The figure below shows, at left, a solid disk of radius R = 0.700 m and mass 65.0 kg. T Mounted directly to it and coaxial with it is a pulley with a much smaller mass and a radius of r = 0.230 m. The disk and pulley assembly are on a frictionless axle. A belt is wrapped around the pulley and connected to an electric motor as shown on the right. The turning motor gives the disk and pulley a clockwise angular acceleration of 1.67 rad/s. The tension T in the upper (taut) segment of the belt is 165 N. (a) What is the tension (in N) in the lower (slack) segment of the belt? N (b) What If? You replace the belt with a different one (one slightly longer and looser, but still tight enough that it does not sag). You again turn on the motor so that the disk accelerates clockwise. The upper segment of the belt once again has a tension of 165 N, but now the tension in the lower belt is exactly zero. What is the magnitude of the angular acceleration (in rad/s)? rad/s2