A solid cylindrical disk has a radius of 0.25 m and it can rotate about a vertical axis.
a. When a 45 N force is applied tangentially to the disk, perpendicular to the radius, the disk acquires an angular acceleratrion of 80 rad/s^2. What is the mass of the disk?
b. A small 0.2 kg mass is now welded at the edge of the disk. If the same force as in Part A is now applied to the disk, what is its new angular accelaeration?