Thermal expansion....

Question

A rod of length  2m rests on smooth horizontal floor. If the rod is heated from 0° to 20° C . Find longitudinal strain developed.

Ans)Zero

 

I know it has something to do with 'smooth horizontal floor' but i have no idea what. Can someone tell me how to approach this question? 

Answer 1

To answer this question, you need to know the material that the rod is made of, and look up its coefficient of thermal expansion, α.  The longitudinal strain may be calculated using

 

ΔL/L = αΔT,

 

where ΔT is the change in temperature.  In the problem statement you say the answer is zero, but that cannot be right if the temperature of the rod changes.