A body moving with initial velocity u accelerates until it attains velocity v within time t. The distance covered is given by which expression?

The body starts from rest, so the initial velocity is $u = 0 \text{ ms}^{-1}$.
The acceleration is $a = 2 \text{ ms}^{-2}$.
The distance travelled is $s = 9 \text{ m}$.
We need to find the final velocity $v$.

The kinematic equation that relates initial velocity ($u$), final velocity ($v$), acceleration ($a$), and displacement ($s$) is:

The magnitude of its velocity after travelling $9 \text{ m}$ is $\boxed{\text{6.0 ms}^{-1}}$.