Ncert Exercises & Solutions

Q.14 The Young's modulus for steel is much more than that for rubber. For the same longitudinal strain, which one will have greater tensile stress?

Hint: The stress in the material depends on Young's modulus of the material.

Step 1: Find the tensile stress in the two materials.

Young's modulus (Y) =

\frac{Stress}{Longitudinal strain}

For the same longitudinal strain,

Y \propto Stress

∴ \frac{Y_{Steel}}{Y_{rubber}} = \frac{{(Stress)}_{steel}}{{(stress)}_{rubber}} . . . (i)

But

Y_{steel} > Y_{rubber}

∴

\frac{Y_{steel}}{Y_{rubber}} > 1

Therefore, from Eq. (i),

\frac{{(stress)}_{steel}}{{(stress)}_{rubber}} > 1

\Rightarrow

{(stress)}_{steel} > {(stress)}_{rubber}