Young's modulus for a perfectly rigid body is

Explanation

To determine the Young's modulus for a perfectly rigid body, we can follow these steps:

### Step 1: Understand the Definition of Young's Modulus
Young's modulus (Y) is defined as the ratio of tensile stress to longitudinal strain. Mathematically, it can be expressed as:
\[ Y = \frac{\text{Tensile Stress}}{\text{Longitudinal Strain}} \]

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