Answer Happy

The hard disk setup shown in Figure QB1 consists of a disk of radius R = 5 cm that can rotate at 3000 rpm. The head of the hard disk is a microscale object that offers precise read/write capability, and is manipulated by an arm that controls the radial position from the centre of the disk. The arm also ensures that the leading edge of the head is always pointing perpendicular to the radius of the disk as shown in the figure. Given: Disk-Head: 0 = 15°; h = 0.5x105 m (at x = 0); L = 1x10 m; b = 1x105 m Fluid in gap: air at room temperature a) Determine the total force on the hard disk head when the head is located at radius r = 3/4 R. State clearly any assumptions made. (17) b) Briefly discuss what you would do to improve your prediction. (3) L ROTATING DISK Loading Edge (LE) read/write head R read/write head h 2 disk 0 U db a arm SIDE VIEW TOP VIEW Figure QB1: Schematic of hard disk setup