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