Question

what is apsidal angle in central orbit ?

Answer 1

In principle, a circular orbit is a possible orbit for any attractive central force. However, not all forces result in stable circular orbits. Let us now consider the stability of circular orbits in a general central force-field. Equation (250) generalizes to 

Answer 2

Answer :

Central orbit : When a particle moves under any attractive or repulsive force respective to a fixed point, a path is described by the particle in the plane and that path is central orbit.

Apse : On any central orbit described by a particle moving in the plane, a point is found on the orbit whose distance from the centre of force is either maximum or minimum and that point is an apse.

Apsidal distance : The distance of an apse for any central orbit from its centre of force is called apsidal distance.

Apsidal angle : The angle between apsidal distances taken in consecutive pairs is called apsidal angle.