A 2-mm-diameter, pure copper wire is reduced to a 1.75-mm diameter by cold working. What is its tensile strength? (See Figure.)

Strength (psi) 100,000 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 Tensile strength Yield strength % Elongation 60 Percent cold work 20 40 80 100 90 80 70 60 50 40 30 20 10 100 % Elongation