Question

What will be the modulus of rigidity for water, considering it to be ideal fluid ?

• A. $\infty$
• B. $0$
• C. $1$
• D. $-0.75$

Answer 1

The correct option is B $0$

Ideal fluids can not sustain shear stress, so shear stress $=0$
From the definition of modulus of rigidity:
$\text{Modulus of rigidity}=\frac{\text{Shear stress}}{\text{shear strain}}$
$\therefore \text{Modulus of rigidity}=\frac{0}{\text{shear strain}}=0$