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Spartan301
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Homework Statement
A computer hard drive disk with a diameter of 3.5 inches rotates at 7200 rpm. The “read head” is positioned exactly halfway from the axis of rotation to the outer edge of the disk. What is the tangential speed in m/s of a point on the disk under the read head?
Objective: Find tangential velocity on disk.
Homework Equations
Battle plan:
Convert inches to meters
Find the distance to the axis
Find the angular velocity by dividing the angular displacement by the time.
Convert from an angular speed in rad/s to a tangential speed in m/s by multiplying the angular speed by the radius of rotation.
The Attempt at a Solution
Outcome:
0.0889m/4 = 0.022225 m
7200r/min x 60 = 432000 r/s
432000 r/s x 0.022225 m = 9601.2 m/s :(
The key says the answer is 17 m/s.
I would so appreciate any help on this problem. Thanks!
-Tom