Thermodynamics and Fluid Mechanics Thermodynamics and Fluid Mechanics Physics Help Forum Dec 7th 2009, 02:12 PM #1 Junior Member   Join Date: Dec 2009 Location: MN Posts: 14 problem on volume flow rate A pump is used to empty a 6000 L wading pool. The water exits the 2.5 cm diameter hose at a speed of 2.1 m/s. How long will it take to empty the pool? First thing I did was convert to meters 6000 L = 6 m^3 (I think LOL) 2.5 cm = .025 m First equation I used is Av=Q .025*2.1=.0525 m^2/s The problem is that my book says that Q should be measured in m^3/s which will make sense if I continue but I'm getting m^2/s. What am I dong wrong? A=cross-sectional area of tube v= velocity Q= volume flow rate Next I would use Q=Volume/Time=> Time=volume/Q T=6m^3/.0525m^2/s   Dec 7th 2009, 10:43 PM #2 Physics Team   Join Date: Feb 2009 Posts: 1,425 Firstly Area x vel = (meter x meter) x meter / sec = meter^3 / sec. = vol/sec First find the volume flow rate i.e. how many m^3 leave the pool per sec. Let this be say v . Then divide 6 by v to get the time. I think your problem is that you have not calculated the area which should be pi d^2 / 4 or pi r^2 . You have used only the dia instead.  Tags flow, problem, rate, volume Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post ling233 Advanced Mechanics 0 Apr 27th 2016 06:28 PM ling233 Advanced Mechanics 3 Jan 17th 2016 05:18 AM robhare General Physics 1 Apr 25th 2011 10:20 AM alexito01 Thermodynamics and Fluid Mechanics 3 Mar 11th 2009 08:32 AM Devlan Thermodynamics and Fluid Mechanics 0 Nov 10th 2008 08:48 AM 