a copper alloy is found to have a yield strength of 240 MPa , a tensile strength of 310 MPa and an elastic modulus of 110 GPa. A cylindrical specimen of this alloy 18 mm in diameter and 400 mm long is stressed in compression and found to shorten by 3.0 mm a) calculate the operational compressive strain this copper specimen is subjected to. b) calculate the maximum strain this copper alloy can sustain without becoming plastically deformed.