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Q1. What is meant by Matter?
Ans: MATTER:
Any thing which has mass and occupied space is called Matter.
Example:
Table, book, earth and etc.
Q2. Give the molecular theory of Matter?
Ans: MOLECULAR THEORY OF MATTER:
i. According to this theory, matter is made of tiny particle called Molecules and
atoms.
ii. The molecules of matter are in c continues and rapid motion.
iii. The difference between solid, liquid and gases states are due to the distance
between the molecules and due to violent motion of the molecules.
Q3. How many state of matter are?
Ans: There are three state of matter.
(i) Solid (ii) Liquid (iii) Gas
Q4. Give the molecular theory of Solid.
Ans: MOLECULAR THEORY OF SOLID:
I. In solids, the molecules are closely packed due to the strong force of attraction.
II. Molecules cannot move freely but they can move to and fro about their mean
position.
iii. Solids have definite volume and shape due to their force of attraction and very
Tiny space between them.
iv. It is not easy to compress solid but they broken down.
Q5. Give the molecular theory of Liquids.
Ans: MOLECULAR THEORY OF LIQUIDS:
i. The liquid molecules can move freely from one place to another place as
compared to solids.
ii. Liquids have definite volume due to some force of attraction between their
molecules, but no definite shape due to weak force of attraction between their
molecules.
iii. The distance between liquid molecules is larger as converted to solid molecules.
Q6. Give the molecular theory of Gases.
Ans: MOLECULAR THEORY OF GASES:
I. Gases have no definite shape and volume because of very large distance
between their molecules and very least force of attraction between their
molecules.
ii. The force of attraction can be negligible between gases molecules due to this
the gases molecules can freely move from one place to another.
iii. The molecules of a gas collide with one another and with the walls of the
container and exert pressure on the walls.
iv. Gases expand on heating because the kinetic energy of molecules is increased
and distance between them is also increased.
Q7. Differentiate between solids, Liquids and Gases.
Ans: SOLIDS LIQUIDS GASES
(i) They have definite shape and volume.
(ii) The molecule of solids have vibratory motion.
(iii) They have greater .density.
(iv)The distance between molecules solids is
very short (i)They have definit volume but
not shape.
(ii)The molecules of liquids have random motion.
(iii)They have low density as compared to solids.
(iv)The distance between Molecules of liquids is greater than solids. (i)They have not definite shape and volume.
(ii)The molecules of gas moves in a straight line.
(iii)They have very low density as compared to solids and liquids.
(iv)The distance between Molecules of gases is much
Greater than solids & liquids.
Q8. What is meant by Brownian motion?
Ans: Brownian motion:
In 1827, a scientist named Robert Brown observed
the movement of dust particles in air seem to very
irregular motion. He also observed the movement
of pollen grains suspended in water with a microscope
and noticed that they were continuously moving in
zig zag path as shown in figure. The zig zag motion
of these particles is called Brownian motion.
Q9. Define Elasticity and Elastic Limit with example.
Ans: Elasticity:
First Definition:
If we apply a force to pull rubber band, it is stretched. When the force is removed. The rubber band comes to its originals shape. This behaviour of any body is called Elasticity.
Second Definition:
Such characteristic of matter in which it tends to oppose every deforming force is
called Elasticity.
Examples:
(i) If a wooden meter rod can bent into an arc by applying force. When force is
removed, it straightens
(ii) Similarly, elasticity is also present in steel rod.
ELASTIC LIMIT:
If we bent a wooden meter into an arc and increases our force then at certain stage the
wooden meter can be break. It means we reached at the elastic limit of wooden meter.
So, it is defined as:
“Such maximum force applied by a body to oppose, every deforming force is called
elastic Limited.”
If we increase our force from elastic limit of a body then it does not comes to its
original position.
Q10. Explain elasticity of bodies on the basis of molecular theory.
Ans: EXPLANATION OF ELASTICITY:
i. Due to very small distance between the molecules of a solid, there is quite strong force between the molecules and they are closely packed..
ii) If a certain force is applied on a body ,then it changes the place of molecules.
Therefore, change in shape volume or length may take place. When force is withdrawn the molecules may become the original place due to strong internal
molecular force of attraction.
iii) Elasticity of a body depends upon the nature of a body. For example, the force,
of attraction between rubber molecules is less as compare to steel. So, less force
is required to deformate rubber as compared to steel..
Q11. Define deformation. Explain with the types.
Ans: DEFORMATION:
If a force is applied on a body to change the shape, then that state is called Deformation.
TYPES OF DEFORMATION:
Linear Deformation:
If a force is applied on a body to change in length, then this state is called Linear
Deformation.
Cubic Deformation:
If the volume of a body change due to applying force, then that state is called Shearing
Deformation.
Q12. Define Stress. Give its unit in different systems.
Ans: STRESS:
When a force is applied to change the length, volume or shape of a body. The value of
This force per unit area is called Stress.
OR
“The magnitude of force applied per unit area of the body is called Stress.”
Mathematically:
It a force “F” Newton is applied on unit area “A”. The stress can be written as
Stress = Force
Area
 = F
A
Where  Greek word is called “ETA”.
SYSTEMS UNITS OF STRESS
S.I.System
C.G.S. System
B.E - System Newton / metre2 or N/m2
Dynes / centimetre2
Lbs / ft 2

Q.13. Write the types of Stress.
Ans: There are three types of Stress.
i. Linear Stress.
ii. Cubic Stress.
iii. Surface Stress.
1. Linear Stress:
When change in length of a body, due to stress is called Linear Stress.
2. Cubic Stress:
When change in length, width and height of a body due to stress is called Cubic Stress.
3. Shearing Stress:
When change in surface of a body due to stress is called Shearing stress.
Q14. What is meant by Strain and Longitudinal Strain?
Ans: STRAIN:
“Such change in volume, length or shape produced by Stress is called Strain.”
LONGITUDINAL STRAIN:
The ratio between the change in length and original length is called Longitudinal Strain
or Linear Strain.
Mathematically:
If “L” is the original length and “ I “ is change in length of a body then,
Strain = Change in Length
Original Length
Strain = I / L
Where “Є” denotes Strain.
Є = I /L
UNIT:
Strain has not unit because it is a ratio between two similar quantities.
Q15. Differentiate between Stress and Strain.
Ans:
STRAIN STRESS
1. It is the ratio between changed in
length per unit original length.
2. It is a ratio between two quantities,
3. It has no unit.
4. Its formula is ∊ = ∆L/L 1. The force per unit area of a body is
called stress.
2. It is a scalar quantity.
3. In S.I system, its unit is N/m2
4. Its formula is  = F
A
Q16. State Hook’s law. Explain with the help of Graph.
Ans: SATEMENT:
The law state the within elastic limit the deformation of body is directly proportional to
the force producing it. “ OR “
In an elastic limit, Stress is directly proportional to strain the relation is called Hook’s
Law.
Mathematically:
Stress  Strain
Stress = Cons tan t (Strain)
Constant = Stress
Strain
Hook’s law also defined as “The force acting on a body is directly proportional to
Deformation within elastic limit.”
F  -x
F = kx
Where “k” is Hook’s constant and x is deformation.
EXPLANATION OF HOOK’S LAW BY GRAPH:
In this graph, if we increase stress then strain will also increase. Even a body reaches to
A point “ x “ , here elasticity maintained. If stress kept continues then the body will go to
Plastic region. It means elasticity of elastic body finished. In plastic region, we increased
More stress then the body will break. The point is called Breaking point. The above
Graph proved the following point.
i. Stress is directly proportional to Strain.
ii. More Stress finished the elasticity of a body.
iii. To known about elasticity of a body.

Q17. State the law of Young’s Modulus and verify Hook’s law.
Ans: YOUNG’S MODULUS:
The ratio between Stress and Longitudinal strain is called Young’s Modulus.
Mathematically:
Young’s Modulus = ____ Stress _
Longitudinal Strain
Y = 

 = ∆L
L
 = F
A
So, equation (i) becomes,
Y = 
¬ ∈
Y = F ÷ AL
A L

Y = F X L
A AL
Y = FL
A ∆L1
Where Y is denoting Young’s Modolus.

VERIFICATION OF THE HOOK’S LAW
According to Hook’s law
Stress  Strain
E  AL
A L
For an elastic limit, the above equation becomes
F = K L
A L
F = AK L
L
F = AK L Where AK = constant
L L
F = (Constant) L
F  L
Q18. Write the characteristics of stationary liquids.
Ans: Characteristics of Stationary Liquids:
i. The pressure exerted by the liquid acts perpendicular to the walls of vessel in
which it is kept.
ii. Pressure exerted on the liquid is transmitted equally in all directions.
iii. In liquids, the pressure at the same depth is equal in all directions.
Q19. Define and explain Pressure. Give its unit in different system?
Ans: Pressure:
The perpendicular force acting on the unit area of a body is called Pressure.
Explain:
i. If we push a drawing pin with a sharp pointed tip into a piece of wood. It will
penetrate the wood.
ii. Under the tip of the drawing pin the force is very high on the small area of the
tip of the pin. Hence it penetrates into the wood.
iii. Now it is difficult to cut things with a blunt knife because the area of the blunt
edge of the knife is relatively more and the force over this area is less as
compared to the sharp edge.
Mathematically:
Pressure = Force / Area
P = F / A
SYSTEM UNITS OF PRESSURE
M.K.S. System
S.I. System
C.G.S. System
B.E. System Newton / metre2 or N/m 2
Pascal (Pa)
Dynes / centimeter 2
Lbs/ft 1






Q20. What is meant by Pressure of Liquids and on what factors does it depend?
Ans: PRESSURE OF LIQUIDS:
Water contained in a glass has weighed. As the weight is a force what acts downward,
therefore the water exerts a pressure on the bottom of the glass. Similarly, every liquid
exerts force per unit area of container, which is called Pressure of Liquid.
Pressure of Liquids depends upon following factors:
i. Density of Liquid:
If a liquid more dense then pressure is more.
ii. Depth of Liquid:
If the depth of liquid is greater than the pressure is greater.
Q21. Prove that the pressure of liquids depends upon density and depth or P = phg.
Ans: Suppose water contained in a gas, exerts force per unit area is called Pressure. If “F” is
force, “A” is area and Pressure is “P” then.
P = F / A ________________1
We know that
F = mg ________________2
Mass per unit volume is called Density and it is denoted by (RHU) OR “p “
P = m / V
M = Pv
The volume is, V = Length x Width x Height
V = L x W x h
V = A x h
So, m = P (A x h) put in equation – No.2
F = mg
F = P (A x h)g
Now put the value of “F” in equation No.1
P = p (A x h)g
A
P = phg
Where “p” is density, h = depth, g = acceleration due to gravity. Hence it proved the
pressure of liquid depends upon depth and density.

Q22. Give the principle of Pascal.
Ans: PRINCIPLE:
According to this principle, if a pressure is applied to a liquid contained in a vessel, it is
transmitted pressure equally in all direction and acts perpendicularly to the walls of the
container. This was discovered by Blaise Pascal, and is known as Pascal’s Principle.
Explanation:
It is explain with the help of following experiment.
Experiment:
i. Take a vessel which is connected with four
Similar pistons.
ii. Fill it with water.
iii. Apply a force to one end of the pistons.
iv. The other three pistons simultaneously
move through small distance outwards.
v. Thus it can be proved that the pressure
has been transmitted in all directions
throughout the water.

Q23. How many types of Hydraulic Machines.
Ans: TYPES OF HYDRAULIC MACHINES:
There are three types of Hydraulic Machines.
i. Hydraulic Break system.
ii. Hydraulic Lifts.
iii. Hydraulic Press.

Q24. What do you know about Hydraulic break system.
Ans: HYDRAULIC BREAK SYSTEM:
System is used in vehicle,
consists of a master cylinder joined by
tubes to four smaller cylinder, one for
each wheel of vehicle. The master
cylinder and each of the brake cylinders
are provided oil tight pistons.
When we push on the brake pedal it
causes a force on the piston in the
master cylinder. This pressure
transmits equally in all directions.
This pressure effects the points present in the wheel cylinder. These pistons force the
brake shoes to expand and resulting friction stops the wheel. It is an example of
Pascal’s Law.
Q25. Write note on Hydraulic Press.
Ans: HYDRAULIC PRESS:
The working of hydraulic press is same
hydraulic lift, in a hydraulic press the
piston ‘B’ is used to compress any material
over it a rigid roof material is placed
between roof and piston ‘B’. When force is
applied on piston ‘n’ then B moves upwards.
It compresses cotton into a compact bale.
Q26. Write short note on Hydraulic lift.
Ans: HYDRAULIC LIFT:
In Hydraulic lift, narrow cylinder ‘A’ connected with wider cylinder B and they are fitted
with air tight pistons.











It is filled with some incompressible fluid. By pressing cylinder ‘A’, the pressure is
transmitted equally according to Pascal’s principle to the piston of the cylinder ‘B’ and
B moves upward. The piston ‘B’ is used as a platform for a car or any heavier object to
be lifted.
Q27. What is meant by Pressure of gases? On what factor it depends?
Ans: PRESSURE OF GASES:
When a gas is closed in a cylinder in a container, then molecules of gas collide with
each other and also strike against the walls of the container. During collision, the
molecules exert force per unit area of container, this force is called Pressure of gases.
FACTORS ON WHICH PRESSURE OF GASES DEPENDS:
The pressure of gases depends upon the following two factors:
i. Volume of Gas
If the volume of gas is greater then pressure is increased.
ii. Temperature of Gas
If the temperature of a gas is increased then the molecules of gas collide with
The walls firstly and exerted greater pressure on the walls of container.
Q28. Explain Atmospheric pressure. Give also the experiment of Von Guericke.
Ans: ATMOSPHERIC PRESSURE:
The air is mixture of Nitrogen, Oxygen and many other gases. These gases exerts
pressure is called Atmospheric pressure.
The density of air changes from sea level to different altitudes. It is most dense at sea
level, its density decreases with increase of height above sea level.
At sea level the pressure of air is about 100,000 Pa. We do not normally feel
atmospheric pressure as the pressure inside our bodies is almost the same as that
outside.

EXPERIMENT OF VON GGUERICKE:
i. The existence of atmospheric pressure
was first performed by a German scientist
Von Guericke.
ii. He took two hollow metallic hemispheres
which were made to fit with each tightly.

iii. Air inside the hemispheres was removed
through a small hole by means of an air pump.
iv. It was found that the hemispheres could not be pulled apart when the air had
been removed.
v. The hemispheres were so tightly hold that it looks two teams each of eight
horses to separate them.

Q29. What is barometer and how many types of Barometer are.
Ans: BAROMETER:
A device for measuring the atmospheric pressure is called barometer. There are two
types of Barometer.
(i) Mercury Barometer (ii) Aneroid Barometer

Q30. Write a note on Mercury barometer.
Ans: MERCURY BAROMETER:
Atmospheric pressure is measured in a laboratory
by a device called Mercury Barometer.
CONSTRUCTION:
A barometer consists of a thick walled glass tube
1 meter length which is opened at one end and
closed from the other side. To start with the tube
is filled with mercury. The open end is firmly covered
with a thumb and then carefully inverted in a vessel
containing mercury. Some of the mercury from the
leaving a space at the closed end. It is found to be
approx. 760 mm. The length of mercury in tube equal
to the atmospheric pressure.

Q31. Write note on Aneroid Barometer.
Ans: ANEROID BAROMETER:
The aneroid barometer is commonly used for household i purposes. It consists of a
corrugated steel box ‘A’ partially evacuated of air. The top of the box pressure against
a strong spring ‘S’. If the air pressure rises, the top of the bon is pressed inwards and
If the pressure decreases the top moves upwards. The movement of the top due to
changes in pressure is magnified by a system of lever connected to a small rod fixed on
the top of ‘A’. The movement of the lever enables a printer ‘P’ to move over a suitable
calibrated scale.
Q32. Write the application of atmospheric pressure.
Ans: The following are uses of atmospheric pressure.
(i) It is used to make siphons. Ii) It is used to make pumps.
(iii) It is used to make syringes.
Q33. State Archimedes Principle.
Ans: ARCHIMEDES PRINCIPLE:
When a body is wholly or partially immersed in a liquid, then a force acts on the lower
surface of the body, this force equal to the volume of body and called upward thrust.
So, a body immersed in a liquid it experiences and upward thrust equal to the weight
of the liquid these its weight is decreased in water. This principle was first observed by
Archimedes. So it called Archimedes Principle.
Q34. Give the experimental proof of Archimedes Principle.
Ans: EXPERIMENTAL PROOF OF ARCHIMEDES PRINCIPLE:
For experimental verification of Archimedes Principle, consider the following experiment.
Consider a cylindrical object of area ‘A’ and height ‘h’ immersed in a liquid of density p;
four sides for acting on that body in which two from left and right and other two
from up and downward. The force acting from left and right cancel the effect of each
other and also up downward forces do the same. The force acting upon surface of a body.
The force acting upon surface of a body F1 = Ah1pg + Apa
The force acting lower the surface of the body.
F2 = Ah2pg + Apa
Upthrust = F2 F1
Upthrust = (Ah2pg + Apa) - (Ah1pg + Apa
Upthrust = Ap2pg + Apa Ah1pg – Apa
Upthrust = Ah2 pg - Ah1pg
= Ap(h2 h1)g
= Aphg
= pg(I x h x w )
= pgV
We know that Mass
density = volume
p = m
V
PV = m
Put the value in equation (i)
Upthrust = pVg
= mg
Upthrust = W W = mg
Uthrust = Weight of the body.
We can now draw the following conclusions for floating bodies in fluids.
i. The up-thrust force depends upon density an volume.
ii. Up-thrust force equal to the weight of the body.
iii. These results prove Archimedes Principle.
Q35. Write the conditions fro the floatation of the bodies.
Ans: CONDITIONS:
i. If the weight of the body is greater than the upward thrust the body will sink in
the liquid which is providing upward thrust.
ii. If the weight of body is less than the upward thrust, the body will rise up and
float on the surface of the liquid..
iii. If the weight of the body is equal to the upwards thrust the body will float
partially immersing into the liquid.
Q36. Explain why an Iron ship floats while a piece of stone sinks in water.
Ans: A ship is constructed in ship in such a way that the density of the ship be will less than
the density of water displaced by it to move over. The volume of ship is very large and
hence the upward thrust on it is also very large. This upward thrust not only neutralizes
the weight of ship but provides some additional upward force on the ship. The ship,
therefore, does not sink in water.
A piece of stone sinks in water because its weight is greater than the upward thrust of
water.
Q37. Write the condition for the motion of submarines in water.
Ans: CONDITION FOR THE MOTION OF SUBMARINES IN WATER:
Submarines can float on the surface of water and when is needed they can dive in
water. Submarines are fitted with large hollow ballast tank. To dive in water, the
submarine takes water into its hollow tanks. This increases the weight of submarine and
it submerges in water.
Diving submarine: