Since golf balls behave in a linear viscoelastic fashion, {HEAD ~ inbound ball velocity} is functionally equivalent to {TAIL ~ club swing speed} 
is functionally equivalent to
Since golf balls behave in a linear viscoelastic fashion , { HEAD ~ inbound ball velocity } is functionally equivalent to { TAIL ~ club swing speed }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL