A railway is laid so that there is no stress in rail at 10

Question

A railway is laid so that there is no stress in rail at 10º C. If rails are 30 m long Calculate,

1. The stress in rails at 60º C if there is no allowance for expansion.

2. The stress in the rails at 60º C if there is an expansion allowance of 10 mm per rail.

3. The expansion allowance if the stress in the rail is to be zero when temperature is 60º C.

4. The maximum temp. to have no stress in the rails if the expansion allowance is 13 mm/rail.

Take a = 12 x 10 ^-6 per 1ºC         E= 2 x 10 ⁵ N/mm ²