A rod of length 50 cm and area of cross section 4 mm2 is pulled at both ends by force of magnitude 100 N. The longitudinal stress in the rod is
A brass rod of length 2 m and cross-sectional area 2 cm2 is attached end to end to a steel rod of length L and cross-sectional area 1 cm2. The compound rod is subjected to equal and opposite pulls of magnitude 5×104 N at its ends. If the elongations of the two rods are equal, then the length (in m) the steel rod(L) is___
[YB=1×1011 N/m2 and YS=2×1011 N/m2]