Passage-III : If the ends of a rod are rigidly clamped so as to prevent any actual expansion or contraction and then the temperature of the rod is changed, the rod will develop tensile or compressive street or thermal stress. This type of stress sometimes could be adequate to cause permanent strain or also break the rod. To avoid damages for the above said reasons concrete highways are always left with gasps between the section for the expansion or contraction of concrete In a similar way, if the temperature of an object under pressure is increased but the object is not allowed to expand, the pressure will also increase. Assuming a negative sign for a compressive stress and positive sign for tensile stress, answer the following questions Again if we consider a rod rigidly clamped at its ends and its temperature is increased or decrease, the thermal stress in the rod can be expressed as (ANSWER)