of displacement = 35 km. Thus, the magnitude of displacement (35 km) is not equal to the path length (85 km).

Further, we will notice that the magnitude of the displacement for a course of motion may be zero but the corresponding distance covered is not zero. If we consider the object to travel back to O, the final position concides with the initial position, and therefore, the displacement is zero. However, the distance covered in this journey is OA + AO = 60 km + 60 km = 120 km. Thus, two different physical quantities — the distance and displacement, are used to describe the overall motion of an object and to locate its final position with reference to its initial position at a given time.

Please refer to attached file for NCERT Class 9 Science Motion

 NCERT Class 9 Science Matter In Our Surroundings NCERT Class 9 Science Matter In Our Surroundings Questions
 NCERT Class 9 Science Is Matter Around Us Pure NCERT Class 9 Science Is Matter Around Us Pure Questions
 NCERT Class 9 Science Atoms And Molecules NCERT Class 9 Science Atoms And Molecules Questions
 NCERT Class 9 Science Structure Of The Atom NCERT Class 9 Science Structure Of The Atom Questions
 NCERT Class 9 Science The Fundamental Unit Of Life NCERT Class 9 Science The Fundamental Unit Of Life Questions
 NCERT Class 9 Science Tissues NCERT Class 9 Science Tissues Questions
 NCERT Class 9 Science Diversity In Living Organisms NCERT Class 9 Science Diversity In Living Organisms Questions
 NCERT Class 9 Science Motion NCERT Class 9 Science Motion Questions
 NCERT Class 9 Science Force And Laws Of Motion NCERT Class 9 Science Force And Laws Of Motion Questions
 NCERT Class 9 Science Gravitation NCERT Class 9 Science Gravitation Questions
 NCERT Class 9 Science Work And Energy NCERT Class 9 Science Work And Energy Questions
 NCERT Class 9 Science Sound NCERT Class 9 Science Sound Questions
 NCERT Class 9 Science Why Do We Fall Ill NCERT Class 9 Science Why Do We Fall Ill Questions
 NCERT Class 9 Science Natural Resources NCERT Class 9 Science Natural Resources Questions
 NCERT Class 9 Science Improvement In Food Resources NCERT Class 9 Science Improvement In Food Resources Questions
 NCERT Class 9 Science Solutions and Answers

### Science NCERT Book Class 9 Chapter 8 Motion

The above NCERT Books for Class 9 Science Chapter 8 Motion have been published by NCERT for latest academic session. The textbook by NCERT for Chapter 8 Motion Science Class 9 is being used by various schools and almost all education boards in India. Teachers have always recommended students to refer to Chapter 8 Motion NCERT etextbooks as the exams for Class 9 Science are always asked as per the syllabus defined in these ebooks. These Class 9 Chapter 8 Motion book for Science also includes collection of question. We have also provided NCERT solutions for Class 9 Science which have been developed by teachers of StudiesToday.com after thorough review of the latest book and based on pattern of questions in upcoming exams for Class 9 students.

### NCERT Book Class 9 Science Chapter 8 Motion

The latest NCERT book for Chapter 8 Motion pdf have been published by NCERT based on the latest research done for each topic which has to be taught to students in all classes. The books for Class 9 Science Chapter 8 Motion are designed to enhance the overall understanding of students. All Class 9 NCERT textbooks have been written in an easy to understand language which will help to enhance the overall level of Class 9 students.

#### Chapter 8 Motion NCERT Book Class 9 Science

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#### Class 9 Science Chapter 8 Motion NCERT Book

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#### Class 9 Chapter 8 Motion NCERT Book Science

For Class 9 Chapter 8 Motion we have provided books for students who have opted for Hindi and Urdu medium too. You can click on the links provided above to download all Hindi medium Class 9 Science Chapter 8 Motion book in easy to read pdf format. These books will help Class 9 Science students to understand all topics and also strictly follow latest syllabus for their studies. If you are looking to download the pdf version of Class 9 Science Chapter 8 Motion textbook issued by NCERT then you have come to the correct website

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