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