A ceiling fan is mounted so that its axis is vertical. Anticlockwise rotation viewed from below is taken as the positive sense according to the usual right-hand rule. The fan starts from rest and reaches an angular speed of 120 rpm in 10 s with uniform angular acceleration.
(i) State, with sign, the angular velocity of the fan at t=10s in SI units.
(ii) What is the sign of the angular acceleration during the start-up? Give a brief reason.
(iii) Would the angular displacement of the fan during the 10 s interval be positive, negative or zero? Justify your answer without performing any numerical calculation.