When a body is under pure rolling, the fraction of its total kinetic energy which is the purely rotational is 2/5. Identify the body.

Explanation

To solve the problem, we need to identify the body based on the given information about its kinetic energy during pure rolling. Here's a step-by-step breakdown of the solution:

### Step 1: Understand the Total Kinetic Energy
The total kinetic energy (K.E.) of a rolling body is the sum of its translational kinetic energy and rotational kinetic energy. The formulas for these are:
- Translational K.E. = \( \frac{1}{2} m v_{\text{cm}}^2 \)
- Rotational K.E. = \( \frac{1}{2} I \omega^2 \)

### Step 2: Set Up the Equation
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