A hollow spherical shell with mass 1.65 kg rolls without slipping down a slope that makes an angle of 30.0 degrees with the horizontal.

A. Find the magnitude of the acceleration a_cm of the center of mass of the spherical shell. Take the free-fall acceleration to be g = 9.80 m/s² .

B. Find the magnitude of the frictional force acting on the spherical shell. Take the free-fall acceleration to be g = 9.80 m/s² .

C. Find the minimum coefficient of friction needed to prevent the spherical shell from slipping as it rolls down the slope.