A Solid Sphere of Radius R = 5 Cm and Mass

Multiple Choice

A solid sphere of radius r = 5 cm and mass m = 0.2 kg rolls in a groove as shown.The angle, $\theta$ ,between the points of contact with the groove is 120 ^$\circ$ .If the sphere has a linear velocity of 10 mm/s,what is the rotational kinetic energy?

A) 0.8 mJ
B) 1.0 mJ
C) 1.6 mJ
D) 2.0 mJ
E) undetermined.