Question

Select the correct statement from the following:

• A. Shear modulus of an ideal liquid is infinite
• B. Rubber is more elastic than steel
• C. The bulk modulus of a perfect rigid body is infinite
• D. The bulk modulus of an ideal liquid is zero

Hint:

Rigid body: infinite bulk modulus. Ideal liquid: zero shear modulus. Higher modulus means more elasticity.

Answer 1

The Correct Option is C

Step 1: Understand shear modulus.
Shear modulus measures resistance to change in shape. An ideal liquid cannot sustain shear stress, so its shear modulus is zero, not infinite. Hence option (A) is incorrect.

Step 2: Analyze elasticity comparison.
Elasticity is defined by the ability to regain original shape. Steel has a higher Young’s modulus than rubber, so steel is more elastic. Hence option (B) is incorrect.

Step 3: Understand bulk modulus.
Bulk modulus measures resistance to change in volume. A perfectly rigid body does not change its volume under any pressure.
\[ K = \frac{\Delta P}{\frac{\Delta V}{V}} \]
Since \(\Delta V = 0\), bulk modulus becomes infinite.

Step 4: Analyze option (C).
This matches the definition of a perfectly rigid body, so it is correct.

Step 5: Analyze option (D).
Liquids have finite bulk modulus (they are slightly compressible), not zero. Hence incorrect.

Step 6: Concept clarity.
Rigid body \(\Rightarrow\) infinite bulk modulus, ideal liquid \(\Rightarrow\) zero shear modulus.

Step 7: Final answer.
\[ \boxed{\text{The bulk modulus of a perfect rigid body is infinite}} \]