PSEB 9th Class Science Solutions Chapter 10 Gravitation

Punjab State Board PSEB 9th Class Science Book Solutions Chapter 10 Gravitation Textbook Exercise Questions and Answers.

PSEB Solutions for Class 9 Science Chapter 10 Gravitation

PSEB 9th Class Science Guide Gravitation Textbook Questions and Answers

Question 1.
How does the force of gravitation between two objects change when the distance between them is reduced to half?
Answer:
Let m1 and m2 be the masses of the two objects A and B respectively and ‘r’ be the distance between their centres. Therefore, according to the law of Gravitation, the force of attraction between them is given ahead:
PSEB 9th Class Science Solutions Chapter 10 Gravitation 1
Therefore, force of attraction will become four times when the distance between the two objects is reduced to half.

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 2.
Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
Solution:
Suppose F is the gravitational force that acts on an object of mass’m’.
∴ F = G. \(\frac{\mathrm{M} m}{r^{2}}\) …………….. (i)
and F = mg ………………….. (ii)
From (i) and (ii)
F = \(\frac{\mathrm{GM} m}{r^{2}}\) = mg
It is clear that F ∝ m but acceleration due to gravity ‘g’ does not depend upon mass ‘m’. Hence all objects (light or heavy) fall with the same speed when there is no air resistance.

Question 3.
What is magnitude of gravitational force between the earth and a 1 kg object on its surface? Take mass of earth to be 6 × 1024 kg and radius of the earth is 6.4 × 106 m. G = 6.67 × 10-11 Nm2 kg-2.
Solution:
Here, mass of the object (m) = 1 kg
Mass of the earth (M) = 6 × 1024 kg
Radius of the earth (R) = 6.4 × 106 m
The magnitude of force of gravitation between object of mass 1 kg and the earth
PSEB 9th Class Science Solutions Chapter 10 Gravitation 2

Question 4.
The earth and the moon are attracted to each other by gravitational force. Does the earth attracts the moon with a force that is greater than or smaller than or the same as the force with which the moon attracts the earth? Why?
Answer:
The earth attracts the moon with the same force as the force with which the moon attracts the earth. According to Newton’s third law., these two forces are equal and opposite.

Question 5.
If the moon attracts the earth, why does the earth not move towards the moon?
Answer:
According to Newton’s third law, the moon also attracts earth with a force equal to that with which the earth attracts the moon. But the earth is much larger than the moon. So, the acceleration produced in the earth (a ∝ 1/m) is very less and is not noticeable.

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 6.
What happens to the force between two objects, if

  1. the mass of one object is doubled?
  2. the distance between the objects is doubled and tripled?
  3. the masses of both objects are doubled?

Answer:
PSEB 9th Class Science Solutions Chapter 10 Gravitation 3
PSEB 9th Class Science Solutions Chapter 10 Gravitation 4
i.e. the force becomes four times the original force.

Question 7.
What is the importance of universal law of gravitation?
Answer:
Importance of universal law of gravitation:

  1. The gravitational force between the sun and the earth makes the earth move around the sun with a uniform speed.
  2. The gravitational force between the earth and the moon makes the moon move around the earth with uniform speed.
  3. The high and low tides are formed in sea due to the gravitational pull exerted by the sun and the moon on the surface of water.
  4. It is the gravitational pull of the earth, which holds our atmosphere in place.
  5. The gravitational pull of earth keeps us and other bodies firmly on the ground.

Question 8.
What is the acceleration of free fall?
Answer:
It is the acceleration produced when a body falls under the influence of the force of gravitation of the earth alone. Near the surface of the earth, its value is 9.8 m s-2.

Question 9.
What do we call the gravitational force between the earth and an object?
Answer:
The gravitational force between the earth and an object is called weight of the object.

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 10.
A person ‘A’ buys few grams of gold at poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought? If not, why?
[Hint: The value of g is greater at the poles than at the equator.]
PSEB 9th Class Science Solutions Chapter 10 Gravitation 5
Answer:
The value of g at the equator is less than that at the poles. Hence, the few gm of gold at poles will measure less when taken to the equator. Therefore, the friend will not agree with the weight of the gold bought.

Question 11.
Why will a sheet of paper fall slower than one
Answer:
The sheet of paper will experience a larger air resistance due to its large surface area than that of its ball form.
PSEB 9th Class Science Solutions Chapter 10 Gravitation 6
Increased force of friction will reduce the forward driving force due to gravity. Hence sheet of paper falls slower than one that is crumbled into a ball.

Question 12.
Gravitational force on the surface of moon is 1/6th as strong as gravitational force on the earth. What is the weight in newton of a 10 kg object on moon and on the earth?
Solution:
Mass of the object on moon = 10 kg
Mass of the object on the earth = 10 kg
Acceleration due to gravity on the earth (g) = 9.8 m s-2
Weight of the object on the earth (W) = m × g
= 10 × 9.8
= 98 N
Now weight of the object on moon’s surface = \(\frac {1}{6}\) × weight of the object on earth
= \(\frac {1}{6}\) × 98N
= 16.3 N

Question 13.
A ball is thrown vertically upwards with a velocity of 49 m s-1. Calculate :
1. The maximum height to which it rises
2. The total time it takes to return to the surface of earth.
Solution:
1. Here initial velocity of the ball (u) = 49 m s-1
[At maximum height the ball comes to rest]
Final velocity of the ball (υ) = 0
Acceleration due to gravity (g) = – 9.8 m s2 [in the upward direction]
Time to reach the maximum height (t) =?
PSEB 9th Class Science Solutions Chapter 10 Gravitation 7
∴ Total time taken to return to earth = Time for upward journey + Time for downward journey
= t + t
= 2 t
= 2 × t
= 2 × 5 s
= 10 s

Question 14.
A stone is released from the top of a tower of height 19.6 m. Calculate the final velocity just before touching the ground.
Solution:
Here, the height of the tower, (h) = 19.6 m
Initial velocity of stone, (u) = 0
Acceleration due to gravity, (g) = + 9.8 m s-1
Final velocity of the stone, (υ) = ?
Using equation of motion, υ2 – u2 = 2gh
υ2 – (0)2 = 2 × 9.8 × 19.6
υ2 = 19.6 × 19.6
υ = \( \sqrt{{19.6 × 19.6}} \)
or υ = 19.6 ms-1

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 15.
A stone is thrown vertically upward with an initial velocity of 40 m s-1. Taking g = 10 m s-2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
Solution:
Initial velocity of the stone, (w) = 40 ms-1,
Final velocity of the stone on reaching maximum height (υ) = 0 [At rest]
Acceleration due to gravity, (g) = – 10 m s2 [upward direction]
Maximum height reached, (h) = ?
We know υ2 – u2 = 2gh
(0)2 – (40)2 = 2 × (- 10) × h
– 40 × 40 = – 2 × 10 × h
∴ h = \(\frac {-40×40}{-2×10}\)
= 80 m
Since stone goes 80 m upwards and then returns to the point of throw by moving 80 m downward.
∴ Total distance travelled by stone = h + h
= 2 h
= 2 × 80 m
= 160 m
As the stone returns to the initial point of throw, therefore, net displacement is zero (0)

Question 16.
Calculate the force of gravitation between the earth and the sun, given the mass of earth = 6 × 1024 kg and of the sun = 2 × 1030 kg. Average distance between the two is 1.5 × 1011 m.
Solution:
Given, mass of the earth (m1) = 6 × 1024 kg
Mass of the sun, (m2) = 2 × 1030 kg
Average distance between the earth and the sun (d) = 1.5 × 10-11 m
G = 6.7 × 10-11 N – m2 /kg2
Force of gravitation (F) = ?
According to the universal law of gravitation,
PSEB 9th Class Science Solutions Chapter 10 Gravitation 8

Question 17.
A stone is allowed to fall from the top of the tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m s-1. Calculate when and where the two stones will meet? (g = 10 ms-2)
Solution:
PSEB 9th Class Science Solutions Chapter 10 Gravitation 9
Height of the tower = 100 m
Suppose a stone is allowed to fall from point A at the top of tower and another stone is projected vertically upward from point C. Let us suppose that these two stones meet at point B after ‘t’ seconds.
Distance covered by first stone (AB) = x
∴ Distance covered by second stone (CB) = (100 – x)
Downward Journey of first stone
u = 0
g = + 10 m s-2
(S) = x metres
using S = ut + \(\frac {1}{2}\)gt2
x = 0 × t + \(\frac {1}{2}\) × 10 × t2
x = 0 + 5 × t2
⇒ t2 = \(\frac {x}{5}\) …………..(1)
Upward journey of second stone
u = 25 ms-1
(S) = (100 – x) metres
g = – 10 m s-2
using S = ut + \(\frac {1}{2}\)gt2
(100 – x) = 25 × t + \(\frac {1}{2}\)(-10) × t2
(100 – x) = 25t – 5t2
or 5t2 = 25t – 100 + x
From (1) and (2)
\(\frac {x}{5}\) = \(\frac {25t-100+x}{5}\)
or x = 25t – 100 + x
0 = 25t – 100
25t = 100
∴ t = \(\frac {100}{25}\) = 4s
Now substituting the value of t = 4s in (1)
(4)2 = \(\frac {x}{5}\)
16 = \(\frac {x}{5}\)
∴ x = 16 × 5 = 80 m
i.e. the first stone will cover a distance of 80 m in the downward direction, and second stone will cover upward distance = 100 – x
= 100 – 80
= 20 m

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 18.
A ball thrown up vertically returns to the thrower after 6 s. Find

  1. Velocity with which it was thrown up,
  2. the maximum height it reached; and
  3. its position after 4 s.

Solution:
Total time taken (t) = 6 s
Time taken by the ball for upward joumey= Time taken by the ball for downward journey
= \(\frac {6s}{2}\)
= 3 s
(i) Suppose the ball is thrown upwards with initial velocity u
g = – 9.8 m/s2
t = 3 s
υ = 0 [the ball stops on reaching the maximum height]
Maximum height(S) = h
using υ = u + gt
0 = u + (-9.8) × 3
0 = u – 29.4
∴ u = 29.4 ms-1

PSEB 9th Class Science Solutions Chapter 10 Gravitation 10
∴ Height of the ball from the thrower = (44.1 – 4.9) m
= 39.2 m

Question 19.
In what direction does the buoyant force on an object immersed in a liquid act.
Answer:
If an object is immersed in a liquid then the buoyant force due to displaced liquid acts on the object in vertically upward direction.

Question 20.
Why does a block of plastic immersed under water come to the surface of water?
Or
Give reason why, a block of plastic when immersed underwater comes up to the surface of water.
Answer:
As density of plastic is less than the density of water. The upward thrust applied by displaced water on the plastic will be more than the weight of the plastic. So plastic block will float on water.

Question 21.
The volume of 50 g of a substance is 20 cm3. If the density of water is 1 g cm-3, will the substance float or sink?
Solution:
Here, density of water, pw = 1gm cm-3
Mass of substance, m = 50g
Volume of substance, V = 20cm3
We know, density of substance, ρ = \(\frac {m}{v}\)
= \(\frac{500 \mathrm{~g}}{350 \mathrm{~cm}^{3}}\)
= 2.5 g cm-3
As the density of the substance is greater than the density of water, the given substance will sink in water.

Question 22.
The volume of 500 g sealed packet is 350 cm3. Will the packet float or sink in water if the density of water is 1 g cm-3 ? What will be the mass of the water displaced by this packet?
Solution:
Here, mass of the packet (m) = 500 g
Volume of packet (V) = 350 cm3
∴ Density of sealed packet ρ = \(\frac {m}{v}\)
= \(\frac{500 \mathrm{~g}}{350 \mathrm{~cm}^{3}}\)
= 1.43 gcm-3
But Density of water ρw = 1 g cm-3
As density of sealed packet is more than that of water, the sealed packet will sink in water.
∴ Volume of sealed packet immersed in water = V = 350 cm3
Weight of water displaced by the packet = Vρw
= 350 × 1
= 350g.

Science Guide for Class 9 PSEB Gravitation InText Questions and Answers

Question 1.
State the universal law of gravitation.
Answer:
Newton’s universal law of gravitation. This law states that every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. This force always acts along the line joining their centres.

If m1 and m2 are the masses of two objects lying distance d apart, then force F between them is:
F = \(\frac{\mathrm{Gm}_{1} m_{2}}{d^{2}}\)
where G is a constant, called universal gravitational constant.

Question 2.
Write the formula to find the magnitude of gravitational force between the earth and an object on the surface of the earth.
Answer:
PSEB 9th Class Science Solutions Chapter 10 Gravitation 11
Let ‘m’ be the mass of object on the earth and the mass of earth be ‘M’. If ‘R’ is the radius of the earth, then the formula for gravitational force between earth and object is:
F = \(\frac{\mathrm{Gm} M}{R^{2}}\)
Since the size of the object is very small as compared to that of the earth, therefore distance between centre of object and centre of the earth is taken to be equal to radius of the earth.

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 3.
What is meant by Free Fall?
Answer:
Free Fall: An object is said to be in a state of free fall when it falls towards the earth under the influence of gravitational force between the object and the earth. There is no change in the direction of motion of the body but value of velocity keeps changing due to attraction of earth.
It falls towards earth with an acceleration of 9.8 m s-2.

Question 4.
What is meant by acceleration due to gravity?
Answer:
Acceleration due to gravity: The acceleration produced in the motion of a body falling under the force of gravity is called acceleration due to gravity. It is denoted by ‘g’.

Question 5.
What is the difference between the mass of an object and its weight?
Answer:
Difference between mass and weight:

Mass Weight
1. Mass is the quantity of matter contained in a body and is the measure of its inertia. Weight of a body is the force with which a body is attracted towards the centre of the earth.
2. Mass of a body remains constant at all places. Weight of a body (W = mg) changes from place to place due to the change in the value of acceleration due to gravity ‘g’.
3. Mass is a scalar quantity. Weight is a vector quantity.
4. Mass is measured by a pan balance. Weight of a body is measured by a spring balance.
5. Mass of a body is never zero. Weight of a body is zero at the centre of the earth.
6. The unit of mass is kg. The unit of weight is newton or kg-wt.

Question 6.
Why is the weight of the object on moon -th of its weight on the earth?
Answer:
We know that, Mass of earth (Me) = 100 × Mass of moon (Mm)
Radius of earth (Re) = 4 × Radius of moon (Rm)
Since the mass and radius of moon is less than that of the earth therefore, moon exerts lesser \(\frac {1}{6}\)th force of attraction on the object. Hence the weight of the object on moon is \(\frac {1}{6}\)th of the weight of the same object on earth.

Question 7.
Why is it difficult to hold a school bag having a strap made of thin and strong string? (Imp.)
Answer:
We know force per unit area is called pressure i.e. P = \(\frac {F}{A}\). Now for the constant force, the pressure experienced is inversely proportional to area. Now, when the string is thin, it has less area of cross-section and hence, exerts greater pressure on the hand for the given weight of school bag. Thus, it becomes difficult to hold the school bag.

PSEB 9th Class Science Solutions Chapter 10 Gravitation

Question 8.
What do you mean by buoyancy?
Answer:
Buoyancy means upward thrust acting in a body when the body is completely or partly immersed in a fluid (i.e. liquid or a gas).

Question 9.
Why does an object float or sink when placed on the surface of water?
Answer:
When the object has density less than the density of water i.e. 1 gm/cm3 then it, floats on the surface of water, because, it displaces more weight of water than its own weight. The upward force applied by displaced water is called buoyant force. As buoyant force is more than its own weight, therefore, it floats.

When the object has a density of more than 1 gem-3, then it sinks in water, because, it always displaces less weight of water than its own weight. As buoyant force is less than its own weight, therefore, it sinks.

Question 10.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Answer:
With a weighing machine, we find weight and not mass, Your weight as noted by the machine is 42 kg f (or 42 kg wt) and not 42 kg. The actual weight is more than 42 kg. since you have displaced some air when weighed in it. However, the mass will remain the same in all cases.

Question 11.
You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than the other. Can you say which one is heavier and why?
Answer:
The bag of cotton will actually be heavier than the iron bar. Cotton is bulky and has more area as compared to the area of the iron bar. Due to more area occupied by cotton bags, it experiences more upthrust because of the displaced volume of air. This upthrust reduces the downward pull and hence its weight as recorded by the weighing machine will be lesser.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

This PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ In a chemical reaction, old bonds in the reactants are broken forming new bonds to give products.

→ A chemical equation represents a chemical reaction.

→ By using chemical formulae instead of words, chemical equations can be made more useful and concise.

→ According to the law of conservation of mass matter (or Mass) can neither be created nor destroyed in a chemical reaction.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ If the number of atoms of each element is the same on both sides of the arrow in a chemical reaction then the chemical equation is a balanced equation.

→ The method used to balance chemical equations is known as the Hit-and-Trial method since we make trials to balance the equation by using the smallest whole number coefficient.

→ The solid, gas, liquid, and aqueous states of reactants and products are represented by the notations: (s), (g), (l), and (aq) respectively.

→ When reactants and products are present as solutions in water then the word aqueous (aq) is written.

→ When (g) is written with water, it means that water is present in the form of vapour.

→ A reaction in which two or more reactants combine to form a single product is known as a combination reaction.

→ The chemical formula for marble is CaCO3.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ After two three days of whitewashing, calcium carbonate is formed which gives a shiny finish to the walls.

→ We get energy from food.

→ During digestion, food is broken into fine particles of simpler substances.

→ The decomposition of vegetable matter into compost is an example of an exothermic reaction.

→ A reaction in which a single reactant breaks down to give simpler products is called a decomposition reaction.

→ On heating, crystals of ferrous sulfate crystals lose water, and their color changes.

→ NO2 fumes are brown in colour.

→ The white colour of silver chloride changes into a grey colour in sunlight.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ The chemical reactions in which energy is given out are called exothermic reactions.

→ Those reactions in which energy is absorbed are known as endothermic reactions.

→ Those reactions in which there is an exchange of ions between the reactants are called double displacement reactions.

→ Those reactions in which precipitates are formed are known as precipitate reactions.

→ If in a reaction one of the reactants gets oxidized and the other gets reduced, then such a reaction is called a redox reaction.

→ In a reaction, a substance is oxidized when there is a gain of O2 or a loss of H2 in it.

→ A substance is reduced when it gains H2 or loses O2.

→ When a metal comes in contact with acid or moisture around it, gets corroded and the process is called corrosion.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ Examples of corrosion are black coating on silver and green coating on copper.

→ Oxidation of oils and fats become rancid and their taste and smell change.

→ To slow down the oxidation process of food materials these are kept in air-tight containers.

→ Chemical change: It is a reaction in which new substances are formed. It is called a chemical change.

→ Chemical reaction: A process in which chemical change takes place is called a chemical reaction.

→ Reactants: Those substances which take part in a chemical reaction are called reactants.

→ Products: Those substances which are formed in a chemical reaction are called products.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ Combination reaction: It is a chemical reaction in which two or more two substances combine to form a single substance.

→ Decomposition reaction: It is a chemical reaction in which a molecule breaks into molecules of simpler substances.

→ Displacement reaction: A reaction in which a substance displaces another substance is called a displacement reaction.

→ Double displacement reaction: This is a reaction in which there is a mutual exchange between two different atoms or groups of atoms.

→ Neutral solution: When an acid and a base are mixed in a proper proportion, then we get a neutral solution.

→ Neutralisation reaction: When we get salt and water as the only products by mixing acid and base, then such a reaction is known as a Neutral reaction.

→ Oxidation: A substance is oxidized when there is a gain of oxygen or a loss of hydrogen in the substance.

→ Reduction: A substance is reduced when there is a loss of oxygen and a gain of hydrogen in the substance.

→ Redox reaction: A reaction in which oxidation and reduction both take place simultaneously is called a redox reaction.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ Exothermic reaction: Those reactions in which heat is produced along with the products are called exothermic reactions.

→ Endothermic reactions: Those reactions in which heat is absorbed are called endothermic reactions.

→ Precipitation reactions: When two solutions are mixed and due to reaction between them a white coloured substance (or some other colour) is formed which is insoluble in water, then this is called a precipitation reaction.

→ Fermentation: The change of carbonic substances with the help of microorganisms or enzymes into simple carbonic substances is called fermentation.

→ Rancidity: When fat/oil-containing food materials are left for a long time then due to oxidation there is a change in their smell and taste, this change is called rancidity.

→ Reducing agent: That substance that gets oxidised itself or reduces the other substances by giving electrons is called a reducing agent.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ Oxidizing agent: That substance that gets reduced itself or oxidizes the other substances by gaining electrons is called an oxidizing agent.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

This PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

→ During the 19th and 20th centuries, many changes came in the European society and it is said that Sociology originated to study such changes.

→ From the 17th-19th centuries, many philosophers wrote new books which gave a great contribution to the emergence of sociology. Montesquieu and Rousseau are quite important among them.

→ Auguste Comte was a French philosopher and is considered as the Father of Sociology.

→ He wrote a book ‘The Course on Positive Philosophy’ in which in 1839, he used the word ‘Sociology’. He called it a science of society.

→ Comte gave the theory of Positivism and said that social phenomenon can also be understood with scientific explanation and positivism is that method.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

→ So, positivism is the systematic method of observation, experience, comparison, and historical method with which society can be scientifically studied.

→ Comte studied different societies and said that to reach the present stage, society had to cross through three stages and these stages are the Theological stage, Metaphysical stage, and Positivistic stage. This is Comte’s law of three stages.

→ Karl Marx was a German Philosopher who is known for his views given on class and class struggle.

→ The concepts of communism and socialism were also given by Karl Marx.

→ Marx was of the view that the history of society, is the history of class struggle.

→ There exist two classes in all the societies-capitalist class which owns all the means of production and labour class which is not having anything to sell except its labour.

→ There is the existence of conflict between the both to get more and this is known as class struggle.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

→ Emile Durkheim is also known as one of the founding fathers of sociology.

→ He tried to establish sociology as a science. He was the first professor in the subject of sociology.

→ Durkheim gave a great contribution to the subject of sociology and some of the important concepts given by him are the concept of Social Fact, Theory of Suicide, the theory of Division of Labour, the Concept of Religion, etc.

→ Durkheim was of the view that the concept of division of labour existed in society right from ancient times.

→ The nature of society is determined due to the division of labour.

→ Max Weber is one of the important sociologists and founding fathers of sociology.

→ Like Marx, he was also a German Philosopher.

→ He gave many concepts to sociology such as the concept of social action, Verstehen, Protestant Ethics and Spirit of Capitalism, Authority and its types, Bureaucracy, etc.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

→ Class: Group of people whose means of production are common.

→ Authority: It is a form of power supported by the norms of a social system and accepted as legitimate by those who participate in it.

→ Social Action: It is an act that cares about the actions and reactions of individuals. If the acting individual takes account of others’ behaviour, it is social.

→ Class Consciousness: The awareness among members of a class about their common motives.

→ Class Struggle: There exists a conflict of interests between capitalist and labour classes. This conflict of interests becomes a reason for class struggle. When class consciousness increases among the people, class struggle also increases.

→ Positivism: In positivism, it is considered that society acts according to certain rules which can be discovered.

→ Mechanical Solidarity: The sense of unity among the members of a homogeneous society is called mechanical solidarity.

PSEB 11th Class Sociology Notes Chapter 12 Western Sociological Thinkers

→ Organic Solidarity: In many societies, people have differences among them and that’s why they depend upon each other. The unity which exists in such a society is known as organic solidarity.

PSEB 11th Class Sociology Notes Chapter 11 Social Change

This PSEB 11th Class Sociology Notes Chapter 11 Social Change will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 11 Social Change

→ Change is the law of nature. There is nothing in this world that has not yet changed. Even nature changes itself from time to time.

→ When change comes in different parts of society and the change affects the structural change comes in the ways of living of the people.

→ There are many features of social change such as it is a universal process, speed of changes is different in different societies, it is community change, no prediction regarding change is possible, it is the result of many interactions, it can be planned as well as unplanned, etc.

PSEB 11th Class Sociology Notes Chapter 11 Social Change

→ There are many types of social change such as evolution, development, progress, and revolution.

→ Many a time these words are used for each other but in Sociology, they are very much different from each other.

→ The meaning of evolution is equal change internally. This is a very slow process and social institutions change from simple to complex.

→ Development is also an aspect of social change.

→ When change comes in anything in the desired direction, it is known sis development.

→ Different sociologists have given different bases of development.

→ Progress is another type of social change. It means to move towards achieving objectives.

→ Progress is the efforts made to achieve objectives which is definite and which get scope ration from social values.

PSEB 11th Class Sociology Notes Chapter 11 Social Change

→ Revolution brings a sudden and fast change in society with which old structure comes to an end and new structure comes forward.

→ Many a time people become so dissatisfied that they stand up against the system. It is known as revolution.

→ The revolution of 1789 A.D. in France was a change of such type.

→ Many factors influence the direction and speed of social change such as natural factors, beliefs, and values, social reforms, demographic factors, technological factors, educational factors, etc.

→ Diffusion: The process by which cultural traits spread from one culture to another.

→ Innovation: Introduction of new ideas, techniques, etc., and better use of existing ideas and technology.

→ Social Change: Change in the functions of social structure and social system.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

This PSEB 11th Class Sociology Notes Chapter 10 Social Stratification will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

→ Inequality exists everywhere in society, Someone is black, white, poor, rich, thin, fat, literate, or illiterate. There are many other bases which we can find in our society.

→ Divison of society in different layers on different bases is known as social stratification.

→ We cannot find any society where stratification doesn’t exist.

→ It exists everywhere in ancient societies, medieval societies, and modern societies.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

→ Stratification has many features such as is a universal process, is social in nature, its type is different in different societies, relations in it are based on superiority and inferiority.

→ Mainly four forms of stratification are available in our societies and these are caste, class, feudalism, and slavery.

→ Indian society is greatly influenced by the caste system.

→ A caste is an endogamous group that keeps certain restrictions on its members regarding relationships, social intercourse, etc. The caste of an individual was fixed according to his birth.

→ In modern societies, a new form of stratification has come forward and this is the class system.

→ Class is a group of people who are similar to each other on a particular basis.

→ For example, upper class, middle class, lower class, labour class, industrialist class, doctor class, etc.

→ Feudalism was one of the important aspects of medieval European society.

→ One individual was given a very large piece of land and was made feudal lord.

→ This land was transmitted to his children with which they remained rich.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

→ During the 19th and 20th centuries, slavery prevailed in many parts of the world.

→ One person was purchased and sold as a slave and the owner kept unlimited rights over him.

→ G.S. Ghurye was one of the Indian sociologists who gave his views on the caste system.

→ According to him, the caste system is so complex that it is not possible to define it.

→ That’s why he gave six features of the caste system.

→ After the Indian independence, many changes came in the caste system and the changes are still going on.

→ Now caste system is declining day by day.

→ Caste restrictions no more prevail, caste privileges come to an end, constitutional provisions provide equality to all and all these factors have played a very important role in the decline of this system.

→ Many factors contributed to bringing changes in the caste system such as socio-reform movements, modern education, urbanisation, modernisation, industrialisation, development of means of transport and communication, constitutional provisions, etc.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

→ Mainly three types of classes prevail in our society: Upper class, middle class, and lower class. The difference between these classes is mainly on the basis of wealth.

→ A caste is a closed group which cannot be changed in any case but a class is an open group that can be changed with an individual’s ability and hard work.

→ According to Karl Marx, in different ages, there prevailed two classes.

→ The first one is the capitalist class and the second one is labour class.

→ The conflict remained there, between them, all the time and this is known as class conflict.

→ New trends are also coming into the class system. During the last few decades, a new class has emerged and this is the middle class.

→ The upper class always exploited the lower class with the help of the middle class.

→ Varna: During ancient times, society was divided into many parts on the basis of Occupation, and each part was known as varna. There were four Varnas-Brahmin, Ksljatriya, Vaishya, and Shudra.

→ Caste: An endogamous group that keeps certain restrictions on its members regarding social intercourse.

PSEB 11th Class Sociology Notes Chapter 10 Social Stratification

→ Class: The economic group which can be differentiated from the other economic group on any basis.

→ Feudalism: During the medieval period, there prevailed a very powerful system in the medieval European society in which one person was made a feudal lord by giving a large piece of land. He was authorized to collect tax from the farmer.

→ Stratification: The process of dividing society into different layers on different bases is known as stratification.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

This PSEB 11th Class Sociology Notes Chapter 9 Social Structure will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

→ There are many basic concepts of sociology and social structure is one of them.

→ Herbert Spencer was the first Sociologist who used the word social structure.

→ After him, many other Sociologists such as Talcott Parsons, Radcliffe Brown, Maclver, etc. also wrote about it.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

→ Society has many parts which are connected in. one way or the other. All these parts are interrelated.

→ The systematic form of these interconnected parts is known as social structure.

→ All these parts are abstract but they direct us in one way or the other.

→ Social structure has many features. For example, it is abstract, it has many inter-related parts, one system exists in all of its parts, it regulates our behaviour, it is universal, it expressed the exterior form of society, etc.

→ Herbert Spencer wrote a book ‘The Principles of Sociology’ in which he used the word social structure and compared it with the living body.

→ He was of the view that the way in which different parts of the human body are needed for its smooth functioning, in the same way, different parts of social structure play a very important role in its smooth functioning.

→ There are several elements of social structure and status and role are quite important among all.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

→ The meaning of status is the position given to an individual while living in society.

→ One person is given many a status such as officer, father, son, President of a club, etc.

→ Status is of two types – Ascribed and Achieved.

→ Ascribed status is that which one gets automatically without any effort.

→ Achieved status is that which one gets due to his efforts and ability.

→ The role is the collection of expectations that are expected to be fulfilled by an individual.

→ Many roles are attached to each status. Only with the role, we come to know that how anyone will act while sitting on a particular status.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

→ There are many features of the role such as it is learned, it is the functional aspect of status, it has a psychological base, etc.

→ Status and role are deeply related as they are the two sides of the same coin.

→ If anyone is given a status then automatically role is attached with the status.

→ Without a role, status is of no importance and without status, the role cannot be performed.

→ Social Structure: Orderly arrangement of different parts is known as social structure.

→ Role Set: When someone gets many roles.

→ Role Conflict: When an individual gets many roles and a conflict starts among them.

→ Role: The expected behaviour of an individual who holds a particular status.

PSEB 11th Class Sociology Notes Chapter 9 Social Structure

→ Status: Status is the social position of an individual which he needs to obey.

→ Ascribed Status: The status which one gets on the basis of birth.

→ Achieved Status: The status which is achieved through skill and talent.

PSEB 7th Class Maths Solutions Chapter 4 Simple Equations Ex 4.2

Punjab State Board PSEB 7th Class Maths Book Solutions Chapter 4 Simple Equations Ex 4.2 Textbook Exercise Questions and Answers.

PSEB Solutions for Class 7 Maths Chapter 4 Simple Equations Ex 4.2

1. Write the first step that you will use to separate the variable and then solve the equation.

Question (i).
x + 1 = 0
Answer:
Given equation x + 1 = 0
Subtracting 1 from both sides, we get
x + 1 – 1 = -1
or x = – 1

Question (ii).
x – 1 = 5
Answer:
Given equation is x – 1 = 5
Adding 1 to both sides we get
x – 1 + 1 = 5 + 1
or x = 6
Thus x = 6 is the solution of the given equation

Question (iii).
x + 6 = 2
Answer:
Given equation is x + 6 = 2
Subtracting 6 from both sides, we get:
x + 6 – 6 = 2 – 6
or x = – 4
Thus, x = – 4 is the solution of the given equation.

Question (iv).
y + 4 = 4
Answer:
Given equation is y + 4 = 4
Subtracting 4 from both sides we get
y + 4 – 4 = 4 – 4
or y = 0
Thus, y = 0 is the solution of the given equation.

PSEB 7th Class Maths Solutions Chapter 4 Simple Equations Ex 4.2

Question (v).
y – 3 = 3
Answer:
Given equation is y – 3 = 3
Adding 3 to both sides we get
y – 3 + 3 = 3 + 3
or y = 6
Thus, y = 6 is the solution of the given equation.

2. Write the first step that you will use to separate the variable and then sotye the equation :

Question (i).
3x = 15
Answer:
Given equation is 3x = 15
Dividing both sides by 3 we get
\(\frac{3 x}{3}=\frac{15}{3}\)
or x = 5

Question (ii).
\(\frac{P}{7}\) = 4
Answer:
Given equation is \(\frac{P}{7}\) = 4
Multiplying both sides by 7, we get
7 × \(\frac{P}{7}\) = 7 × 4
or p = 28
Thus, p = 28 is the solution of the given equation.

Question (iii).
8y = 36
Answer:
Given equation is 8y = 36
Dividing both sides by 8, we get
\(\frac{8 y}{8}=\frac{36}{8}\)
or y = \(\frac {9}{2}\)

Question (iv).
20x = – 10
Answer:
Given equation is
20x = – 10
Dividing both sides by 20
\(\frac{20 x}{20}=\frac{-10}{20}\)
or x = \(\frac {-1}{2}\)

PSEB 7th Class Maths Solutions Chapter 4 Simple Equations Ex 4.2

3. Give the steps you will use to separate the variable and then solve the equation.

Question (i).
5x + 7 = 17
Answer:
Given equation is 5x + 7 = 17
Subtracting 7 from both sides, we get
5x + 7 – 7 = 17 – 7
or 5x = 10
Dividing both sides by 5, we get
\(\frac{5 x}{5}=\frac{10}{5}\)
or x = 2

Question (ii).
\(\frac{20 x}{3}\) = 40
Answer:
Given equation is \(\frac{20 x}{3}\) = 40
Multiplying both sides by 3, we get
3 × \(\frac{20 x}{3}\) = 3 × 40
or 20x = 3 × 40
Dividing both sides by 20, we get
\(\frac{20 x}{20}\) = \(\frac{3 \times 40}{20}\)
or x = 6

Question (iii).
3p – 2 = 46
Answer:
Given equation is 3p – 2 = 46
Adding 2 to both sides, we get
3p – 2 + 2 = 46 + 2
or 3 p = 48
Dividing both sides by 3, we get:
\(\frac{3 p}{3}=\frac{48}{3}\)
or p = 16

PSEB 7th Class Maths Solutions Chapter 4 Simple Equations Ex 4.2

4. Solve the following equations :

Question (i).
10x + 10 = 100
Answer:
Given equation is 10x + 10 = 100
Subtracting 10 from both sides, we get
10x + 10 – 10 = 100 – 10
or 10x = 90
Dividing both sides by 10, we get
\(\frac{10 x}{10}=\frac{90}{10}\)
or x = 9
Thus x = 9 is the solution of the given equation.

Question (ii).
\(\frac{-p}{3}\) = 5
Answer:
Given equation is \(\frac{-p}{3}\) = 5
Multiplying both sides by – 3, we get
– 3 × \(\frac{-p}{3}\) = -3 × 5
or p = -15
Thus p = – 15 is the solution of the given equation.

Question (iii).
3x + 12 = 0
Answer:
Given equation is 3x + 12 = 0
Subtracting 12 from both sides, we get
3x + 12 – 12 = – 12
or 3x = – 12
Dividing both sides by 3, we get
\(\frac{3 x}{3}=\frac{-12}{3}\)
or x = -4
Thus x = – 4 is the solution of the given equation.

PSEB 7th Class Maths Solutions Chapter 4 Simple Equations Ex 4.2

Question (iv).
2q – 6 = 0
Answer:
The given equation is 2q – 6 = 0
Adding 6 to both sides, we get
2q – 6 + 6 = 0 + 6
or 2q = 6
Dividing both sides by 2, we get
\(\frac{2 q}{2}=\frac{6}{2}\)
or q = 3
Thus, q = 3 is the solution of the given equation.

Question (v).
3p = 0
Answer:
The given equation is 3p = 0
Dividing both sides by 3, we get
\(\frac{3 p}{3}=\frac{0}{3}\)
or p = 0
Thus, p = 0 is the solution of the given equation.

Question (vi).
3s = -9
Answer:
The given equation is
3s = -9
Dividing both sides by 3, we get
\(\frac{3 s}{3}=-\frac{9}{3}\)
or s = – 3
Thus, s = – 3 is the solution of the given equation.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

This PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ There exist many institutions in our society. In social institutions, we can include marriage, family, and kinship.

→ Except for social institutions, there are many other institutions such as political, religious, economic, educational, etc.

→ Political System is a sub-system of society. It fixes such human roles which are necessary to maintain law and order in society. There is a great relationship between polity and society.

→ In Sociology, information on political institutions is used to understand many concepts such as power, leadership, authority, etc. Such political institutions help us in maintaining peace and security in society.

→ Power is the ability of individuals or groups to carry out their will even when opposed by others.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ A definite and fixed amount of power exists in society.

→ Few groups have more power and they exercise their power over the group which is having less power.

→ Power is applied with the help of an authority. Authority is a form of power that is considered just and legitimate.

→ Those who have authority, use power because they consider it justified.

→ Different societies have different states. In a few societies, there is no concept of state and they are considered stateless societies.

→ Such states existed in ancient societies. In modern societies, authority is included in the concept of state and it is obtained from the people.

→ Max Weber gave three types of authority-traditional, legal and charismatic.

→ Father’s authority is traditional, Government’s authority is legal, and accepting any leader’s will is called charismatic authority.

→ The state is the basic institution of the political system. It has four essential elements and these are population, geographical area, sovereignty, and government.

→ There are three organs of government and these are-Legislature, Executive, and Judiciary.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ To maintain State and government, a proper balance between these three organs is necessary.

→ The present-day political system runs with democracy. It is of two types—direct and indirect.

→ In a direct democracy, people decide on their own and in indirect democracy, people’s elected representatives make all the decisions.

→ The government in our country has adopted the decentralized system and govts, are made till local level.

→ In rural areas, Panchayat is established at the village level, Block Samiti at the block level, and Zila Parished at the district level and they are responsible for doing development in their respective areas.

→ In a democracy, political parties keep a very important place.

→ A political party is a group of people whose main objective is to attain power by contesting elections.

→ Few parties are national parties and few are regional parties.

→ Interest groups keep a very important place in a democracy.

→ They are attached to any particular group and they work to achieve the interests of their group.

→ Religion has existed in society since the time when human society started.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ Religion is nothing but faith in super-natural power that is beyond our existence and reach.

→ Many religions exist in our country India such as Hinduism, Islam, Christianity, Sikhism, Buddhism, Jainism, Zoroastrianism (Parsi), etc.

→ India is a multi-religious country where people of many religions live in peace and harmony with each other.

→ Every person needs money to buy food, cloth, house, health services, etc. and all these are important parts of our economy. Economic institutions take care of our income and expenditure.

→ Different societies have different economies. Few societies have collective economies, few are pastoral economies, rural economies, industrial economies, and capitalist economies. Karl Marx also gave a new economy called socialist economy.

→ The concept of division of labor is not new to our society.

→ When people start to do specific work and are unable to do all the works, it is called specialisation and division of labour.

→ The caste system and Jajmani system in India are one such type of division of labour.

→ If we observe our society, we can say that nothing in our society, is possible without education.

→ Education changes an uncivilized person into a civilized individual.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ Education is of two types – formal and informal.

→ Formal education is that which we get in school, college, etc. and informal education is that which we get from our daily life experiences.

→ Authority: Power established by the political system in its geographical area.

→ Division of Labour: The system in which occupations are divided into different parts and every occupation is given to an individual or group.

→ Economy: System of production, distribution, and consumption.

→ Globalisation: The process of international integration arising from the interchange of world views, ideas, products, and other aspects of culture.

→ Totem: Considering any tree, plant, stone, or any other thing as sacred.

→ State Society: The society in which formal organisation of government exists.

→ Stateless society: The society in which there is no formal organisation of government.

PSEB 11th Class Sociology Notes Chapter 8 Polity, Religion, Economy and Education

→ Pressure groups: Such groups in a democratic system work for the interests of a particular group.

→ State: State is a group with four essential features – population, geographical area, sovereignty, and government.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

This PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

→ Every society forms a few institutions to fulfill the basic needs of its member.

→ The institution is a structure of the social system which directs the individual behaviour of a community.

→ It fulfills a few basic needs which are very much necessary for social existence.

→ There are certain features of institutions such as they fulfill particular needs.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

→ They are collections of rules, they are abstract, universal, social, and permanent. They cannot be changed very easily.

→ Marriage is one such institution that exists in every society. It is one of the basic social institutions.

→ With marriage, two individuals of opposite sexes are permitted to live with each other as husband-wife.

→ They establish sexual relations, produce children and contribute to the continuation of society.

→ Many types of marriages exist in our society but monogamy and polygamy are quite famous.

→ Polygamy is further divided into two parts, polygamy, and polyandry. Polyandry type of marriage exists in tribal society and polygamy existed in our society some time ago.

→ Many rules of mate selection prevail in our society out of which endogamy and exogamy are quite common.

→ In endogamy, one needs to marry within a particular group and in exogamy, one needs to marry out of a particular group.

→ During the last few decades, many changes have come in the institution of marriage.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

→ Many reasons are there behind these changes such as industrialisation, urbanisation, modern education, new laws, freedom of women, the impact of western societies, etc.

→ Family is one such universal institution that exists in almost all societies.

→ Individual life is greatly affected by family and one cannot live without one’s family.

→ Family is having many features such as it is a universal institution, it is small in size, it is both permanent and temporary, it controlling individual behaviour.

→ There are many types of family that can be divided on the basis of authority, place of living, members, etc.

→ During the last few decades, changes have also taken place in the institution of the family such as small in size, breaking up of families, change in the status of women, changes in functions, etc.

→ Kinship is a system of human relationships and many relations are included in it. Kinship can be divided into two bases—affinal and consanguinity.

→ On the basis of nearness and distance, there are three types of kins-primary, secondary and tertiary.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

→ Primary relatives are father, mother, brother, sister.

→ Secondary kins are primary kins of our primary kins such as the father of father- grandfather.

→ Tertiary kins are primary kins of our secondary relatives such as the son of uncle-cousin.

→ Patriarchal: The family in which authority and control are in the hands of the father.

→ Matriarchal: The family in which authority and control are in the hands of the mother.

→ Nuclear Family: The family in which husband, wife, and their unmarried children live.

→ Joint Family: The family in which members of more than two generations live under one roof and eat in a common kitchen.

→ Endogamy: Marriage within a particular group i.e. caste.

→ Exogamy: Marriage out of a particular group, i.e. family, gotra, etc.

PSEB 11th Class Sociology Notes Chapter 7 Marriage, Family and Kinship

→ Monogamy: Marriage of one male with one female.

→ Polygamy: Marriage of one male or female with many females or males.

→ Affinal kinship: This type of kinship is made after marriage such as son-in-law.

→ Consanguineous kinship: This type of kinship is made due to blood and right after birth i.e. son, brother, sister, etc.

→ Kinship: Social relations, real or imaginative, made according to marriage or blood.

PSEB 11th Class Sociology Notes Chapter 6 Socialization

This PSEB 11th Class Sociology Notes Chapter 6 Socialization will help you in revision during exams.

PSEB 11th Class Sociology Notes Chapter 6 Socialization

→ When a child takes birth, he is unaware of his surroundings. Gradually, he becomes older and learns the ways to live in society. This process of learning ways of living in society is known as socialisation.

→ The process of socialization starts with the birth and goes on for the whole of one’s life.

→ The life of an individual comes to an end but this is a never-ending process.

PSEB 11th Class Sociology Notes Chapter 6 Socialization

→ If there will be no process of socialization, humans will start behaving like animals and there will be nothing called society.

→ The process of socialisation is a never-ending process. Gradually a child grows older, becomes independent and at this stage, this process becomes quite necessary.

→ At this stage, a need is required to control his behaviour. Here the advantage of socialisation is visible to us.

→ There are five stages of the socialization-infant stage, childhood stage, Adolescent stage, Adulthood stage, and old age.

→ The infant stage starts with birth and goes till one year. The childhood stage goes till 13-14 years, the adolescent stage till 17-18 years, the adulthood stage from 18-50 years, and old age start after this.

→ There are many agencies to complete the process of socialisation and these can be divided into two parts-formal and informal.

PSEB 11th Class Sociology Notes Chapter 6 Socialization

→ Family, playgroup, religion, etc. come under informal agencies. Law, legal system, political system, etc. are included informal agencies of socialisation.

→ Socialisation: A continuing process in which an individual acquires a personal identity and learns the values, norms, behaviour, and social skills appropriate to his/her social position.

→ Self: The distinct identity of an individual.

→ Play Group: A group of people, having the same age, background, and social status, with whom individual associates and who are likely to influence his beliefs and behaviour.

→ Formal means of Socialisation: Those means of socialisation, also known as institutional means, provide formal socialisation such as school, law, political system, etc.

PSEB 11th Class Sociology Notes Chapter 6 Socialization

→ Informal means of Socialisation: These means of socialisation are also known as social group agents which include individual and social institutions that socialise an individual in an informal manner.