‘Free fall’ produces {HEAD ~ a change} in the force, i.e. acceleration, of gravity as perceived in {TAIL ~ the frame} of reference in which the data storage device is at rest 
as perceived in
‘ Free fall ’ produces { HEAD ~ a change } in the force , i.e. acceleration , of gravity as perceived in { TAIL ~ the frame } of reference in which the data storage device is at rest
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH