Physics
posted by lupe .
Water flows at 12 m/s in a horizontal pipe with a pressure of 3.0 x 10 4 N/m2 . If the pipe widens to twice its original radius, what is the pressure in the wider section?

The water speed will drop by a factor 1/4 because of the larger pipe area. That follows from the incompressible fluid continuity equation, V * Area = constant. The water speed in the wider section is 3 m/s
Use the change in velocity and the Bernoulli equation to get the change in pressure.
P + (1/2)(density) V^2 = constant
P2  P1 = (1/2)(water density)(V1^2  V2^2
Solve for P2. 
xas