thermal expansion why are small gaps
left in between rails don't know the
answer no worries we shall find the
solution hey did you notice that the
level of mercury and the thermometer
rose when it was placed in hot water you
must be wondering why this happened
right it happened because of thermal
expansion thermal expansion is the
tendency of matter to expand on heating
this tendency of expansion can be
observed in solids liquids as well as
gases now let us see how this concept of
thermal expansion applies to a
thermometer a thermometer usually
consists of a narrow tube with a small
bulb at its one end the bolt and a part
of the narrow tube is filled with
mercury which is liquid at room
temperature now when a thermometer is
placed in hot water
mercury incited expands due to thermal
expansion and as a result it's level
rises
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you must be thinking how the gasoline
came out of the tank even though it was
exactly filled to the brim am i right
new gasoline also expands on heating so
what happened is that when the tank was
filled to the brim there was no space
left in it now when the bike was kept in
the Sun the tank became hot which
eventually heated the gasoline filled in
it as a result the gasoline expanded but
since there is no space left in the tank
expansion course gasoline to come out of
the tank
[Music]
do you think that the rails vent because
of thermal expansion if yes then you are
absolutely correct a rail rape track is
made up of a number of rails joined to
each other these rails are usually made
up of steel steel expands on heating and
contracts on cooling when the rails are
joined to one another without leaving
any space for expansion the rails Bend
due to thermal expansion and the train
goes off the railway track to avoid this
the rails are not joined together firmly
and said each rail is connected to the
other in such a way that a small gap is
left in between them these small gaps
provide space for easy expansion of the
rails which happens during summer as
well as due to continuous friction
between the train wheels and the rails
hence these small gaps prevent the rails
from bending preventing any kind of
accidents
[Applause]
[Music]