If `|vec(a)|=3`, what is :
`|0vec(a)|` ?

Answer

To solve the problem, we need to find the value of \( |0 \vec{a}| \) given that \( |\vec{a}| = 3 \).

### Step-by-Step Solution:

1. **Understanding the Problem**:
- We are given the magnitude of vector \( \vec{a} \) as \( |\vec{a}| = 3 \).
- We need to find the magnitude of the vector \( 0 \vec{a} \).

2. **Scalar Multiplication**:
- The expression \( 0 \vec{a} \) represents the vector \( \vec{a} \) multiplied by the scalar \( 0 \).
- When any vector is multiplied by \( 0 \), the result is the zero vector, denoted as \( \vec{0} \).

3. **Magnitude of the Zero Vector**:
- The magnitude of the zero vector \( \vec{0} \) is always \( 0 \).
- Therefore, we can write:
\[ |0 \vec{a}| = |\vec{0}| = 0 \]

4. **Final Answer**:
- Thus, the value of \( |0 \vec{a}| \) is \( 0 \).

### Conclusion:
The final answer is:
\[ |0 \vec{a}| = 0 \]