It is believed that life on our planet Earth first originated around 3.6 billion years ago.
Since then many different types of organisms have evolved on the earth. We observe various types of living organisms like insects, birds worms, mammals and plants around us. Every organism in this world, whether, a plant, an animal or a microorganism is unique in itself. This uniqueness of individuals forms the basis of the diversity (or species richness) among the living organisms.
The term 'biodiversity’ (L. diversitas = variety) was coined by Walter G. Rosen in 1986.
Biodiversity can be defined as, the variability among living organisms from all sources including, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems.
For instance, compare yourself with your friend. Both of you have different looks, different figure, different heights and different qualities. But both are identified on the basis of certain characteristics. Now compare over selves and our friends with a monkey. The monkey is quite different from us that is because we and our friends have close similarities. The differentiation becomes sharp if we compare ourselves and monkey with a cow. Naturally we and monkey have more similarities in comparison to a cow. It can be concluded that each and every organism possess a distinct form that distinguishes it from others.
Various Ways of Expressing Biodiversity
Biodiversity can be expressed in the following ways:
(a) Genetic variability within a species: It includes the differences in body shape and size, colour etc. expressed due to genetic differences.
(b) Diversity of population of a species: This is expressed in terms of the number of individuals within a local group as well as the distribution of a species in geographical range.
(c) Diversity of species within a natural community: It includes the varieties of different species in a particular habitat.
(d) Ecosystem Diversity: The diversity at the level of community and ecosystem has four perspective.
(i) Point Diversity: This is a diversity on the smallest scale i.e., the diversity of micro- habitat.
(ii) Alpha Diversity: It includes the diversity of organisms sharing the same habitat and also called local diversity.
(iii) Beta Diversity: It refers to the rate of replacement of species along a gradient of habitats or community within a given geographical area.
(iv) Gamma Diversity: It refers to the diversity of the habitats in the whole geographical area.
Biodiversity of India
India has a great wealth of biodiversity in its more...
The branch of physics which deals with the study of motion of objects is called mechanics.
Statics is the study of object at rest and Dynamics is the study of object in motion.
The study of dynamics is further subdivided into:
(a) Kinematics
(b) Dynamics Proper.
Kinematics is the study of motion without taking into account the cause of motion.
Dynamics proper is the study of motion taking into account the cause of motion.
A body is said to be rest if it does not change its position with respect to its immediate surroundings.
On the other hand, a body is said to be in motion if it changes its position with respect to its immediate surroundings.
Example 1: When a tree T, is observed by m observer A sitting on a bench, the tree is at rest. This is because the position of the tree is not changing with respect to the observer A.
Now, when the same tree T is observed by an observe r B sitting in a superfast train moving with a velocity v, then the tree is moving with respect to the observer because the position of tree is changing with respect to the observer B.
2. Types of Motion
(1) Linear Motion: An object has linear motion if it moves in a straight line or path. It is also called rectilinear motion.
Examples of linear motion:
(i) Motion of a moving car on a straight road.
(ii) Motion of a ball dropped from the roof of a building.
(2) Circular (or Rotatory Motion): An object has circular motion if it moves around a fixed point.
The blades of a fan rotates around a fixed point and therefore have rotatory motion.
(3) Vibratory Motion: A body has vibratorynotion if it moves to and fro about a fixed point.
This type of motion called Vibratory Motion.
Example - The motion of a sitar string when plucked exhibits Vibratory Motion.
Scalar and Vector Quantities
Scalar Quantity The physical quantity which h ave only nagnitude an d no sense of direction is called scalar quantity
Examples: Mass, time, distance, more...
Variation of momentum when two bodies of equal/ different masses have different/ equal momenta
Second Law of Motion
Mathematical Formulation of Second Law of Motion
Newton’s First Law of Motion as a special case of Newton’s Second Law
Applications of Newton’s Third Law of Motion
Third Law of Motion
Examples to illustrate Newton’s Third Law of Motion
Conservation of Momentum
Introduction
"Gives us the knowledge of Laws of nature and both future and past will reveal their secrets".
-Issac Newton
In this chapter, we shall investigate the cause of motion and it will be found that a body at rest may be set into motion, when some force is applied on it.
The motion of the bodies can be understood by studying the relation between the force applied on a body and the effect produced by the applied force.
Do You Know
Force cannot be seen but the effect of force on an object can be seen or felt.
Force: It is a push or pull which either changes or tends to change the state of rest or of uniform motion of a body.
In our everyday life, we use force, quite frequently to perform various activities, some examples are kicking a football, squeezing a tube of toothpaste, lifting a book, catching a ball, opening a door etc.
Effects of Force
Force can:
(i) Move a body lying at rest:
(a) Kicking a stationary football.
(b) Lifting a book kept on a table top.
(c) Hitting a stationary ball with a bat.
(ii) Stop a moving body:
(a) A moving ball can be stopped by the force of our hand.
(b) A moving ball can stop on its own due to the force of friction.
(c) A rotating top can be stopped by the force exerted by our hands.
(iii) Change the speed of a moving body:
(a) If a person pushes a moving swing, if will move faster
(b) When more force is applied on the pedals by a cyclist, speed of cycle increases,
(iv) Change the direction of a moving body
(a) When a batsman hits the ball with his bat, the direction of the moving ball changes.
(b) A carom counter changes its direction after a collision.
(c) A football player hitting a ball coming towards him, towards the goal post.
(v) Change the shape and size of an object:
(a) When we squeeze a toothpaste tube, its gets flattened.
(b) When we stretch a rubber band, its shape more...
Gravitational Force between the Sun and the Planet
Universal Law of Gravitation or Newton’s Law of Gravitation
Important Characteristics of Gravitational Force
Importance of Universal Law of Gravitation
Definition of Acceleration due to Gravity
Relation between g and G
Variation of Acceleration due to Gravity (g)
Difference between G and g
Motion of Objects under the Influence of Gravitational Force of the Earth
Mass and Weight
Thrust and Pressure
Consequences of Pressure
Pressure in Fluids
Definition of Up thrust of Buoyant Force
Archimedes’ Principle
Applications of Archimedes’ Principle
Relative Density
Gravitation
According to Newton's first law of motion, planets and satellites can move in circular orbits only if some force is acting on them. Sir Issac Newton proposed that all particles or objects in the Universe attract each other in the same manner as the earth attracted the apple.
"The force of attraction between any two particles in the Universe is called Gravitation or gravitational force. Newton showed that gravitational force between two masses varies inversely proportional to the square of the distance between them. This fact was proved by him on the basis of Kepler's laws of planetary motion.
Kepler’s Laws regarding Motion of Planets
The German astronomer Johannes Kepler worked out on three empirical laws that govern the motion of the planets around the Sun.
(1) Kepler's First Law:
(i) Law of Orbits: Every planet revolves around the sun in an elliptical orbit with the Sun situated at one of the foci of the ellipse. Fig. 2.1.
P = Position of the planet
\[{{P}_{1}}\] = Position of the Sun.
(2) Kepler's Second Law:
(ii) Law of Areas: Each planet moves in such a way that an imaginary line drawn from the sun to the planet sweeps out equal area in equal interval of time.
According to Kepler's second law of motion if,
Time taken by the planet to move from \[{{P}_{1}}\]to\[{{P}_{2}}=Tim\]taken by the planet to move from\[{{P}_{3}}\]to\[{{P}_{4}}\]then
Area\[{{P}_{1}}S{{P}_{2}}=\]Area\[{{P}_{3}}S{{P}_{4}}\]
because the distance of the planet at position \[{{P}_{1}}\]is mor than the distance of the planet at position \[{{P}_{3}}\]from the sun, so \[{{P}_{1}}S>{{P}_{3}}S\] Fig .2.2.
\[\text{Speed=}\frac{\text{Distance}}{\text{Time}}\]or\[\text{Time}\frac{\text{Distance}}{\text{Speed}}\]
So, for equal time intervals speed along \[{{P}_{1}}{{P}_{2}}<\]Speed along \[{{P}_{3}}{{P}_{4}}\]
Conclusion: Velocity of a planet when closer to the sun is more than its velocity when away from the sun.
Law of Periods: According to more...
Comprehension
To comprehend means 'to understand and grasp'. Comprehension is an important segment that tests the ability fan individual to understand the language, his knowledge of vocabulary & grammar and how nicely can an examinee understand the given passage.
Trend of Tests
(i) Cloze Test
(ii) Reading Comprehension
(iii) Contextual Passage
(iv) Passage Completion and Error Detection
Cloze Test
A cloze test is an assessment of an examinee's comprehension abilities which includes a piece of text, from which a number of words has been removed. The student is required to insert missing words according to the context.
How to do the cloze test
·Read the passage carefully to get a general idea.
·Read again, this time a little slowly, to know the details.
·Identify the optional words to fill in the gaps.
·Pay special attention to the grammar around the words in each gap.
Example:
Direction: For Q. 1-4: Complete the passage by selecting the most suitable option from the list for the corresponding gap.
After an absence of thirty years, I decided to visit my old school again. I had___ (1) ____to find changes, but not a completely different building. As I walked up____ (2) ______school drive, I ___ (3) for a moment if I had come to the___ (4) ____address.
(a) known (b) expected
(c) hoped (d) imagined
(e) None of these
Answer: (b)
(a) our (b) my
(c) the (d) a
(e) None of these
Answer: (c)
(a) wondered (b) wonder
(c) wounded (d) wondering
(e) None of these
Answer (a)
(a) school (b) actual
(c) right (d) exact
(e) None of these
Answer (c)
Reading Comprehension
Reading comprehension implies understanding the meaning of a given article or a short passage. Comprehension tests are meant for testing the understanding level and capacity of the students. Students are required to read carefully and answer the questions. Students need to have a complete understanding of the passage before attempting to answer the questions.
Tips for answering
·Read the passage carefully to get the general idea.
·Understand the more...
Introduction
It is very important to develop a good store of vocabulary which gives one a niche in developing a rich sense of understanding and expressing In English language. This part includes:
(i) Word meaning
(ii) Synonyms and Antonyms
(iii) Phrases & ldioms
Word Meaning
We come across different words daily. Some words are simple as are normally used regularly, while a few are hard or difficult to understand. Words like, ruin, forecast, principle, etc. are common words. But certain words, like ingenious, adroit, infidel, agnostic, etc. are uncommon words and are difficult to understand. The usage of these words in sentences reduces the chance of easily understanding the text of meaning intended in the sentence.
A list of few uncommon words which are tough to understand
A
Abstain: keep oneself from doing or enjoying something; refrain.
Aloft: Up in the air; overhead.
Absurd: Unreasonable; not sensible; foolish in a funny way; ridiculous.
Authentic: Known to be true or genuine; trustworthy; reliable.
Abscond: Go away suddenly and secretly.
Amorous: Readily showing or feeling love
Affray: Disturbance of the peace caused by fighting or rioting in the public place.
Ardour: Great warmth of feeling; enthusiasm; zeal.
Use of Article
Articles are divided into two parts, that is, indefinite articles and definite article.
'A' and 'an' is regarded as indefinite article. ‘The' is the definite article.
Use of ‘A’
Apart from its usual uses before the words that start with a consonant sound, 'a' is also used;
With 'one'.
Example: a one-man show.
with vowel letters having consonant sound.
Example: a university.
With units and rate.
Example: Rice sells five rupees a kilo.
In exclamatory sentences before singular countable noun.
Example: What a pretty kid!
To make a common noun of a proper noun.
Example: This man is a second 'Einstein'.
Use of ‘An’
Apart from its use before the words that start with a vowel sound, 'an' is also used:
Before word beginning with silent 'h'.
Example: an hour
Before abbreviations beginning with F, H, L, M, N, R, S X, as they give a vowel sound.
Example: An F.I.R.
Use of 'The'
When we speak of a particular person,
Example: I love the guy.
When a singular noun represents a whole class.
Example: The guava is considered as the poor man's apple.
Religious groups.
Example: The Parsees
Names enforcing law.
Example: The police
Parts of Body; Musical Instruments; Political Parties etc.
With superlatives
Example: He is the best boy in the class of IX.
Before an adjective when the noun is understood.
Example: We must not shun the disabled.
Use of Noun
Some nouns are used in singular forms.
Motion
In the physical world, one of the most common phenomena is motion. The branch of Physics, which deals with the behavior of moving objects, is known as mechanics. Mechanics is further divided into two sections namely Kinematics and Dynamics.
Kinematics deals with the study of motion without taking into account the cause of motion.
Scalar Quantities: Physical quantities which have magnitude only and no direction are called scalar quantities.
Example: Mass, speed, volume, 'work, time, power, energy etc.
Vector Quantities: Physical quantities which have magnitude and direction both are called vector quantities.
Example: Displacement, velocity. Acceleration, Force, Momentum, torque etc.
Electric current though has a direction is a scalar quantity because it does not obey triangle law.
Distance: Distance is the length of actual path covered by a moving object in a given time interval.
Displacement: Shortest distance covered by a body in a definite direction is called displacement.
Distance is a scalar quantity whereas displacement is a vector quantity both having the same unit.
Displacement may be positive, negative or zero where distance is always positive,
Speed: Distance travelled by the moving object in unit time interval is called speed
Speed = Distance/Time. It is a scalar quantity and its SI unit is meter/second.
Velocity: Velocity of a moving object is defined as the displacement of the object in unit time interval i.e. velocity = Displacement/Time.
It is vector quantity and its SI unit is meter/second.
Acceleration: Acceleration of an object is defined is the rate of change of velocity of the object. Acceleration = Change in velocity/Time.
It is a vector quantity and its SI unit is meter/\[{{\operatorname{second}}^{2}}\].
Circular Motion: It an object describes a circular path its motion is called circular motion.
If the object moves with uniform speed its motion is uniform circular motion.
Uniform circular motion is an accelerated motion because the direction of velocity changes continuously.
Angular Motion: The angle subtended by the line joining the object from the origin of circle in unit time interval is called angular motion.
It is generally denoted by \[\omega \] and \[\omega ~=\theta /t\].
If T= time period = time taken by the object to complete one revolution,
n = frequency = no. of revolutions in one second.
nT = 1 and \[\omega =2\pi /T=2\pi n\].
In one revolution the object travels \[2\pi r\] distance.
Linear speed =\[\omega r=angular\text{ }speed\times radius\].
Newton’s Laws of Motion
Newton the father of physics established the laws of motion in his book ‘principia’ in 1667.
Newton's first laws of motion: Everybody maintains its initial state of rest or motion with uniform speed on a straight line unless an external force acts on it.
First law is also called law of Galileo or law of inertia.
Inertia: Inertia is the property of a body by virtue of which the body more...
Work, Energy and Power
Work
If a body gets displaced when a force acts on it, work is said to be done. Work is measured by the product of force and displacement of the body along the direction of force,
If a body gets displaced by S when a force F acts on it, then the work \[\operatorname{W}= F\,S cos\theta \]
Where \[\theta \] = angle between force and displacement.
If both force and displacement are in the same direction/ then W = FS.
Work is a scalar quantity and its SI unit is joule.
Energy
Capacity of doing work by a body is called its energy.
Energy is a scalar quantity and its SI unit is joule.
Energy developed in a body due to work done on it is called mechanical energy.
Mechanical energy is two types.
(i) Potential Energy
(ii) Kinetic Energy
Potential Energy: The capacity of doing work developed in a body due to its position or configuration is called its potential energy.
Example:
(i) energy of stretched or compressed spring
(ii) energy of water collected at a height
(iii) energy of spring in a watch.
E. of a body in the gravitational field of earth is mgh.
Where m = mass, g = acceleration due to gravity and h = height of the body from surface of the earth.
Kinetic Energy: Energy possess by a body due to its motion is called kinetic Energy of the body:
If a body of mass m is moving with speed v, then kinetic energy of the body K. E \[=\frac{1}{2}m{{v}^{2}}\]
Principle of Conservation of Energy
Energy can neither be created nor can be destroyed. Only energy can be transformed from one form to another from. Whenever energy is utilized in one form, equal amount of energy is produced in other form. Hence total energy of the universe always remains the same. This is called the principle of conservation of energy.
Sound
Sound is a wave caused by the movement of particles that travels through air or water similar to the ripples on a pond or the ocean waves you might see on a beach. A wave can be described as a disturbance that travels through a medium from one location to another location is called wave. There are two types of waves: Mechanical waves and electromagnetic waves.
Electromagnetic Waves
Electromagnetic waves are waves travelling through a vacuum and do not require a medium in order to transport their energy (propagation) e.g. Light.
Mechanical Waves
'Mechanical waves are waves which require a medium for propagation or to transport their energy from one point to another. It is of two types.
Longitudinal Wave: A mechanical waves in which the particles and the energy move in the same direction, parallel to the direction in which the wave is travelling.
A sound wave travelling through air is the example of longitudinal waves. Because particles of the medium through which the sound is transported, vibrate parallel to the direction to which the sound wave moves.
Compressions are the regions where particles are crowded together. The peak represents the region of maximum compression. Thus, compressions are regions where density as well as pressure is high.
Rarefactions are the regions of low pressure where particles are spread apart. The distance between two consecutive compressions (C) or two consecutive rarefactions (R) is called the wavelength. The wavelength is usually represented by A (Greek letter lambda). Its SI unit is meter (m).
Transverse wave: A wave in which particles of the medium move in a direction perpendicular to the direction to which the wave is travelling. The particles of medium vibrate up-and-down and the energy moves left-and-right. e.g. Water waves on the ocean surface.
A peak is called the crest and a valley is called the trough of a wave.
Propagation of Sound
The matter or substance through which sound is transmitted is called a medium. It can be solid/ liquid or gas.
We can describe a sound wave by its properties:
(a) Frequency (b) amplitude and (c) speed.
The number of such oscillations per unit time is the frequency of the sound wave. If we can count the number of the compressions or rarefactions that cross us per unit time, we will get the frequency of the sound wave. It is usually represented by n. lts SI unit is hertz (Hz).
The time taken for one oscillation is called time period. It is represented by the symbol T. Its SI unit is second (s).
Frequency and time period are related as follows: \[n=1/t\]
Pitch: How the brain interprets the frequency of an emitted sound is called the pitch. The faster the vibration of the source, the higher more...
The study of dynamics is further subdivided into:
(a) Kinematics
(b) Dynamics Proper.
Kinematics is the study of motion without taking into account the cause of motion.
Dynamics proper is the study of motion taking into account the cause of motion.
A body is said to be rest if it does not change its position with respect to its immediate surroundings.
On the other hand, a body is said to be in motion if it changes its position with respect to its immediate surroundings.
Example 1: When a tree T, is observed by m observer A sitting on a bench, the tree is at rest. This is because the position of the tree is not changing with respect to the observer A.
Now, when the same tree T is observed by an observe r B sitting in a superfast train moving with a velocity v, then the tree is moving with respect to the observer because the position of tree is changing with respect to the observer B.
2. Types of Motion
(1) Linear Motion: An object has linear motion if it moves in a straight line or path. It is also called rectilinear motion.
Examples of linear motion:
(i) Motion of a moving car on a straight road.
(ii) Motion of a ball dropped from the roof of a building.
(2) Circular (or Rotatory Motion): An object has circular motion if it moves around a fixed point.
The blades of a fan rotates around a fixed point and therefore have rotatory motion.
(3) Vibratory Motion: A body has vibratorynotion if it moves to and fro about a fixed point.
This type of motion called Vibratory Motion.
Example - The motion of a sitar string when plucked exhibits Vibratory Motion.
Fig. 2.1.
P = Position of the planet
\[{{P}_{1}}\] = Position of the Sun.
(2) Kepler's Second Law:
(ii) Law of Areas: Each planet moves in such a way that an imaginary line drawn from the sun to the planet sweeps out equal area in equal interval of time.
According to Kepler's second law of motion if,
Time taken by the planet to move from \[{{P}_{1}}\]to\[{{P}_{2}}=Tim\]taken by the planet to move from\[{{P}_{3}}\]to\[{{P}_{4}}\]then
Area\[{{P}_{1}}S{{P}_{2}}=\]Area\[{{P}_{3}}S{{P}_{4}}\]
because the distance of the planet at position \[{{P}_{1}}\]is mor than the distance of the planet at position \[{{P}_{3}}\]from the sun, so \[{{P}_{1}}S>{{P}_{3}}S\]
Fig .2.2.
\[\text{Speed=}\frac{\text{Distance}}{\text{Time}}\]or\[\text{Time}\frac{\text{Distance}}{\text{Speed}}\]
So, for equal time intervals speed along \[{{P}_{1}}{{P}_{2}}<\]Speed along \[{{P}_{3}}{{P}_{4}}\]
Conclusion: Velocity of a planet when closer to the sun is more than its velocity when away from the sun.
Law of Periods: According to more... 
It is generally denoted by \[\omega \] and \[\omega ~=\theta /t\].
If T= time period = time taken by the object to complete one revolution,
n = frequency = no. of revolutions in one second.
nT = 1 and \[\omega =2\pi /T=2\pi n\].
In one revolution the object travels \[2\pi r\] distance.
Linear speed =\[\omega r=angular\text{ }speed\times radius\].
Newton’s Laws of Motion
Newton the father of physics established the laws of motion in his book ‘principia’ in 1667.
Newton's first laws of motion: Everybody maintains its initial state of rest or motion with uniform speed on a straight line unless an external force acts on it.
First law is also called law of Galileo or law of inertia.
Inertia: Inertia is the property of a body by virtue of which the body
Compressions are the regions where particles are crowded together. The peak represents the region of maximum compression. Thus, compressions are regions where density as well as pressure is high.
Rarefactions are the regions of low pressure where particles are spread apart. The distance between two consecutive compressions (C) or two consecutive rarefactions (R) is called the wavelength. The wavelength is usually represented by A (Greek letter lambda). Its SI unit is meter (m).
Transverse wave: A wave in which particles of the medium move in a direction perpendicular to the direction to which the wave is travelling. The particles of medium vibrate up-and-down and the energy moves left-and-right. e.g. Water waves on the ocean surface.
A peak is called the crest and a valley is called the trough of a wave.
Propagation of Sound
The matter or substance through which sound is transmitted is called a medium. It can be solid/ liquid or gas.
We can describe a sound wave by its properties:
(a) Frequency (b) amplitude and (c) speed.
The number of such oscillations per unit time is the frequency of the sound wave. If we can count the number of the compressions or rarefactions that cross us per unit time, we will get the frequency of the sound wave. It is usually represented by n. lts SI unit is hertz (Hz).
The time taken for one oscillation is called time period. It is represented by the symbol T. Its SI unit is second (s).
Frequency and time period are related as follows: \[n=1/t\]
Pitch: How the brain interprets the frequency of an emitted sound is called the pitch. The faster the vibration of the source, the higher
