Initial angular velocity ω0=1200 rpm=601200×2π=40π rad/s
Final angular velocity ω=0
Time t=10 s
Angular acceleration α=tω−ω0=100−40π=−4π rad/s2
Moment of inertia of the solid sphere I=52MR2=52×5×(0.04)2=0.0032 kg m2
Torque τ=I∣α∣=0.0032×4π=0.0128π Nm
Angle rotated θ=2ω0+ωt=240π+0×10=200π rad
Number of rotations N=2πθ=2π200π=100
Answer: 0.0128π Nm, 100