A copper wire of diameter 0.30mm and length 1.50m is joined to another steel wire of same diameter and length 1.20m. The copper part of the double wire is hung vertically to a fixed point, while a small weight is connected to the lower end of the steel part. Joining the two wires tighter has lead to compression of each one of them by 20mm. Later a 30N weight is connected to the lower point of the steel part. Calculate:

Question

A copper wire of diameter 0.30mm and length 1.50m is joined to another steel wire of same diameter and length 1.20m. The copper part of the double wire is hung vertically to a fixed point, while a small weight is connected to the lower end of the steel part. Joining the two wires tighter has lead to compression of each one of them by 20mm. Later a 30N weight is connected to the lower point of the steel part. Calculate:
a.The stress in each wire
b.The strain of each wire, knowing that Young modulus of copper is 1.3 x 10^11 N/m^2 and of steel is 2.0 x 10^11 N/m^2
c.The total elongation of both wires