Ncert Exercises & Solutions

Q. 17 What is the Young's modulus for a perfect rigid body.

Hint: In a perfect rigid body, the distance between any two points does not change.

Step 1: Find the Young's modulus of a perfect rigid body.

Young's modulus (Y) =

\frac{F}{A} \times \frac{l}{∆ l}

For a perfectly rigid body, the change in length,

∆ l = 0

∴ Y = \frac{F}{A} \times \frac{l}{0} = \infty

Therefore, Young's modulus for a perfectly rigid body is infinite

(\infty)