Question

Figure shows the stress-strain graphs for materials $A$ and $B$. From the graph, it follows that

• A. Material $A$ has a higher Young's modulus.
• B. Material $B$ is more ductile.
• C. Material $B$ can withstand greater stress.
• D. Material $A$ can withstand greater stress.

Answer 1

Answer: (A), (D)

Material $A$ can withstand greater stress.

The slope of the linear portion (elastic limit of the material) of the curve gives the Young's modulus $\left(Y\right)$ of the material.
Here, in the elastic limit,
$(\text{Slope}{)}_A>(\text{Slope}{)}_B$
Hence, material $A$ has higher $Y$.
Statement $\left(a\right)$ is correct.

The plastic region for material $A$ (region $PQ$) is greater than that for material $B$ ( region $RS$), which indicates that material $A$ is more ductile.
Hence, statement $\left(b\right)$ is incorrect.

The breaking stress for material $B$ (i.e., stress corresponding to the end point of curve) is less than breaking stress for material $A$.Thus, material $B$ will sustain a lower stress compared to material $A$ before breaking, hence it is more brittle.
Hence, choice $\left(c\right)$ is also incorrect.

Material $A$ is stronger than material $B$ because it can withstand a higher stress before it breaks.
Hence, the correct choices are $\left(a\right)$ and $\left(d\right)$.