A simply supported beam AB of span L is subjected to a concentrated load W at the centre C of the span. According to Mohr's moment area method, which one of the following gives the deflection under the load ?
A 600 mm long and 50 mm diameter rod of steel (E = 200 GPa, α = 12 x 10-6/°C) is attached at the ends to unyielding supports. When the temperature is 30°C there is no stress in the rod. After the temperature of the rod drops to - 20°C, the axial stress in the rod will be