NIELIT 2016 MAR Scientist C - Section C: 26

Question

The seek time of a disk is $30$ ms. It rotates at the rate of $30$ rotations/second. The capacity of each track is $300$ words. The access time is (approximately)

• A. $62$ ms
• B. $60$ ms
• C. $50$ ms
• D. $47$ ms

Answer 1

Access time = seek time + rotational latency

if rotational latency is not given we take rotational latency as half the rotation time.

Given, 30 rotation in 1 second => 1 rotation in 1/30 second

so rotational latency = (1/30)*(1/2) = 1/60 second = 1000/60 ms = 16.67 ms

seek time = 30 ms

access time = 30 + 16.67 = 46.67 = 47 ms approximately,

Option (D) is the answer.

Answer 2

option D will be the correct