Disk A rotates in a horizontal plane about a vertical axis at the constant rate of 0

Question:

Disk A rotates in a horizontal plane about a vertical axis at the constant rate of θ0 =15 rad/s. Slider B has a mass of 230 g and moves in a frictionless slot cut in the disk. The slider is attached to a spring of constant k = 60 N/m, which is undeformed when r = 0. Knowing that at a given instant the acceleration of the slider relative to the disk is r = ??12 m/s2 and that the horizontal force exerted on the slider by the disk is 9 N, determine at that instant (a) The distance r, (b) The radial component of the velocity of the slider.