Any acceleration towards the centre is related to the velocity and radius:

Obviously this is a scalar equation – it doesn’t give direction as both and are constantly changing (so is for that matter). We also cannot divide vectors (we may be able to square them).

N
v r This means that the outer parts of a hard drive are accessed faster. The outer partitions are fastest!

ow for a circle, the distance around it is 2r and the time for one revolution is T.
v = 2r/T or 2rf. This means that our formula for acceleration can be written as