For a magnetic disk with concentric circular tracks, the seek latency is not…

Correct answer: arm starting or stopping inertia

Explanation: The physical motion of the actuator arm causes seek time to depend on acceleration and deceleration phases rather than being a simple linear function of distance.

• Motion profile: a typical seek consists of acceleration from rest, possibly a constant-velocity cruise phase, and deceleration to stop.

• Short seeks: the arm may not reach maximum velocity, so most of the time is spent accelerating and decelerating; time grows sub-linearly with distance.

• Long seeks: after acceleration the arm can cruise at top speed for a while, adding a distance-proportional component, so different distance ranges show different time behavior.

• Fixed overheads such as settling, overshoot correction, and servo control introduce additional time components that are not proportional to distance.

Implication: Because of the acceleration/deceleration behavior and fixed overheads, simple linear models are inaccurate; seek-time models often include constant terms and different scaling for small and large moves.

Why the other choices are not correct:

• Non-uniform request distribution affects average observed seek distances, but it does not change the physical time-vs-distance relationship for an individual seek.

• Higher track capacity at the periphery affects data density and transfer rate, not mechanical seek dynamics.

• Uniform scheduling policies influence request ordering and average latency but do not change the actuator's physical acceleration/deceleration behavior.