A wheel undergoes three consecutive 2.0 s intervals:
• Interval I: its angular momentum increases from 0 to 6 kg·m²/s.
• Interval II: its angular momentum remains constant at 6 kg·m²/s.
• Interval III: its angular momentum decreases from 6 kg·m²/s to −6 kg·m²/s.
Rank the magnitude of the net external torque during the three intervals from greatest to least and state the sign (positive, zero, or negative) of the torque in each interval.