Why is accessing a disk block expensive? discuss the time components involved in accessing a disk block. (?

Explanation:

A disk block works by transferring data between the disk and main memory units which are called the blocks, whose size can range drastically from 512 bytes to several thousand.  This data is converted to hardware-level cylinder, surface, and sector number  which makes accessing the data immensely slower than accessing data in the main memory. This time constraint is also the main reason as to why accessing a disk block is so expensive.