If you enjoy these exercises, and know of others that may enjoy them as well, then please let them know by visiting the Tell A Friend page. This is Metrology Metro's thirteenth quiz posting. Once MM gathers and analyzes pertinent response data statistics, then the exercises will be tailored accordingly. Units are defined in terms of physical standards.
Standards come in many sizes and shapes, and some are better than others.
Although compound units themselves have no primary standards, the units that compose them do. The SI unit for speed, for instance, is the metre per second . There is one primary standard for the metre, and another one for the second. Used together, they give us the standard for the metre per second. So no matter what measurement we make, we are always indirectly working our way back to comparisons with the primary SI standards.