The reaction force is being measured at the stone's fixed support BC.
Yes. Initial rotational velocity is given as 3200 rpm.
Meanwhile, I had finished the analysis with 0 mm, 0.02 mm, 0.04 mm, 0.06 mm gaps too. The variation is of the order as 1513 N, 1569 N, 1807 N, 1469 N respectively. The gap seems to be varying the result without any particular order.
Attached the image of the system for reference.