A rigid object is built by welding a thin hoop of mass and radius to a uniform solid…

PHYSICS · Single correct · AP · Physics 1: Algebra-based · Energy and Momentum of Rotating Systems · Energy and Momentum of Rotating Systems

Problem

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\%