Just stumbled on this video from the Slow Mo Guys on YouTube and loved it. These guys took a computer hard drive apart and let us see inside while it was spinning. Remember, most hard drives spin at 7200 revolutions per minute (rpm). In the video you see a little arm going back and forth. This little arm has a read/write head on the end of it. This head is what reads and write the data to the spinning disk. Hard to believe isn’t it. So, whenever you use your computer, your hard disk is spinning at 7200 rpm and this little arm is flicking back and forth reading and writing data. Amazing!
Warning: in the video they were joking about hard drives working if you pour water on them. Do NOT do this! It will destroy your hard drive and all your data!