### Q.2:- Figure 9.11 shows the strain-stress curve for a given material. What are (a) Young’s modulus and (b) approximate yield strength for this material?

**Answer:-**(a) It is clear from the given graph that for stress 150 × 10^{6} N/m^{2}, strain is 0.002.

∴Young’s modulus, *Y* = Stress / Strain

= 150 × 10^{6} / 0.002 = 7.5 × 10^{10} Nm^{-2}

Hence, Young’s modulus for the given material is 7.5 ×10^{10} N/m^{2}.

(b) The yield strength of a material is the maximum stress that the material can sustain without crossing the elastic limit.

It is clear from the given graph that the approximate yield strength of this material is 300 × 10^{6} Nm/^{2} or 3 × 10^{8} N/m^{2}.