Physics Explains the World

Most of the metals expand if sufficient heat is provided to them. This anomalous property of expansion is called Thermal Expansion .

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We can calculate this coefficient of thermal expansion using the formula given below,

$\alpha = \dfrac{\dfrac{\Delta L}{L_1}}{\Delta T}$

Where $\alpha$ is the coefficient of linear expansion ,

$\Delta L = L_2 - L_1$ ,

$L_1$ and $L_2$ are the initial and the final lengths and

$\Delta T$ is change in temperature .

We can define coefficient of linear expansion as follows, "It is the fractional change in the dimension per unit change in temperature, when the substance is heated or cooled"

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The coefficient of linear expansion of Iron is $\alpha_{iron} = 12×10^{-6}/K$ .

In summers, when the temperatures are high, this property of expansion, helps in curving the railway tracks.

A similar example can be seen in telegraph wires which sag more during summers, than in winters.

These gaps, which are on the order of a few millimeters across, are provided to allow room for the rails to expand in high temperatures caused by the sun as well as the friction caused by running of train.

Concept : All materials (with some exceptions) expand when heated and contract when cooled, but the amount of expansion and contraction is quite small.

How is that modern train tracks are welded together to make for stronger tracks, a smoother ride and less chance of rails coming apart? With miles of continuously welded tracks, shouldn't they buckle way up high or somewhere on a hot day?

(This is a test of the new "have a challenge master read" feature)

I've never seen gaps on train tracks in my life... maybe I'm too close to Chicago and the trains are constantly used?

These gaps are left to allow the steel tracks to expand on a hot day. The kinetic particle thoery explains it as the follow: When the temperature increases, the particles(atoms) in the steel track start to vibrate more. Thus, to provide the space needed for these 'extra' vibrations, the tracks expand in all directions. If there were no gaps left between railway tracks then due to thermal expansion the tracks would obtain a curvy nature and possibilities of a passing by train to derail would be very high.

the tracks also move when loaded trains or even empty trains pass over the tracks at high speed . You can feel the track move when long trains are coming loaded with coal here. Back and forth to an fro ,

Because of thermal expansion. ... The atoms in metals gain thermal energy and expand... L=L°(1+aplha♢t) where L is glthe new length, L° is the original length .. Aplha is the coefficient of linear expansion. APLHA is different for different metals.. ♢t is the change in temperature. ... [Note : We can use this relation in case of linear expansion. .. For area wose expansion we have to use Beta in place of Alpha...]

These gaps which are of the order of a few millimeters, are provided to allow room for the rails to expand the rise in temperature due to the atmospheric temperature as well as the friction caused by running of train.

linear expansion formula

these gaps should be obliquely made for smooth ride and those fish plates should be held together by locking nuts to prevent losing apart

The gaps you are referring to the small gaps that are left between section of the rail that form each side of the parallel railways for over which railway engines, coaches, trains and trams run.

These gaps which are of the order of a few millimeters, are provided to allow room for the rails to expand the rise in temperature due to the atmospheric temperature as well as the friction caused by running of train. All materials expand when heated and contract when cooled. the extent of expansion and contraction is quite low to be noticed by people or make much difference in most situations. However, since each section of the rail is very long, the expansion due to heating is significant, and unless space is provided for expansion of rails, the rails will bend to accommodate the increased length. This will make the railway unfit for running of trains.

My Physics teacher taught me this. That's how I know.

Object expand on heating so,answer is c

Simple

Allow for expansion from heat of friction from the train, and from heat during the day. Expressed in the equation V=Beta(V)(Change in Temp.)

The same material expansion occurs with bridges as well.