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Problem 1.7 [Difficulty: 3] Given: Small particle accelerating from rest in a fluid. Net weight is W, resisting force F D = kV, where V is speed. Find: Time required to reach 95 percent of terminal speed, V t . Solution: Consider the particle to be a system. Apply Newton's second law. Basic equation: ∑ F y = ma y Assumptions: 1. W is net weight 2. Resisting force acts opposite to V Then F yy ∑ =− = = Wk V =m a dt m dV W g dV dt or dV dt g(1 k W V) Separating variables, dV 1V
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This note was uploaded on 10/19/2011 for the course EGN 3353C taught by Professor Lear during the Fall '07 term at University of Florida.
- Fall '07
- Fluid Mechanics