  Hall effect and magnetoresistance have been measured on single crystals of
the parent phase NaFeAs under a uniaxial pressure. Although significant
difference of the in-plane resistivity $\rho_{xx}(I\parallel a)$ and
$\rho_{xx}(I\parallel b)$ with the uniaxial pressure along $b$-axis was
observed, the transverse resistivity $\rho_{xy}$ shows a surprisingly isotropic
behavior. Detailed analysis reveals that the Hall coefficient $R_\mathrm{H}$
measured in the two orthogonal configurations ($I\parallel a$-axis and
$I\parallel b$-axis) coincide very well and exhibit a deviation from the high
temperature background at around the structural transition temperature
$T_{\mathrm{s}}$. Furthermore, the magnitude of $R_\mathrm{H}$ increases
remarkably below the structural transition temperature. This enhanced Hall
coefficient is accompanied by the non-linear transverse resistivity versus
magnetic field and enhanced magnetoresistance, which can be explained very well
by the two band model with anisotropic mobilities of each band. Our results
together with the two band model analysis clearly show that the anisotropic
in-plane resistivity in the nematic state is closely related to the distinct
quasiparticle mobilities when they are moving parallel or perpendicular to the
direction of the uniaxial pressure.
