(`a`) A rigid body of radius of gyration `k` and radius `R` rolls without slipping down a plane inclined at an angle `theta` with the horizontal. Calculate its acceleration and the frictional force acting on it.
(`b`) If the body be in the form of a disc and `theta=30^(@)`, what will be the acceleration and the frictional force acting on it.

Explanation

To solve the problem step by step, we will break it down into two parts as given in the question.

### Part (a): Calculate the acceleration and frictional force

1. **Identify the Forces Acting on the Rigid Body**:
- The weight of the body \( mg \) acts vertically downward.
- The component of weight acting parallel to the incline is \( mg \sin \theta \).
- The component of weight acting perpendicular to the incline is \( mg \cos \theta \).
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