Preface

MATTRAB's science textbook is the perfect medium to learn about the basic science accoarcing to the curriculum issued by CDC and secure high marks in SEE. This textbook has been designed to help all the students develop their concectual thinking and scientific skills. It is the excellent introduction to experimentation and practical application of science. This textbook might be helpful to all the teachers and students for their effective teaching learning process in an easy and enjoyable manner.

We have tried to mention everything that School's Science textbook should have with intereasting defination, pictures, numericals, exercises and so on. It is not the hidden fact that the modern era is the era of science and technology. Science is the part of world we live in and an avenue to technology. So, we have also mentioned the basic to advanced scientific facts and the skills that will be helpful to everybody in the day to day life.

In SEE, the mark distribution of 'Theoretical Exam' of total 75 marks is as follows:

S.N. | Subject Area | Marks (%) | Weighting (Marks) |
---|---|---|---|

1. | Physics | 30.00 | 23 |

2. | Chemistry | 30.00 | 23 |

3. | Biology | 30.00 | 22 |

4. | Astronomy and Geology | 10.00 | 7 |

Total | 100.0 | 75 |

Similarly the following bases should be taken for practical evaluation.

Drawing, labeling, collection of materials, observation, identification and explaining characterstics

Record of the practical work

Construction of materials ans their uses

Mini project work

Viva voce

The marking distribution of 'Practical Exam' of 25 marks are as follows:

S.N. | Particulars | Weighting (Marks) |
---|---|---|

1. | Drawing/labelling/explaining characterstics | 5 |

2. | Record of the practical work | 5 |

3. | Construction of materials ans their uses | 5 |

4. | Mini project work | 6 |

5. | Viva voce | 4 |

Total | 25 |

unit 1 FORCE

Objectives

After studying this unit,you will be able to:

- state Newton's law of Gravitation and prove it.
- differentiate between gravity and gravitation.
- differentiate between mass and weight with their units.
- measure the mass of different bodies.
- describe free fall and weightlessness.

1.1 Introduction

In our daily life,we apply a force to perform various activities.Pull, push, squeeze, stretch,etc. denote a force. The force of our hands can push or pull objects. A force can change the position and shape of a body. Simalarly, a force can change the direction of motion and speed of a moving body. However, if a force is applied to move a tree or a fixed wall, the effort will not be effective. Hence, force is a pull or push which changes or tends to change the state of rest or of uniform motion or the shape and size of the body. Force is called a vector quantity as it has both magnitude and direction. In the SI system, force is measured in Newton (N) and in the CGS system, it measured in dyne [1N = 105 dyne].

There are different types of forces such as frictional force, gravitational force, electrostatic force, magnetic force,etc. On the basis of physical proximity, forces can be classfied into two types, viz. contact force and non-contact force.

Contact forces are those which act only in physical contact with eachother. For example, frictional force, collision force, pull, push,etc. Similarly, The forces which don't involve physical contact betweent he objects but act through the space between them are called non-contact forces. For example, gravitational force, electrostatic force, magnetic force,etc. These forces come into action even though the objects are not in physical contact. The magnitude of non contact forces depends on their masses and the distance of separation. These forces increase with the increase in their masses and decrease with the incease in distance.

In this unit, we will learn about one of the important non-contact forces, i.e.,gravitational force, or gravitation.

1.2 Gravitation

Gravitation is the force of attraction that exists between any two bodies due to their masses. If the stone is raised above the ground and released, it falls towards the earth. Since the stone starts moving downwards, a force must be acting on it. The force is attributed to the attraction between the earth and the stone. It is called the force of gravity. In fact the earth attracts all the objects towards its center. It is due to the gravitational force of the earth that all objects falls towards the earth when released from certain height. The gravitational force of the earth pulls every objects towards its center. Therefore we should apply the force to lift a body from the earth's surface. It was Newton who said that every object in this universe attracts every other objects with the force called the gravitational force. For a small body, the force of gavitation is small and cannot be detected easily. Newton concluded that it is not only the earth which attracts other objects but every object in the universe attracts every oyher object. For example, two stones lying on the ground attract each other. The force of gravitation between then is very small and we don't notice any motion. However, if one the bodies has a very large mass (like the earth), the small body lying near it moves towards the bigger body.

Since the masses of the sun and the earth are very large, they exert a large force on one another. The mass of the sun is so large that even the sum of all its planets and satellites is only about 0.0015th part of the sun. It is the gravitational force between the sun and the earth which keeps the earth in uniform circular motion around the sun. Similarly, the gravitational force between the earth and the moon makes the moon revolve at uniform speed around the earth. Thus the gravitational force is responsible for the existance of solar system. The effects of gravitation can be ovserved more on liquids than on solids. The tides in the sea are due to the force of attraction, which the sun and the moon exert on the water surface in the sea. Approximately twice a month at the time of new moon and full moon, the tide's range reaches its maximum due to the effect of combined gravitational force of the sun and the moon on the earth when they lie on a straight line.

fig. 1.1 Gravitational force

Thus, gravitation is the force of attraction, which exists between two bodies of the universe due to their masses. Newton was the first person who gave the popular law in 1687 AD called Newton's universal law of gravitation.

1.3 Newton's Universal Law of Gravitation

The great physicist Sir Issac Newton profounded the law of gravitation when he saw an apple fallin from a tree. Newton's law of gravitation states, "Every body in the universe attracts every other body eith the force which is directly proportional to the product of their masses and inversely proportional to the square of distance between their centers."

Let us consider to body of mass 'm1' and 'm2' seperated by distance 'd' from their centers. If the force of attraction between them is F,

fig. 1.2

Reasonable Fact 1

Why is Newton's law of gravitation is called the universal law?

Ans: Newton's law of gravitation holds true or is applicable to all the objects present in the universe, whether the objects are terrestrial or celestial. The gravitational force between any two objects exists everywhere in the universe. Therefore, Newton's law of gravitation is called the universal law of gravitation.

Accoarding to Newton's law of gravitation,

(i) The gravitational force between two bodies is directly proportional to the product of their masses, i.e.,

F ∝ m1 * m2..........(i)

(ii) The gravitational force between two bodies is inversely proportional to the square of the distance between their centers, i.e.,

F ∝ 1/(d^{2})............(ii)

Combining (i) and (ii), we get

F ∝ m1*m2/(d^{2})

∴ G = (m1.m2)/ d^{2} [Where 'G' is called the universal gravitational constant. Its value is 6.67*10-11) Nm^{2}/(kg^{2})]

1.4 Major Consequences of Gravitational Force

1.5 Application of Newton's Law of Gravitation

Universal Gravitational Conatant (G)

Universal Gravitational Conatant (G) is the force of attraction which exists between two bodies of unit masses kept at a unit distance from their centers. 'G' is a scalar quantity. Its values remains the same throughout the universe and is independent to the nature and size ot he bodies as well as the nature of the medium between them.

fig. 1.3

F = Gm1m2/(d^{2})

If, m1 = m2 = 1kg and d = 1m, then

F = G*1*1/(1^{2})

∴ F = G

Thus, universal gravitational constant is a force of attraction between two bodies each of 1kg mass seperated by 1m apart from their centers.

1.7 SI Unit of G

Accoarding to the Newton's law of gravitation, the gravitational force acting between any two bodies is given by

F = Gm1m2/(d^{2})

This formula can be rearranged to get the expression for G as follows:

G = F(d^{2})/m1m2 = Nm^{2}/kg*kg = Nm^{2}/kg^{2}

∴ The SI unit of gravitational constant (G) is Nm^{2}/kg^{2}.

Fact File 1

The value of gravitational constant (G) is 6.67*(10-11) Nm^{2}/kg^{2}. It was calculated by Henry Cavendish by using a sensitive balance called the torsion balance in 1798 AD.

Fact File 2

If (G) by some miracle were suddenly multiplied by a factor of 10, we would be crushed to the floor by the earth's attraction and if (G) were divided by this factor, the earth's attraction would be so weak that we would be able to jump over a building easily.

1.8 Variation of Gravitation with Mass and Distance

A. When the mass of the body is doubled keeping the distance between two bodies constant

Accoarding to the Newton's law of gravitation,

F1 = Gm1m2/(d^{2})

When the mass of a body is doubled,

m1 = 2m1

Then,

F2 = G(2m1)m2/(d^{2}) = 2(Gm1m2/(d^{2})) = 2F1 [∴ F1 = Gm1m2/(d^{2})]

Hence, the gravitation between two masses is doubled when the mass of a body is doubled keeping the distance between them constant.

B. When the distance between two bodies is halved keeping the masses constant

Accoarding to the Newton's law of gravitation,

F1 = Gm1m2/(d^{2})

When the distance between two bodies is halved,

d = (d/2)

Then,

F2 = Gm1m2/((d/2)^{2}) = Gm1m2/((d^{2})/4) = 4(Gm1m2/(d^{2})) = 4F1 [∴ F1 = Gm1m2/(d^{2})]

Hence, the gravitation between two masses becomes four times the previous force when the distance between them is halved keeping their masses constant.

Worked out Neumerical 1

Calculate the gravitational force between two masses of 30 kg and 10 kg when they are kept 50 cm apart.

Solution:

Given,

Mass of one body(m1) = 30 kg

Mass of another body(m2) = 10 kg

Distance(d) = 500/100 = 5 m [Since, 1m = 100cm]

Gravitational force = ?

We have,

F = Gm1m2/(d^{2})

or, F = (6.67*10^{-11})*30*10/(5^{2})

or, F = 8*10^(-10) N

∴ The gravitational force existing between thm is 8*10^(-10) N.

Worked out Neumerical 2

Calculate the gravitational force acting on a body of mass 50 kg on the surface of the earth. The mass and radious of the earth are 8*10^{24} kg and 6400 km respectively.

Solution:

Given,

Mass of the earth(M) = 8*10^{24} kg

Mass of a body(m) = 50 kg

Distance(d) = 6400 km = 6.4*10^{6} m [Since, 1km = 1000m]

Gravitational force = ?

We have,

F = GMm/(d^{2})

or, F = (6.67*10^{-11})*(8*10^{24})*50/((6.4*10^{6})^{2})

or, F = 488.5 N

∴ The gravitational force existing between thm is 488.5 N.

Activity 1

Go to an open ground. Take a ball and throw it upward. What do you observe? It reaches the certain height and then it starts falling. What is the reason behind it?

1.9 Gravity and Gravitational Field

The earth attracts all the bodies which are near to its surface. When a ball is dropped from the a roof of a house, it falls on the surface of the earth. Simalarly, fruits fall from a tree. The force that pulls these objects downwards is the gravity of the earth. Thus, gravity is the force that pulls a body towards the center of the earth or a planet.

fig. 1.4

The SI unit of gravity is newton (N). It is a vector quantity. The gravity (F) of the earth or a planet depends on its mass (M) and radious (R). The gravity of a planet acts towards its center.

All the bodies present in the gravitational field of a earth or a planet are pulled towards the center of the planet or the planet. The gravitational field of a planet is the area around the planet upto where the gravity of the planet has its influence on an object. The gravitational field of a planet depends on the mass and radious of a planet.

The force of attraction between a planet and a body on the surface or near its surface is called gravity, or the weight of the body on that planet. So, gravity of a planet, or a heavenly body, can be calculated on the basis of Newton's law of gravitation.

Gravity (F) = Weight (W) = GMm/R² [ ∵ F = W ]

Where, F = Gravity, W = Weight of the body, M = Mass of the planet, or heavenly body, R = Radious of a planet and G = Gravitational constant.

∴ F = GMm/R²

Fact File 3

The moon has its own gravity like that of the earth and other heavenly bodies. Accoarding to scientists,the gravity of the earth is about six times more than that of moon. Thus, a body weighing 100 N on the moon weighs 600 N on the earth.

Different heavenly bodies have their own gravity. The effect of the earth's gravity is more on the body of larger mass than that on the body of smaller mass. Therefore, it becomes diffcult to lift a large stone than a smaller one. The weight of the body is the mesure of the gravity acting on the body.

Worked out Neumerical 3

Calculate the weight of a body of a mass 50 kg: (i) on the surface of the earth and (ii) on the surface of the moon. [ Given, mass of the earth = 6*10^{24} kg, mass of the moon = 7.2*10^{22} kg, radious of the earth = 6400 km, radious of the moon = 1.7*10^{3}]

Solution:

(i) On the surface of the earth,

Given,

Mass of the earth (M) = 6*10^{24} kg

Mass of the moon (m) = 7.2*10^{22} kg

Radious of the earth = 6400 km = 6400000 m

Weight of the body (F or W) = ?

We have,

F = W = GMm/R^{2}

= (6.67*10^{-11}*6*10^{24}
*50)/(6400000)^{2} [ ∵ G = 6.67*10^{-11} Nm^{2}/kg^{2} ]

= 488.5 N

∴ Weight of a body on the earth's surface is 488.5 N.

(ii) On the surface of the moon,

unit 2 PRESSURE

Objectives

After studying this unit,you will be able to:

- introduce pressure and demonstrate liquid pressure.
- state and prove Pascal's law.
- state Archimede's principle and describe its application with examples.
- solve the problem related to Pascal's law and Archimede's principle.
- introduce atmospheric pressure and explain its application.

1.1 Introduction

In our daily life,we apply a force to perform various activities.Pull, push, squeeze, stretch,etc. denote a force. The force of our hands can push or pull objects. A force can change the position and shape of a body. Simalarly, a force can change the direction of motion and speed of a moving body. However, if a force is applied to move a tree or a fixed wall, the effort will not be effective. Hence, force is a pull or push which changes or tends to change the state of rest or of uniform motion or the shape and size of the body. Force is called a vector quantity as it has both magnitude and direction. In the SI system, force is measured in Newton (N) and in the CGS system, it measured in dyne [1N = 10^5 dyne].

There are different types of forces such as frictional force, gravitational force, electrostatic force, magnetic force,etc. On the basis of physical proximity, forces can be classfied into two types, viz. contact force and non-contact force.

Contact forces are those which act only in physical contact with eachother. For example, frictional force, collision force, pull, push,etc. Similarly, The forces which don't involve physical contact betweent he objects but act through the space between them are called non-contact forces. For example, gravitational force, electrostatic force, magnetic force,etc. These forces come into action even though the objects are not in physical contact. The magnitude of non contact forces depends on their masses and the distance of separation. These forces increase with the increase in their masses and decrease with the incease in distance.

unit 3 ENERGY

Objectives

After studying this unit,you will be able to:

- introduce pressure and demonstrate liquid pressure.
- state and prove Pascal's law.
- state Archimede's principle and describe its application with examples.
- solve the problem related to Pascal's law and Archimede's principle.
- introduce atmospheric pressure and explain its application.

1.1 Introduction

In our daily life,we apply a force to perform various activities.Pull, push, squeeze, stretch,etc. denote a force. The force of our hands can push or pull objects. A force can change the position and shape of a body. Simalarly, a force can change the direction of motion and speed of a moving body. However, if a force is applied to move a tree or a fixed wall, the effort will not be effective. Hence, force is a pull or push which changes or tends to change the state of rest or of uniform motion or the shape and size of the body. Force is called a vector quantity as it has both magnitude and direction. In the SI system, force is measured in Newton (N) and in the CGS system, it measured in dyne [1N = 10^5 dyne].

There are different types of forces such as frictional force, gravitational force, electrostatic force, magnetic force,etc. On the basis of physical proximity, forces can be classfied into two types, viz. contact force and non-contact force.

Contact forces are those which act only in physical contact with eachother. For example, frictional force, collision force, pull, push,etc. Similarly, The forces which don't involve physical contact betweent he objects but act through the space between them are called non-contact forces. For example, gravitational force, electrostatic force, magnetic force,etc. These forces come into action even though the objects are not in physical contact. The magnitude of non contact forces depends on their masses and the distance of separation. These forces increase with the increase in their masses and decrease with the incease in distance.

unit 4 HEAT

Objectives

After studying this unit,you will be able to:

- introduce pressure and demonstrate liquid pressure.
- state and prove Pascal's law.
- state Archimede's principle and describe its application with examples.
- solve the problem related to Pascal's law and Archimede's principle.
- introduce atmospheric pressure and explain its application.

1.1 Introduction

In our daily life,we apply a force to perform various activities.Pull, push, squeeze, stretch,etc. denote a force. The force of our hands can push or pull objects. A force can change the position and shape of a body. Simalarly, a force can change the direction of motion and speed of a moving body. However, if a force is applied to move a tree or a fixed wall, the effort will not be effective. Hence, force is a pull or push which changes or tends to change the state of rest or of uniform motion or the shape and size of the body. Force is called a vector quantity as it has both magnitude and direction. In the SI system, force is measured in Newton (N) and in the CGS system, it measured in dyne [1N = 10^5 dyne].