Question

The platter of the hard drive of a computer rotates at 7600 rpm (rpm = revolutions per minute = rev/min).What is the angular velocity (rad/s) of the platter?If the reading head of the drive is located 3.00 cm from the rotation axis, what is the linear speed of the point on the platter just below it?If a single bit requires 0.50 μm of length along the direction of motion, how many bits per second can the writing head write when it is 3.00 cm from the axis?

Answer 1

a)

$$f=\frac{7600}{60}\frac{rev}{s}$$

$$\omega=2\pi\frac{7600}{60}=796\frac{rad}{s}$$

b)

$$v = rω = (0.03)(754 ) = 22.6 \frac{rad}{s}$$

c)  For each bit

$$s = 0.5\cdot10^{-6} m$$

$$\frac{ 22.6 }{ 0.5\cdot10^{-6} }= 45\cdot10^{6} \frac{bit }{ s }$$