The degree of freedom of a stationary rigid body about its axis will be :

Options

A. one
B. two
C. three
D. four

Explanation

To determine the degree of freedom of a stationary rigid body about its axis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concept of Degree of Freedom**:
- The degree of freedom refers to the number of independent ways in which a system can move. For a rigid body, this includes both translational and rotational motions.

2. **Identifying the Type of Motion**:
- A stationary rigid body means that it does not translate (move linearly) in space. Therefore, its translational degrees of freedom are zero.

3. **Translational Motion**:
- Since the body is stationary, it cannot move along the x, y, or z axes. Thus, the translational degrees of freedom are:
\[ \text{Translational Degrees of Freedom} = 0 \]

4. **Rotational Motion**:
- A rigid body can rotate about its axes. For a rigid body, there are three axes of rotation (x, y, and z). Therefore, the rotational degrees of freedom are:
\[ \text{Rotational Degrees of Freedom} = 3 \]

5. **Calculating Total Degrees of Freedom**:
- The total degree of freedom for the stationary rigid body can be calculated by adding the translational and rotational degrees of freedom:
\[ \text{Total Degrees of Freedom} = \text{Translational Degrees of Freedom} + \text{Rotational Degrees of Freedom} \]
\[ \text{Total Degrees of Freedom} = 0 + 3 = 3 \]

6. **Conclusion**:
- Therefore, the degree of freedom of a stationary rigid body about its axis is **3**.

### Summary:
The degree of freedom of a stationary rigid body about its axis is **3**.

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