A 4.0 m long copper wire of cross sectional area 1.2 cm2 is stretched by a force of 4.8×103 N. The stress will be
An 8m long copper wire and a 4m long steel wire, each of cross-section 0.5 cm2 are fastened end to end and stretched by a 500 N force. The elastic potential energy of the system is (YCopper=1×1011Nm−2;Ysteel=2×1011Nm−2)