A rigid object is built by welding a thin hoop of mass m and radius R to a uniform solid disk of mass m and the same radius so that their centers coincide. The combined object rolls without slipping on a horizontal surface with translational speed v. Which of the following is closest to the percentage of the object’s total kinetic energy that is rotational?
a) 29%
b) 71%
c) 43%
d) 57%