I person 2 tangent wheels pinned astatine their centers /which coincide pinch nan halfway of mass/ and torque is applied to 1 of them (both rotation without slipping). I want to find what unit would they exert connected a portion of insubstantial passed betwixt them (assuming it tin pass). I did nan FBD for nan instrumentality pinch nan applied torque: I presume nan angular acceleration of nan instrumentality and nan acceleration astatine its halfway to beryllium 0. Then applying $\sum M_A = I_A \cdot \alpha_A$ yields $\ F_f = \frac{M}{r}$, wherever r is nan radius of nan wheel. However I person nary thought whether I should repetition fundamentally nan aforesaid process pinch nan different wheel, which would consequence successful nan portion of insubstantial experiencing a unit pinch magnitude of $\ 2F_f $ successful nan other direciton of $\ 2F_f $.