11. A solid, cylindrical shaft must withstand 15 kN·m of torque and can only experience 30 MPa of shear stress. What is the minimum radius shaft that can be used?
A) 0.057 mm
B) 4.8 cm
C) 6.5 cm
D) 6.5 m
12. A solid, cylindrical shaft must withstand 32 kN·m of torque and can only experience 285 MPa of shear stress. What is the minimum radius shaft that can be used?
A) 6.6 cm
B) 8.1 m
C) 3.8 cm
D) 23 mm
15. A hollow sphere of mass 8.20 kg and diameter of 20.0 m is spun 4.00 m away from the centroid. What's the moment of inertia, as it spins, off center?
A) 546.67 kg·m^2
B) 677.87 kg·m^2
C) 2317.87 kg·m^2
D) 328.00 kg·m^2