SUBTOPIK 9.3 PRINCIPLE OF EXPANSION AND CONTRACTION OF MATTER

CHAPTER 9
HEAT

PREPARED BY CIKGU HUSRITA

9.3 PRINCIPLE OF EXPANSION AND CONTRACTION OF MATTER

• EXPANSION AND CONTRACTION IN SOLID
• When an object is heated:

a) particles have more energy,
b) particle vibrate faster and move further apart from one

another
c) distance among particles increases,
d) the volume increases
e) solid expand

• When an object is cooled:

a) particles loss energy,
b) particle vibrate slower and move closer to one another
c) distance among particles decrease,
d) the volume decrease
e) solid contract

EXPANSION AND CONTRACTION OF SOLIDS :
METAL BALL

Ring

Metal ball

At room temperature After the metal ball is
the metal ball can heated, it expands
and cannot pass
easily slip through the through the ring
ring

9.3 PRINCIPLE OF EXPANSION AND CONTRACTION OF MATTER

• EXPANSION AND CONTRACTION IN LIQUID
• When an object is heated:

a) particles have more energy,
b) particle move faster and further apart from one

another
c) distance among particles increases,
d) the volume increases
e) liquid expand

• When an object is cooled:

a) particles loss energy,
b) particle move slower and closer to one another
c) distance among particles decrease,
d) the volume decrease
e) liquid contract

EXPANSION AND CONTRACTION OF LIQUIDS :
MERCURY

Mercury Thermometer

Wire xxxxxxxxx Beaker Ice Mercury
gauze level
Tripod Cold drops
Bunsen stand water
burner

Mercury inside a Mercury inside the
thermometer rises thermometer drops
because mercury in the because mercury in the

bulb expands bulb contracts

9.3 PRINCIPLE OF EXPANSION AND CONTRACTION OF MATTER

• EXPANSION AND CONTRACTION IN GAS
• When an object is heated:

a) particles have more energy,
b) particle move faster, randomly and further apart from one

another
c) distance among particles increases,
d) the volume increases
e) gas expand

• When an object is cooled:

a) particles loss energy,
b) particle move slower and closer to one another
c) distance among particles decrease,
d) the volume decrease
e) gas contract

EXPANSION AND CONTRACTION OF GASES :
AIR INSIDE THE FLASK

Retort Drop of Drop of Air
stand coloured coloured Water
water moves
water down the

Hand tube

Ice

The drop of coloured The drop of coloured
water rises up because water moves down
because air inside the
air inside the flask is
heated and expands flask contracts

APPLICATION OF EXPANSION AND
CONTRACTION OF MATTER

Thermometer Fire alarm

Application of
expansion and
contraction of matter

Gaps in railway Overhead cables
tracks and
bridges

APPLICATION OF EXPANSION AND
CONTRACTION OF MATTER

Thermometer
• Mercury used in the thermometer expands and contracts

according to the temperature changes

Fire alarm Copper Screw Sprinkler

• When the circuit exposed to Iron
heat from a fire
Battery
• The copper strip will expand
faster than the iron strip

• Cause the strip to bend
towards the contact point.

• The circuit system compete
• The alarm ring

Thermostat
The bimetallic strip is also

used as a thermostat in an
electric iron

GAPS IN RAILWAY TRACKS AND BRIDGES

RAILWAY TRACK STEEL BRIDGES
• Gaps in the railway tracks allow the • There are gaps in steel bridges
• These gaps enable the bridge to
iron railings to expand on hot days
• This prevents the railway tracks from expand on hot days
• Rollers in steel bridges allow
buckling and bending when the iron bridges to expand easily when
railings expand on a hot days being heated

OVERHEAD CABLES

Overhead cables are
hung loosely between
poles so that the wires will
not snap when they
contract

SOLVING OUR DAILY PROBLEMS USING THE PRINCIPLE OF
EXPANSION AND CONTRACTION OF MATTER PRINCIPLE

The bottle lid that is The dented table tennis
tightly closed can be ball can be restored to
opened by submerging
it in hot water for a little its original shape by
submerging it in a hot
while water. This is because
the air inside the table

tennis ball expands

To place the axle into the hub of the wheel, the axle
should be cooled first in liquid nitrogen at -190ºC.

Once the axle has cooled, it is put into the hub of the
wheel. At room temperature, the axle would expand

and grip the hub strongly