  A new equation of motion, which is derived previously by imposing Neumann
boundary condition on cosmological perturbation equations (Shenavar 2016 a), is
investigated. By studying the precession of perihelion, it is shown that the
new equation of motion suggests a small, though detectable, correction in
orbits of solar system objects. Then a system of particles is surveyed to have
a better understanding of galactic structures. Also the general form of the
force law is introduced by which the rotation curve and mass discrepancy of
axisymmetric disks of stars are derived. In addition, it is suggested that the
mass discrepancy as a function of centripetal acceleration becomes significant
near a constant acceleration $ 2c_{1}a_{0} $ where $c_{1}$ is the Neumann
constant and $ a_{0} = 6.59 \times 10^{-10} $ $m/s^{2}$ is a fundamental
acceleration. Furthermore, it is shown that a critical surface density equal to
$ \sigma_{0}=a_{0}/G $, in which G is the Newton gravitational constant, has a
significant role in rotation curve and mass discrepancy plots. Also, the
specific form of NFW mass density profile at small radii, $ \rho \propto 1/r $,
is explained too. Finally, the present model will be tested by using a sample
of 39 LSB galaxies for which we will show that the rotation curve fittings are
generally acceptable. The derived mass to light ratios too are found within the
plausible bound except for the galaxy F571-8.

Astrophysics of Galaxies