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