Why are gaps left in between rails, while laying a railway line? Explain.

Why are gaps left between successive rails on a railway track ?

Small gaps are left between railway lines because :

Why is a small gap left behind the walls while mounting a girder for roofing? Explain.

The gap between any two rails each of length l laid on a railway trach equals x at 27^@C When the temperature rises to 40^@C the gap closes up. The coefficient of linear expansion of the material of the rail is alpha . The length of a rail at 27^@C will be

The pitch of a screw gauge is 1 mm and there are 100 divisions on its circular scale. When nothing is put in between its jaws, the zero of the circular scale lies 6 divisions below the reference line. When a wire a placed between the jaws, 2 linear scale divisions are clearly visible while 62 divisions on circular scale coincide with the reference line. Determine the diameter of the wire.

Statements given below are incorrect. Write the correct statements. Small gaps are provided between the railway lines to provide for easy transportation and laying of railway lines.

A rail track made of steel having length 10 m is clamped on a railway line at its two ends on a summer day due to rise in temperature by 20^@C, it is deformed as shown in fig. Find x (displacement of the centre) if alpha_(steel) = 1.2 xx 10^(-5)//^@C.

Why are electric transmission lines kept slightly loose, when they are laid in summer? Explain.

The pitch of a screw gauge having 50 divisions on its circular scale is 1 mm When the two jaws of the screw gauge are in contact with each other, the zero of the circular scale lies 6 divisions below the line of gradution. when a wire is placed between the jaws, 3 linear scale divisions are clearly visible while 31 division on the circular scale coincides with the reference line. Find diameter of the wire.

The pitch of a screw gauge having 50 divisions on its circular scale is 1 mm When the two jaws of the screw gauge are in contact with each other, the zero of the circular scale lies 6 divisions below the line of gradution. when a wire is placed between the jaws, 3 linear scale divisions are clearly visible while 31 division on the circular scale coincides with the reference line. Find diameter of the wire.