  By carefully analyzing the geodesic motion of a test particle in the bulk of
brane worlds, we identify an extra force which is recognized in spacetime of
one lower dimensions as a non-gravitational force acting on the particle. Such
extra force acts on the particle in such a way that the conventional particle
mechanics in one lower dimensions is violated, thereby hinting at the
higher-dimensional origin of embedded spacetime in the brane world scenario. We
obtain the explicit equations describing the motion of the bulk test particle
as observed in one lower dimensions for general gravitating configurations in
brane worlds and identify the extra non-gravitational force acting on the
particle measured in one lower dimensions.
