Question

For a perfect rigid body the value of Young's modulus will be.

• A. Infinity
• B. Zero
• C. Unity
• D. Finite non-zero value

Answer 1

The correct option is A Infinity

For a rigid body, there is no extension in its length i.e., $\Delta l=0$.
The Young's modulus is given by
$y=\frac{F/A}{\frac{\Delta l}{l}}=\frac{Fl}{A\Delta l}=\frac{Fl}{0}=\infty$
Hence, the Young's modulus for a perfect rigid body will be infinity.