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Unformatted text preview: ECM 5 Winter, 2009 Solution Set 6 Given the definition of the Reynolds number: (1) μ ρ vd N = Re 1. a) For the SI system of units, determine the units of each of the variables in the Reynolds number. Solution : The SI units for length (L), time (T), and mass (M) are meters (m), seconds (s), and kilograms (kg), respectively. Thus, looking at the base units for each variable in the Reynolds number, we substitute their SI units. 3 3 m kg L M density = = = ρ characteristic velocity s m T L v = = = characteristic length m L d = = = s m kg T ML ity vis ⋅ = = = μ cos 1. b) What are the units of N Re ? Solution : We determine the units of NRe from dimensional analysis. That is, we substitute variables in the equation with their units (making sure that all units are of the same system and magnitude) and examine for cancellations and simplifications. [ ] [ ] 1 3 2 3 Re = ⋅ ⋅ = ⋅ ⋅ ⋅ = ...
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- Fall '09
- International System of Units, Kilogram