Figure 9.11 shows

(a) Considering the graph from the question, highlight the part which corresponds to stress @ 150 × 10⁶ N/m²

We can clearly observe that the strain at the stress point 150 × 10⁶ N/m², is 0.002.

By definition, Young’s modulus, Y =

⇒ Y =

⇒ Y = 7.5 × 10¹⁰ N/m²

Hence, Young’s modulus for the given material is 7.5 × 10¹⁰ N/m².

(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 above graph that the approximate yield strength of the material is 300 × 10⁶ Nm^-2.