If a rigid body is rotating around a fixed axis the tangential and normal components would have to be considered along with the effects of the mass moment. The equations that would be used to solve a problem that has rotation about a fixed axis can be seen below.

**(Eq 1)** $F_n=ma_n$

**(Eq 2) **$F_t=ma_t$

**(Eq 3)** $∑M=Iα$