41) A steel rod of 1 m length has to transmit a force of 15 kN without stretching more than 1mm. E of steel is 200Gpa. Minimum cross sectional area required is

42) A thin cylindrical shell of diameter (d), length (l), and thickness (t) is subjected to an internal pressure (p). The ratio of the longitudinal strain to hoop strain is

43) Rankine's constant for a mild steel column with both ends hinged is

44) The material used in the manufacture of thermistors are

45) A metal strip is to be rolled from initial wrought thickness of 3.5 mm to a final rolled thickness of 2.5 mm in a single pass rolling mill having rolls of 250 mm diameter. The strip is 450 mm wide. The average co-efficient of friction in the roll gap is 0.