Theoretical attempt of determining the angular velocity of a spherical disc

Spherical discs are widely used in various agricultural implements for surface tillage. So, for example, there are disc plows, harrows, hillers, where a spherical disc serves as a working body. In disc plows and harrows, a spherical disc is the main working body that acts on the soil. The defining requirement for discs is the reduction of traction resistance, with satisfactory performance of the main purpose of tillage