The words "grounding" and "grinding" are not related in meaning: "grounding" refers to "ground", meaing the surface of the Earth, and "grinding" is a participle

The words "grounding" and "grinding" are not related in meaning: "grounding" refers to "ground", meaing the surface of the Earth, and "grinding" is a participle of "grind". See https://en.wiktionary.org/wiki/ground https://en.wiktionary.org/wiki/ground for details.