As a result of friction, the angular speed of a wheel c hanges with time according to d θ d t = ω0 e −σ t , where ω0 and σ are constants. The angular speed changes from an initial angular speed of 2.88 rad/s to 1.38 rad/s in 3.92 s. (a) Determine the magnitude of the angular acceleration after 1.88 s. Answer in units of rad/s 2 . (b) How many revolutions does the wheel make after 2.6 s ? Answer in units of rev. (c) Find the number of revolutions it makes before coming to rest.