ZdzisĹ‚aw Pluta, Tadeusz Hryniewicz, Critics of Existent Theory of Mathematical Pendulum Part 2, ILCPA Volume 13, International Letters of Chemistry, Physics and Astronomy (Volume 13) https://www.scipress.com/ILCPA.13.195 Abstract: In the second part of the paper, the thesis is proved to state that the existent theory describes simply a shadow of the rotating apparent mathematical pendulum. Hence, it appears, even that existent description is not sufficiently adequate. Finally, all defects of the theory, which resulted in so inadequate description of the oscillation motion of the simple mathematical pendulum, have been revealed. The necessity to re-build the existent theory has been indicated in the conclusion. Return to the source is to be the first, essential step on the new path of the cognitive action. Keywords: Amplitude, Angular Velocity, Force of Gravity, Force of Inertia, Mathematical Pendulum, Vibration Period