English: the curvature of the Earth is negligible at this scale, and the gravity force lines can be approximated as being parallel and pointing straight down to the center of the Earth.
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the
same or compatible license as the original.