A semicircular uniform slice has mass m and radius r (a) Please derive the position of its center of mass and the mass moment of inertia (with O as the axis of rotation) (5%) < (b) When the sheet is set as shown in Figure 1, the starting angle is 0=0, release it to make it rotate freely, please deriving the forces Ft and Fn in the direction of its tangent (t-component) and normal (n-component), and express it as 0 (5%) < n Figure 1 1 1 I 0 La @