A spring has a force constant of 884 N/m and an unstretched length of 9 cm. One end is attached to a post that is free to rotate in the center of a smooth table, as shown in the top view below. The other end is attached to a 9 kg disk moving in uniform circular motion on the table, which stretches the spring by 2 cm.

What is the centripetal force Fc on the disk?
Answer in units of N