4. A solid disk has a radius of 1.20 m a mass of 4.00 kg. It is initially rotating with a constant angular speed of 20.0s-1. (a) [5] What constant

angular acceleration will increase the wheel's angular speed to100 s-1 in 4.00 s? Give a numerical answer. (b) [10] What is the magnitude of the linear acceleration of a point on the rim of the wheel when the wheel is half-way towards reaching its final angular speed of100 s-1? Give a numerical answer.