Free PDF Download of NCERT chapter-wise solutions for class 9 Science solved by expert teachers from latest edition books and as per NCERT (CBSE). Science. NCERT/CBSE class 9 Science book Science. Contain Page. NCERT/ CBSE class 9 Science book Science. CHAP 1. NCERT/CBSE class 9 Science. NCERT book for class 9 Science subject is available here. Students may read and download each chapter in PDF format. Follow the NCERT books to get a clear.
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Chapter 9. Force and Laws of Motion. Chapter Work and Energy. Why Do We Fall Ill. Natural Resources. Improvement in Food Resources. Class 9 Science NCERT book mainly focuses on explaining the fundamentals of the subject so as to help students grasp the basic concepts easily.
NCERT books are all-inclusive and accomplished in their own sense. These books are not only important to prepare for the board exams in classes 10 and 12 but also for other competitive exams. All NCERT books are written by experts after an extensive research on each and every topic to provide appropriate and authentic information to the students. Students must solve all the exercise questions given at the end of every chapter and then check their solutions to evaluate their performance.
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List of Oscar Award Winner. Daily Current Affairs. A ball on the ground, when given a small hit, does not move forever. This remained the belief until Galileo Galilee and Isaac Newton developed an entirely different approach to understand motion. In force, both magnitude and direction is considered.
Concept of balanced and unbalanced force is discussed. In balanced force, net force is zero, as equal magnitude of force is applied from opposite sides.
Net force is zero. In unbalanced force, net force is not equal to zero. For change of state from rest to motion, or motion to rest, or to change velocity of an object, unbalanced force is required. So, this much is the concept of force. First law of motion: An object continues to be in a state of rest or of uniform motion along a straight line unless acted upon by an unbalanced force. The natural tendency of objects to resist a change in their state of rest or of uniform motion is called inertia.
The first law is also known as law of inertia. The law has been explained with several examples. The mass of an object is a measure of its inertia. Its SI unit is kilogram kg. Force of friction always opposes motion of objects. Second law of motion says, The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force. The SI unit of force is kg m s —2. This is also known as newton and represented by the symbol N.
A force of one newton produces an acceleration of 1 ms —2 on an object of mass 1 kg. The momentum of an object is the product of its mass and velocity and has the same direction as that of the velocity. Its SI unit is kg ms —1 ,also known as Newton. Third law of motion says, To every action, there is an equal and opposite reaction and they act on two different bodies. In an isolated system where there is no external force , the total momentum remains conserved.
Gravitation In previous chapter it is discussed force is required for motion. We have learnt that a force is needed to change the speed or the direction of motion of an object. We always observe that an object dropped from a height falls towards the earth. We know that all the planets go around the Sun. The moon goes around the earth. In all these cases, there must be some force acting on the objects, the planets and on the moon.
Sir Isaac Newton figured out that force responsible for all these things is Gradational force. The gravitational force is force acting between two bodies due to their masses. The chapter starts with the concept of gravitation. After that Universal Law of Gravitation was discussed. The gravitational force acting between two bodies is directly proportional to the product of their masses and inversely proportional to the square of distance between them.
The gravitational force is responsible for motion of planets, free fall of any object, tides in oceans. Whenever objects fall towards the earth under this force alone, we say that the objects are in free fall. If two bodies are thrown from same height, irrespective of their masses both of them will fall together with same acceleration due to gravity g.
Equations of motions can be written accordingly. The concept of mass and weight is discussed. Mass of an object is the measure of its inertia. Weight is gravitational force acting on the body. For body of mass m, weight is mg, where g is acceleration due to gravity.
So, value of g will vary with that. Moon is having lesser mass and radius than earth. It is important to understand the difference between mass and weight. Thrust and Pressure are discussed after that. Thrust is vertical force acting on any object. The concept has been explained in chapter with suitable examples.
Thrust is also created by liquids kept on the base and walls of the container in which they are enclosed. Pressure exerted in any confined mass of fluid is transmitted undiminished in all directions. When an object is placed in the liquid, upward force is experienced on it. The force is Buoyant force. The magnitude of this buoyant force depends on the density of the fluid. Relative density is the ratio of density of that object with respect of density of water. If it is more than 1, the object will sink in water, otherwise it will float.
Work and Energy In previous chapter, we have discussed about force, motion and gravitation. We need energy for other activities like playing, singing, reading, writing, thinking, jumping, cycling and running.
Activities that are strenuous require more energy. Work and energy are related. Both are explained one by one. First, the concept of work is to be understood. Definition of work done is different from day to day life. Work is defined for a force. Work is defined as force multiplied by displacement. If there is no displacement, we say there is no work. The concept is dealt here. SI unit of work done is joule. It is important, in displacement direction is considered.
If the force and displacement are in same direction the work done is positive.
If force and work done are perpendicular to each other, work done is zero. If displacement is made in opposite direction of force applied, the work done is in opposite direction. Energy is defined as capacity to do the work. The Sun is the biggest natural source of energy to us.
How does an object with energy do work? An object that possesses energy can exert a force on another object. When this happens, energy is transferred from the former to the latter. The second object may move as it receives energy and therefore do some work. The unit of energy is, therefore, the same as that of work, that is, joule J. Forms of Energy are discussed after that. Kinetic energy is energy possessed by a body in motion. Kinetic energy of a body moving with a certain velocity is equal to the work done on it to make it acquire that velocity.
Potential energy is defined as energy stored in an object. For example, when an spring is contracted or expanded, some energy is stored in it. The spring comes back to its original position when left using energy stored in it.
Similarly, if some object is kept at some height, gravitational potential energy is stored in it. We can say, the potential energy possessed by the object is the energy present in it by virtue of its position or configuration. Energy is conserved. If an object is kept at height it gains potential energy, when dropped its potential energy started converting into kinetic energy. At any point of time during free fall, the net energy is same.
That is some of potential energy and kinetic energy will remain always same. This is law of conservation of energy. Rate of doing work is known as Power.
The SI unit of power is watt. The energy used in one hour at the rate of 1kW is called 1 kW h. It is also known as commercial unit of energy. Sound Sound is a form of energy which produces a sensation of hearing in our ears. Different types of sound we hear in our day to day to life.
These are the sounds of bird, horn of cars, children crying around and many more. There are also other forms of energy like mechanical energy, light energy etc. We know that energy is conserved and can change its form. When we clap, the mechanical energy is converted into sound energy.
Sound is produced due to vibration of different objects. Sound travels as a longitudinal wave through a material medium. Sound travels as successive compressions and rarefactions in the medium. In sound propagation, it is the energy of the sound that travels and not the particles of the medium. Sound cannot travel in vacuum. The change in density from one maximum value to the minimum value and again to the maximum value makes one complete oscillation. The time taken by the wave for one complete oscillation of the density or pressure of the medium is called the time period, T.
The number of complete oscillations per unit time is called the frequency. The speed of sound depends primarily on the nature and the temperature of the transmitting medium.
The law of reflection of sound states that the directions in which the sound is incident and reflected make equal angles with the normal to the reflecting surface at the point of incidence and the three lie in the same plane. For hearing a distinct sound, the time interval between the original sound and the reflected one must be at least 0. The persistence of sound in an auditorium is the result of repeated reflections of sound and is called reverberation.
Sound properties such as pitch, loudness and quality are determined by the corresponding wave properties. Loudness is a physiological response of the ear to the intensity of sound. The amount of sound energy passing each second through unit area is called the intensity of sound. The audible range of hearing for average human beings is in the frequency range of 20 Hz — 20 kHz. Ultrasound has many medical and industrial applications. The SONAR technique is used to determine the depth of the sea and to locate under water hills, valleys, submarines, icebergs, sunken ships etc.
Why do we Fall Ill? Health and disease in human communities are very complex issues. In our organs or tissues, there are various specialised activities going on — the heart is beating, the lungs are breathing, the kidney is filtering urine, the brain is thinking. All these activities are interconnected. For healthy well-being, it is very important every organ of human beings should work properly. In this chapter the term health is defined and explained.
Topics in this chapter will revolve around topics like give a brief idea about pure substances, solutions, mixtures, suspensions and colloidal. This will help a student to revise and reconnect efficiently. The chapter 3 of class 9 Science, Atoms and Molecules, depicts about the ideas of divisibility of matter. As one goes further through the chapter 3, Atoms and Molecules, an important topic called what is a molecule? You will learn how to write chemical formula of simple compounds, molecular mass and mole concepts, formula unit mass.
Charged Particles in any matter topic in this chapter conveys the concept that an atom is divisible and contains charged particles. The chapter 5, fundamental unit of life is in continuation with what the students have learnt in lower grades related to the levels of organization.
In this chapter, students will get a good grip over the topics such as the Plant Tissues such as meristematic tissue and permanent tissue. Also, some important concepts including location of meristematic tissues in plant body, various types of simple tissues, section of a stem, guard cells, etc will be learned. This chapter explains the importance of relevant groups to study the importance of various life forms. In this chapter, you will learn about the broad groups of organisms.
In living organisms diversity, there are attempts made by the famous scientist, Aristotle — and Classification of animals had been done according to their living on land, water or air. Classification of organisms which you will learn in this chapter is as follows - Kingdom, Phylum, Class, Order, Family, Genus, Species and Nomenclature. In Chapter 8, Motion, you will learn about motion including motion along a straight line , types of motion like uniform motion and non-uniform motion.
Acceleration — Rate of change of velocity and average speed and velocity. Graphical representation of motion, derivation of three equation of motion and numerical based on equation of motion. Concepts on uniform circular motion. In this chapter, you will learn the concept of balance and unbalance forces. You will then learn the idea behind the Second law of motion — momentum, rate of change of momentum. And gradually, the Third law of motion — for every action there is equal and opposite reaction, applications on first, second and third laws of motion.
In Chapters 8 and 9, you must have learnt about the motion of various objects and force as the cause of that motion. Thus, you might also be aware that force is needed to change the speed or the direction of motion of any object. Application of kinetic and potential energy, energy of an object at a certain height. This chapter is a very interesting one as you will get to learn about the Reflection of Sound ECHO, reverberation, and applications of multiple reflections of sound.
All these concepts are taught with by implementing various activities needed to be done in the Physics laboratory that makes the learning process more effective and interactive. In this chapter, you will understand the details of health and diseases. Health and its significance, reasons about why we fall ill and much more. Important topics like distinctions between healthy and disease free person and Personal and community issues for health are included.
The chapter take you through the importance of the Breath of Life: This topic is subdivided into topics such as the role of the atmosphere in climate control, how air moves movement of air: This chapter explains you about Improvement in Crop Yields and other useful topics.
How to make Improvement in food resources and livestock? The major groups of activities for improving crop yields —Crop production improvement, crop variety improvement, crop protection management.
Studying for long hours trying to decode the solutions to intricate problems can make you end up in a frustrating situation. This way you will be clear of what topic to concentrate more and how much time to spend on a particular topic or question. Not to mention, all the solutions are prepared by Science expert teachers of Vedantu that give you an in-depth understanding of each and every topic of Class 9 Science NCERT textbook questions. For all those students who often require additional guidance whenever they feel they are stuck — No need to worry as Vedantu has got your back.
Vedantu offers Online Classes to improve your chances of a higher score in the exams. You are always welcome to ask your doubts by taking online tuitions from Vedantu. This is highly beneficial for problems where the steps involved constitute elements that a student is usually unfamiliar with.
In these situations, you can end up spending a lot of useless time trying to understand very simple concepts. The Vedantu faculty can help you clarify any doubts that may grow in your minds eventually. The intense pressure of CBSE Class 9 final exams can have a negative impact on you and the right coaching can help negate that thing from your mind. Chapter 1: Matter in Our Surroundings The chapter completely depicts the importance of matter based on their physical properties and chemical nature.
Chapter 2: Chapter 3: Atoms and Molecules The chapter 3 of class 9 Science, Atoms and Molecules, depicts about the ideas of divisibility of matter.