The document discusses the thermal expansion of solids and its various applications. It begins by defining thermal expansion as the increase in dimensions of a substance when it is heated. There are three types of thermal expansion: linear, superficial, and cubical. Gravesande's ring and ball experiment is described as demonstrating how solids expand on heating. Several real-world applications of the thermal expansion of solids are then outlined. Linear expansion is applied in mounting wheels on carts and laying railroad tracks. Superficial expansion allows tight lids to be removed from jars and nails to pass through holes in metal plates. Volumetric expansion is used in riveting metal plates together and in the construction of aircraft to account for expansion during flight

1. 1
Uses of Bacteria
in
Food Industry
Real World Application
of Thermal Expansions
of Solids

2. 2
INTRODUCTION
Democritus Leucippus
Democritus Leucippus
 Thermal Expansion
- It is a well-known phenomenon now that substances
expand on heating and contract on cooling. If you heat a
body, it alters its dimensions. Depending on the shape of
the body.
- The expansion produced in the matter due to the
absorption of heat energy is called Thermal Expansion.
- Whenever, any substance ( solid, liquid, or gas) is
heated, its volume increases. The expansion in matter is
divided into three classes :
1. Linear Expansion : The increase in length of a solid
when heated, is called linear expansion.
2. Superficial Expansion: The increase in area of a solid
when heated is called superficial expansion.
3. Cubical Expansion: The increase in volume of a
substance ( solid, liquid& gas) when heated is called
cubical expansion.

3. 3
Expansion of Solids – An Experiment
Gravesande’s Ring and Ball Experiment
 Ring and ball apparatus in a 1912 scientific instrument
catalog for performing Gravesande's experiment, a simple
experiment demonstrating thermal expansion.
 It consists of a small metal ball suspended by a chain from a
stand, with a metal ring below it.
 The external diameter of the ball is equal to the internal
diameter of the ring, such that the ball can easily pass
through the ring.
 The ring is made just big enough so when both pieces are at
the same temperature, the ball fits through the ring. However,
when the ball is heated by dipping it in boiling water, or
playing a spirit lamp flame over it, the metal expands and it
can no longer fit through the ring.
 From the above experiment, it is concluded that the solids
expand on heating.
 Now allow the ball to cool to room temperature and it can be
seen that the ball again pass through the ring. This proves,
that the solids contract on cooling.

4. 4
4
Uses of Bacteria
in
Food Industry
Real World Application
Of
Thermal Expansions
of
Solids

5. 5
Application of Linear Expansion of Solids
Linear expansion is the expansion in the length of the substance which
is subjected to increasing temperature. Linear expansion mostly takes
place in solids.
Applications :
Mounting of Iron Rim on Wooden cart Wheel :
The Iron rim to be mounted on wooden cart wheel has a slightly smaller
diameter than wooden wheel. The iron rim is heated so that it expand.
When its size becomes larger than wooden wheel it is slipped on the
wheel. After that cold water is poured on the wheel so that on cooling
the rim contracts and holds the wooden wheel tightly.
It is for the same reason, the Tonga drivers pours cold water over iron
rims during hot summer which prevents the iron rim from loosening its
grip over the wooden wheel.
Laying of Rail Tracks:
Rails are made of steel, which expands on heating and contract on
cooling. If rails are fixed tightly leaving no space for expansion or
contraction, these will bend outward in summer and will result in
derailment of trains.
To avoid this, small gaps are left between the rails. The rails are then
joined by fishplates. In summer the gaps get smaller and winter bigger,
but rail by itself remains straight.

6. 6
Application of Linear Expansion of Solids
The clocks regulated with pendulum require adjustment during
summer and winter:
The pendulum of clocks expand in summer and contract in winter,
therefore, they lose time in summer and gain time in winter. In order
that the clocks should give correct time, the pendulums are made
from invar which is an alloy having vey small coefficient of linear
expansion in some clocks, compensating pendulums are used.
A compensating pendulum is made of a number of iron and brass
rods joined in such a way that the length of pendulums remains
contacts even if there is a change in temperature.
Mounting of Bridges:
The girders supporting the bridge are not fixed in the walls of the
pillars.it is because they expand on heating and contract on cooling
and in doing so, can break pillars, then the bridge can collapse.
Because of this, the girders are mounted on rollers, leaving a small
space in between for expansion or contraction. That’s how the
bridge is saved from a possible collapse.
It is for the same reason that small spaces are left behind the walls,
while mounting the girders. So as to allow for expansion and
contraction.

7. 7
Application of Linear Expansion of Solids
Laying of Telephone and Electric Transmission Line :
The metallic wires tend to expand during summer and sag down.
They may come in contact with other wires during storm, causing a
serious breakdown. In winter they contract and can break.
Thus, when the telephone or telegraph wires are laid in summer,
they are kept slightly loose so as to allow for contraction in winter.
Similarly, if they are laid in winter they are kept very tight so as to
allow expansion during summer.
Laying of Cement Floor:
Cement floor is not laid as one block. It is because it expands
during summer. As there will not be any space for expansion,
therefore, it will crack. Instead floor is laid in small blocks leaving a
very small space in between the blocks. This is in turn, allows for
expansion, and hence the floor does not crack.
Breaking of Glass :
When milk is poured into a thick walled glass vessel at room
temperature, the inner surface of the vessel gets expanded, while
the outer surface remains at room temperature. Thus there is no
expansion on the outer surface. Due to uneven expansion in the
vessel, the glass cracks.

8. 8
Application of Linear Expansion of Solids
Bimetallic Strip and Fire Alaram :
 Plates of two different metals which are riveted together at a
number of points in such a way that they can not slide on being
heated or cooled for a “Bimetallic Strip”.
 The bimetallic strip figure shows a brass-invar ( an alloy of iron)
at room temperature in straight position. When this is heated, the
brass expands more as compared to invar. This unequal
expansion bends the strip, the brass takes the outer edge of the
bend and invar takes the inner edge of the bend.
 On cooling the bimetallic strip below the room temperature, the
brass contracts more than the invar. Thus the bimetallic strip
bends and the invar takes the outer edge of the bend and brass
takes the inner edge of the bend.
Application:
 Automatic Fire Alarm
- The bimetallic strip is used in Fire Alarm. Incase of fire the
bimetallic strip gets heated and bends. The brass expands more
than invar and rise up and a electrical contact is established
resulting the bell starts ringing giving an alarm.
- Bimetal thermometers work on the principle that different
metals expand at different rates as they are heated. They are
used in Oven, air conditioner in industrial apparatus like refineries,
hot wires, heater, tempering tanks etc.

9. 9
Application of Superficial Expansion of Solids
Superficial Expansion of Solid :
 When it gets heated, its length and breadth get expensive.
This is nothing but superficial expansion. an increase in the
dimension(only length and breadth) of the body because of
heating is known as superficial expansion. So an increase in
area that is length and bread on heating is called a
superficial expansion.
Removing Tight Lids of Glass Jar:
 To open the lid of a glass jar that is tight enough, it is
immersed in hot water for a minute or so. Metal cap expands
and loose. It would now be easy to turn it to open.
 The high temperature water causes the metal lid and glass
jar to expand. But glass has a low coefficient expansion than
the material of the lid. Hence the lid expands more than the
glass jar and the lid can be easily removed.
To Pass a Nail Through Hole in Metal Plate:
 To pass nail thorugh a metal plate having a hole of a
diameter slightly less than that of the nail, the plate is heated.
So that the diameter of hole increases and the nail can easily
pass through it.

10. 10
Application of Volumetric Expansion of Solids
Volumetric Expansion of Solid :
 Volumetric expansion is the expansion in the volume of the
substance which is subjected to increasing temperature. For
an open solid, volumetric expansion refers to the expansion
of the volume enclosed by it.
Application:
Riveting of two Metal Plates:
 Two metal plates can be jointly tightly together by a process
called riveting. Rivets are heated to red hot condition and are
forced through coaxial holes in the two plates. The end of hot
rivets is then hammered and shaped. On cooling, the rivets
contracts and bring the plates tightly gripped to each other.
Design of Air Craft:
The aircraft expands by 15-25 centimeter during its flight due to
increase in temperature on account of heat created by friction
with air. Designers used rollers ( separators) to isolate the cabin
and passenger area from the body of aircraft so that the
expansion does not rip the plane apart.

11. 11
Thank You
Bibliography :
1) https://thefactfactor.com/facts/pure_science/physics/applications-of-expansion-of-solids
2) https://www.vedantu.com/question-answer/name-three-types-of-thermal-expansion
3) https://www.sciencedirect.com/topics/engineering/linear-coefficient-of-expansion
4) https://en.wikipedia.org/wiki/Thermal_expansion
5) https://www.google.com/search?bih=577&biw=1280&sxsrf=AOaemvKloXSH0_ilW9sW92
h3uB5FyU2jgQ:1632141184036&source=univ&tbm=isch&q=thermal+expansion+of+solid
s&hl=en-GB&sa=X&ved=2ahUKEwidh_3bx43zAhVG7XMBHSiVCF4QjJkEegQIIRAC
6) https://ncert.nic.in/ncerts/l/keph203.pdf
Acknowledgement:
I wish to express my deep gratitude and sincere thanks to the Principal, Mrs Sudha Menon,
North Point School for her encouragement and facilities that she provided for this project work.
I extend my hearty thanks to Mrs.Gauri Kulkarni Physics teacher, who guided me to the
successful completion of this project. I take this opportunity to express my deep sense of
gratitude for her invaluable guidance, constant encouragement, immense motivation, which
has sustained my efforts at all the stages of this Project work…
I can’t forget to offer my sincere thanks to parents and also to my sister who helped me to
carry out this project work successful and for their valuable advice and support, which I
received from them time to time….