Water flows throgh a horizontal tube of diameter 2.8cm that is joined to a second horizontal tube of diameter 1.6cm. the pressure difference between the tubes is 7.5kPa. which tube has the higher pressure flow? which tube has the higher speed flow? find the speed of flow in the first tube. P2=p1+ (1/2)density(rho)(v1^2-v2^2) how can i solve with out a velocity 1 or 2?