Consider a laminar flow at zero incidence over a flat plate. The shear stress at the wall is denoted by $\tau _{w}$. The axial positions $x_{1}$ and $x_{2}$ on the plate are measured from the leading edge in the direction of flow. If $x_{2} > x_{1}$, then.
- $\tau _{w}\mid _{x_{1}}=\tau _{w}\mid _{x_{2}}=0$
- $\tau _{w}\mid _{x_{1}}=\tau _{w}\mid _{x_{2}}\neq 0$
- $\tau _{w}\mid _{x_{1}} > \tau _{w}\mid _{x_{2}}$
- $\tau _{w}\mid _{x_{1}} < \tau _{w}\mid _{x_{2}}$