A bar of copper section 8 mm x 8 mm is subjected to an axial pull of 7000N . The lateral dimensions of the bar are found to be changed to 7.9985mmx7.9985mm . If the modulus of rigidity of the material is 0.8 x10⁵ N / mm² Determine the Poisson's ratio and modulus of elasticity [ Hint: E = 2C (1 + u) , where C = modulus of rigidity, E = modulus of elasticity and u = Poisson's ratio ]