A uniform disk turns at 2.9 around a frictionless spindle. A nonrotating rod, of the same mass as the disk and length equal to the disk's diameter,...

A uniform disk turns at 2.9 around a frictionless spindle. A nonrotating rod, of the same mass as the disk and length equal to the disk's diameter, is dropped onto the freely spinning disk . They then both turn around the spindle with their centers superposed.