Suppose a 1 meter long bar expands 0.5 centimeters when heated. by how much will a 100 meter long bar of the same material expand when similarly heated?

50 cm

Explanation:

Let the increase i  temperature of the metal rod is ΔT and the coefficient of linear expansion of the material of metal rod be ∝.

By use of the formula of linear expansion,

   .... (1)

Let the expansion in length of rod is ΔL.

So,

   .... (2)

Dividing equation (2) by equation (1), we get  

ΔL = 0.5 m = 50 cm