Chap 13.pdf - Multiparticle Model Unit 13 u2013 Real...

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Multiparticle Model: Unit 13 – Real Fluids and Drag Page 67 of 26 6) A hemispherical parachute made of an air-impervious material is 8.0 m in diameter. The mass of parachute and load combined is 80(kg). (Assume a drag coefficient of 1.42 based on frontal area facing flow and the viscosity of air is 1.8x10 -5 (Pl)) a) How fast will the parachute descend in still air assuming pressure drag dominates? b) How fast will the parachute descend in still air assuming viscous drag dominates? c) Calculate the Reynolds number based on these two calculations and determine whether pressure drag or viscous drag dominates: d) How far would an object with no drag have to fall to reach this same speed as it accelerates from rest? (Landing with a parachute will thus involve about the same impact as would a downward free jump of this distance.) 7) Trees and vines have pipes ("xylem") that convey water upward from roots to leaves. Let us assume that these

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