*First of all, what is the volume of said mountain in the calc?
- Second of all, how much energy is required to destroy said mountain in the calc?
Note that when you exceed the amount of energy that is required in order to break the said mountain (via fragmentation, pulverization), the mountain will be destroyed regardless of the kinetic energy that is generated from its freefall.
Thus, 36 Ren x30 energy should only be as powerful as the energy required to destroy the mountain, and slightly more.