Problem 6 The device shown consists of a disk that is rotated by a shaft. The disk is positioned very close to a solid bound- ary. Between the disk and the boundary is viscous oil. a. If the disk is rotated at a rate of 1 rad/s, what will be the ratio of the shear stress in the oil at r = 2 cm to the shear stress at r = 3 cm? b. If the rate of rotation is 2 rad/s, what is the speed of the oil in contact with the disk at r = 3 cm? c. If the oil viscosity is 0.01 N s/m² and the spacing y is 2 mm, what is the shear stress for the conditions noted in part (b)? What torque is required to rotate the disk at a rate of 5 rad/s, with D = 10 cm and with the same viscosity and spacing as in part (c)? Oil D Disk