AP PHYSICS 2 SUMMARY CHAPTER 11 - FLUIDS IN MOTION Flow rate The flow rate Q of a fluid is the volume V of fluid that passes a cross section in a tube divided by the time interval 𝚫t needed for that volume to pass. Flow rate also equals the product of the average speed v of the fluid in the cross-sectional area A of the vessel. Continuity equation a fluid does not accumulate the flow rate into a region (position 1) equal the flow rate out of the bridges (position 2). At position 1 the fluid has speed v1 and the tube has cross-sectional area A1. At position to this we would have stayed v2 and the two has crosssectional area A2. Bernoulli’s equation For a fluid flowing without friction or turbulence, the some of the kinetic energy density (½) v2, the gravitational potential energy density g y, and pressure P of the fluid is a constant.