(清华大学2006--2007学年春季学期期中考试试题)A football,meant to be thrown at 60 mi/h in se
(清华大学2006--2007学年春季学期期中考试试题)A football,meant to be thrown at 60 mi/h in sea--level air(ρ=1.22 kg/m3,μ=1.78E-5 N s/m2)is to be tested using a one—quarter(1/4)scale model in a water tunnel(ρ=998 kg/m3,μ=0.0010 N s/m2).For dynamic similarity,what is the ratio of prototype force to model force?