F=r(⑦ In Cartesian coordinate system F =x(t)i +y(t)j+z(t)k In component form x =x(t) y=y() z=z(t) r x t i y t j z t k      ( )  ( )  ( ) r r(t)    In Cartesian coordinate system In component form ( ) ( ) ( ) z z t y y t x x t    x o z y r 