We are given that the velocity \( \mathbf{v} = 3\hat{i} + 3\hat{j} \). To find the acceleration \( \mathbf{a} \), we need to differentiate the velocity vector with respect to time.
1. Step 1: Understand the relationship between velocity and acceleration
The acceleration is the rate of change of velocity with respect to time:
\[
\mathbf{a} = \frac{d\mathbf{v}}{dt}
\]
2. Step 2: Analyze the velocity
The given velocity vector \( \mathbf{v} = 3\hat{i} + 3\hat{j} \) is a constant vector. This means that both the i-component (3) and the j-component (3) do not change over time.
3. Step 3: Differentiate the velocity
Since the velocity vector is constant, its derivative with respect to time is zero:
\[
\mathbf{a} = \frac{d}{dt}(3\hat{i} + 3\hat{j}) = 0
\]
Therefore, the acceleration \( \mathbf{a} \) is zero.