The long term evolution of the relative rotation of the core super fluid in a neutronrnstare with respect to the rest of the star is determined through Legase modal.The corernsuperfluid rotates at a different rate ,while spinning down at the same steady-state rate asrnthe rest of the star, because of the assumed pinning between the superfluid vortices andrnthe superconductor fluxoids.We find that the magnitude of this rotational lag changes withrntime and also depends on the distance from the rotation axis; the core superfluid supportsrnan evolving pattern of differential rotation. We argue that the predicted change of the lagrnmight occur as discrete events which could result in a sudden rise of the spin frequency ofrnthe crust of a neutron star, as is observed at glitches in radio pulsars. This new possibilityrnfor the triggering cause of glitches in radio pulsars is further supported by an estimaternof the total predicted excess angular momentum reservoir of the core superfluid. Thernmodel seems also to offer resolutions for some other aspects of the observational data onrnglitches. The goal of this project is to show the tidal effect on the differential motion ofrnthe crust with respect to the core of the neutron star from that we find the redistributionrnof angular velocity and tidal locking time for the crust core interaction of neutron stare