A Newtonian fluid of viscosity $\mu$ flows between two parallel plates due to the motion of the bottom plate (as shown below), which is moved with a velocity $V$. The top plate is stationary.

The steady, laminar velocity profile in the $x$ -direction is

1. $V[\frac{y}{b}]$
2. $V[(\frac{y}{b})^{2}-1]$
3. $V[1 -(\frac{y}{b})^{2}$]
4. $V[1 -\frac{y}{b}$]