A turbine fan in a jet engine has a moment of inertia of 2.5 kg x m^2 about its axis of rotation. As the turbine starts up, its angular velocity is given by wz = (40 rad/s^3)t^2. (a) Find the fan's angular momentum as a function of time, and find its value at t = 3.0 s. (b) Find the net torque on the fan as a function of time, and find its value at t = 3.0 s.