Question

The radius of the magnetic disk in a 3.5-inch
diskette is 1.68 in. Find the linear speed of a
point on the circumference of the disk if it is
rotating at a speed of 350 rev/min.
Answer in units of in/sec

Answer 1

you need to convert rev/min to radians per second
this is the angular velocity
then you need to use the formula relating linear speed to angular velocity

Answer 2

this is v=wr where w = angular velocity and r = radius

Answer 3

We're looking at the speed of a point (let's pretend its a piece of dust) right on the edge of a spinning disk. Every revolution, the point will travel a distance pi*D, the circumference of the disk. Multiply this by revolutions per minute, and you get the speed of the dust particle. Don't forget to convert minutes to seconds

v = pi*D*rpm
= pi*(1.68 in*2)*350 rev/min * 1min/60second
= 61.6 in/sec