‘{TAIL ~ 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 rest 
‘ { TAIL ~ 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 rest
OTH TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH