- An electro-optical computer mouse has two choppers mounted at right angles.
- The vestibular system, located inside the human skull behind each ear, consists of three mutually perpendicular, angular acceleration detectors called semicircular canals. The utricle senses motion in the horizontal plane while the saccule senses acceleration in the vertical plane. What's the third? (Alcohol consumption changes the density of the fluids in these canals which leads to the sensation that the room is spinning.)
components in a rotated coordinate system, the inclined plane
conversion between alternate coordinate systems: polar and rectangular.