MATTER
CH 10
X-PHYSICS
FAHAD AKHTER
MATTER:
“Any thing which has some mass and occupies some volume is called matter.”
*Matter exist in three states Solid, Liquid & gas.
KINETIC MOLECULAR THEORY OF MATTER:
i.
ii.
iii.
iv.
Matter is composed of tiny particles called molecules.
Molecules are constantly in motion. Their K.E depends upon temperature.
Molecules attract each other with a force which decreases as the distance between increases.
On heating Kinetic energy of molecules increases and the force between them decreases.
BROWNIAN MOTION:
Introduction:
Robert Brown in 1827 used tiny particles such as pollen grains to observe the motion of liquid molecules.
Definition:
“The zig zag motion of tiny suspended particles in liquid and gases is known as Brownian motion.”
ELASTICITY:
“The property of matter through which its regain to its original size or shape as soon as external force is
removed is called elasticity.”
STRESS:
“The opposing force per unit area exerted by the body to resist a change in its size or shape is called
stress.”
𝐅𝐨𝐫𝐜𝐞
𝐒𝐭𝐫𝐞𝐬𝐬 =
𝐀𝐫𝐞𝐚
Unit:
𝛔 =
In S.I system unit of stress is N/m2.
𝐅
𝐀
STRAIN:
“The frictional change in length, volume or shape produced by a given stress is known as strain.”
*Strain is a ratio of two similar quantities therefore it has no unit.
Longitudinal or Linear strain:
“The change in length of a body is called longitudinal strain.”
𝐋𝐨𝐧𝐠𝐢𝐭𝐮𝐝𝐢𝐧𝐚𝐥 𝐬𝐭𝐫𝐚𝐢𝐧 =
𝐂𝐡𝐚𝐧𝐞 𝐢𝐧 𝐥𝐞𝐧𝐠𝐭𝐡
𝐎𝐫𝐢𝐠𝐧𝐚𝐥 𝐥𝐞𝐧𝐠𝐭𝐡
If ∆L is the change in length, L is the original length then longitudinal strain ∈ is:
∈=
∆𝐋
𝐋
COMPARISON OF ELASTICITIES OF TWO SUBSTANCES:
Consider two elastic substance ‘x’ and ‘y’ in the form of wires, they have the same length and same area of
cross section. Suppose that ∈x and ∈y is the strain produced in the x and y respectively.
By definition
∈𝐱=
𝛔
𝛔
𝐚𝐧𝐝 ∈ 𝐱 =
∈𝐱
∈𝐲
X-PHYSICS
FAHAD AKHTER
𝐖𝐡𝐞𝐫𝐞 𝛔 = 𝐬𝐭𝐞𝐬𝐬 𝐚𝐩𝐩𝐥𝐢𝐞𝐝.
∈𝐱
𝛔/∈ 𝐱
∈𝐲
=
=
∈𝐲
𝛔/∈ 𝐲
∈𝐱
𝐈𝐟 ∈ 𝐱 > ∈ 𝐲, 𝐭𝐡𝐞𝐧
∈x < ∈y
Thus we conclude that a body with smaller strain is more elastic then the body having the larger strain
when the applied stress same.
ELASTIC LIMIT:
“The maximum force per unit area for which the body regains its original position is called elastic limit.”
HOOK’S LAW:
“With in elastic limit stress is directly proportional to strain.”
Stress 𝜶 Strain
𝑺𝒕𝒓𝒆𝒔𝒔
= 𝑪𝒐𝒏𝒔𝒕𝒂𝒏𝒕
𝑺𝒕𝒓𝒂𝒊𝒏
𝛔
= 𝐂𝐨𝐧𝐬𝐭𝐚𝐧𝐭
∈
YOUNG’S MODULUS:
“The ratio between stresses to the longitudinal strain is called Young’s modulus.”
𝐒𝐭𝐫𝐞𝐬𝐬
𝐋𝐨𝐧𝐠𝐢𝐭𝐮𝐝𝐧𝐚𝐥 𝐬𝐭𝐫𝐚𝐢𝐧
𝐘𝐨𝐮𝐧𝐠’𝐬 𝐦𝐨𝐝𝐮𝐥𝐮𝐬 =
𝐘 =
𝐘 =
𝐘 =
𝛔
∈
𝐅
𝐋
𝐱
𝐀 ∆𝐋
𝐅𝐋
𝐀∆𝐋
*S.I unit of young’s modulus is N/m2.
HOOK’S LAW APPLIED TO A HELICAL SPRING:
“Tension is proportional to extension If ‘F’ stands for tension and ‘x’ stands for extension,
then:
F 𝜶 –x
F = -K x
Where ‘K’ is known as spring constant.
PRESSURE:
“Force per unit area is called pressure.”
𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞 =
𝐅𝐨𝐫𝐜𝐞
𝐀𝐫𝐞𝐚
X-PHYSICS
𝐏 =
FAHAD AKHTER
𝐅
𝐀
Unit:
S.I unit of pressure is Pascal (Pa) or N/m2.
ATMOSPHERE:
The atmosphere is the blanket of air around the earth. It extends up to about 1000 km above the surface of
earth. Since air is a kind of matter, has weight. The total weight of atmosphere corresponds to its mass of
about 4.5 x 1018 Kg.
At high altitudes like mountains is less which causes difficulties in breathing and nose bleeding May also
occurs.
ATMOSPHERIC PRESSURE:
“The pressure exerted by the weight of the atmosphere on the surface is called atmospheric
pressure
BAROMETER:
“The device used to measure the atmospheric pressure is called barometer.”
 At sea level its value is about 105 Pa.
 The standard pressure is sometime called one atmosphere (1 atm) or one bar.
PRESSURE IN LIQUID:
The pressure exerted at any point on area ‘A’ is given by:
𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞 =
𝐅𝐨𝐫𝐜𝐞
𝐀𝐫𝐞𝐚
∴Force = Weight
𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞 =
𝐖
𝐀
∴W = Ah𝝆g
𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞 =
𝐀𝐡𝛒𝐠
𝐀
P = h𝛒g
PASCAL’S PRINCIPLE:
“When an external pressure applied is applied on a stationary liquid
then the liquid transmits undiminished equally in all direction and acts
perpendicular to the walls of the container.”
APPLICATIONS OF PASCAL’S PRINCIPLE:



Hydraulic brake system.
Hydraulic lift.
Hydraulic Press.
X-PHYSICS

HYDRAULIC BRAKE SYSTEM:
CONSTRUCTION:
It consists of a master cylinder provided
with an oil tight piston which is connected
to the brake paddle. Each wheel of the
car is provided with a smaller cylinder with
an oil tight piston in it. These cylinders are
connected through tubes to the master
cylinder. Suitable oil (Brake oil) filled in this
tube.
WORKING:
When brake paddle is pressed excess
pressure in this master cylinder is
transmitted equally to all the cylinders in
which piston moves outward thus pressing
the brake shoe against the inner surface of
the wheel a large friction force is setup
which tends to stop the wheel. As soon as
the paddle is released spring brings the
brake shoe brake to its original position.

HYDRAULIC LIFT:
In a hydraulic lift a platform is
attached to an oil tight piston which
moves in a wide cylinder. This
cylinder is connected to a smaller
cylinder which is also provided with
an oil tight piston. A suitable
incompressible liquid is filled in the
two cylinders external pressure is
applied on the smaller piston which is
transmitted into equally, due to
which the platform lift heavy object
lying on it.

HYDRAULIC PRESS:
Hydraulic press is a similar to the hydraulic lift except that in a
hydraulic press a rigid roof is provided above the platform. Any
soft material such as cotton place on the platform can be
compress.
FAHAD AKHTER
X-PHYSICS
FAHAD AKHTER
ARCHIMEDES PRINCIPLE:
“When a body is wholly or partially immersed in a liquid it experiences an up thrust which equal to weight
of the liquid displaced.”
APPLICTION OF ARCHIMEDES PRINCIPLE:
i.
ii.
iii.
To find out the specific gravity.
To find out the Density of oil.
To find out the Density of cork.
BOUNYANCY OR UPTHRUST:
“A body immersed in a liquid it experience an upward force exerted by molecules of the liquid. This
upward force is called up thrust or buoyancy of the liquid.”
* If weight of a body is greater than the up thrust then the body sinks in the liquid.
* If weight of the body is less than the up thrust the body will float on the liquid.
* If weight of a body is equal to the up thrust the body will float partially immersing in the liquid.
SURFACE TENSION:
“Surface tension is the property of a liquid by virtue of which the free surface of a liquid behaves like a
stretched-membrane tending to decrees the surface area.”
FLUID FRICTION (VISCOSITY):
The friction between any fluids like air or liquid is called fluid friction or viscosity.”
Consider any layer lying at a distance x from the stationary surface. Let A be the area of the layer moving
with the velocity v. It is found that the backward dragging force acting on any layers found to vary as:
F 𝜶 A
F 𝜶 V
F 𝜶 1/x
By combining above equations
𝑭 = −𝜼
𝑨𝒗
𝒙
Where η is the constant depending on the nature of the liquid and is known as the co-efficient of viscosity.
COEFFICIENT OF VISCOSITY:
“The coefficient of viscosity is numerically equal to the retarding force required to maintain velocity of 1m/s
relative to stationary layer.”
COEFFICIENT OF VISCOSITY:
Unit of co-efficient of friction is POISE.
POISE:
“The coefficient of viscosity is said to be one poise if the backward dragging force required maintaining
relative velocity of 1m/s between two layers each of area 1m2 and separated by a distance of 1m is 1N.”
X-PHYSICS
CH 01
FAHAD AKHTER
MULTIPLE CHOICE QUESTIONS (MCQ’S)
1. The S.I unit of strain is
i) Pascal
ii) Newton
2. The S.I unit of Pressure is
i) Pascal
ii) Newton
iii) Newton-meter
iv) None of them
iii) Newton-meter
3. The molecules of the solid is
i) Very close to each other
ii) Vary far to each other
4. The molecular theory of matter was experimentally testified by
i) Hooks
ii) Archimedes
iii) Robert-Brown iv) Pascal
5. One calorie is
i) 4.2
ii) 0.42
joule.
iii) 4200
6. Evaporation takes place at the
i) 00C
ii) 1000C
iii) All temperature
7. A force on a unit area of a solid tends or to produce deformation in solid is called
i) Pressure
ii) Stress
iii) Strain
8.
The property of solid by virtue of which a solid body covers its original shape after the removal of
applied force called
i) Elasticity
ii) Plasticity
9. According to molecular theory of matter the molecules of matter is always remain in
i) Brownian motion
ii) Vibratory motion
10. The irregular motion of small suspended particles is called
i) Circular motion
ii) Brownian motion
CH 01
PAST TEN YEARS QUESTIONS

(2003)
Q: State the following laws: I) Hook’s law.

(2004)
Q: State Pascal’s principle and write its three applications.

(2005)
Q: State the following laws/principles. I) Hook’s law
II) Archimedes principle.

(2006)
Q: State Pascal’s principle and describe the construction and working of the hydraulic press with
diagram.
Q: State the following law I) Pascal’s principle.
Q: State Hook’s law and define the formula of Young’s modulus with the help of this law.

(2008)
Q: State Pascal’s principle and explain the working of the hydraulic brake system with the help of
diagram.
Q: State the following law I) Pascal’s principle.
Q: Define the following terms: I) Elasticity
X-PHYSICS
FAHAD AKHTER

(2009)
Q: State the following laws/principles.
I) Archimedes’ principle.
Q: Define Stress. Strain and state Hook’s law and write the formula of Young’s modulus of elasticity.

(2010)
Q: State Pascal’s principle. Describe any one of its application.

(2011)
Q: State the following laws/principles. I) Hook’s law

II) Archimedes principle.
(2012)
Q: State the Pascal’s principle and writ three uses in daily life.
Avoid negative sources, people things and habits.