how does a harddisk work? block / sector
This is something that has changed over the decades.

In the past, the blocks were laid out exactly as you see in the picture.  The bit density of the outer blocks was less than those of the inner blocks.  This made the hardware easy to build at the expense of being less efficient.

In modern times, we no longer need to make the hardware easy.  We're interested in maximum efficiency of the harddrive.  Modern harddrives do not have nice easy angular wedges like the old ones do. They, instead, try to keep the bit density as even as possible (maximized at all places).