A szabadon eso vakumcso nem erzi a gravitaciot (ezert is sulytalan). Reszletesebben lasd:

http://www.physics.ucla.edu/demoweb/demomanual/mechanics/gravitational_acceleration/local_inertial_frame.html

http://en.wikipedia.org/wiki/Inertial_frame_of_reference#Separating_non-inertial_from_inertial_reference_frames

http://www.physlink.com/education/askexperts/ae13.cfm