Blu-Ray players like Cd\'s and DVDs use a technique called CLV (Constant Linear
ID: 1783441 • Letter: B
Question
Blu-Ray players like Cd's and DVDs use a technique called CLV (Constant Linear Velocity) to get the same data rate from inner tracks as from the outer ones. They adjust the rotation speed of the disk so that at the place the head is reading the disk surface moves past at a constant speed. You are designing the next generation Purple Ray Player for which the linear speed will be 15 m/s. (For comparison Audio CD's are about 1.2 m/s and Blu-ray about 7 m/s) The new medium will be the same 12 cm diameter as the old. Calculate the needed rotation rate when reading at various locations in both rad/s and rpm.
(a) Reading at its outer edge
(b) Reading at a point 2.45 cm from the center
Explanation / Answer
rotation rate is nothing but angular velocity w
relation between angular speed and linear speed is
v = R*w
15 = (0.12/2)*w
15 = 0.6*w
w = 15/0.6 = 25 rad/s
w = 25*(60/(2*3.142)) = 238.7 rpm
b)angular speed at any point is same
hence at 2.45 cm from the center
w = 25 rad/s = 238.7 rpm