Calculate Pressure Gauge Reading in Wide Section of Pipe

[brunettegurl]

Homework Statement

Water flows at 3.64 L/s through a horizontal pipe that narrows smoothly from 10.2 cm diameter to 4.89 cm diameter. A pressure gauge in the narrow section reads 47.0 kPa. What is the reading of a pressure gauge in the wide section?

Homework Equations

F=PA

P1+ $$\rho$$gh+0.5*$$\rho$$V²=P2+$$\rho$$gh+o.5*$$\rho$$V²

The Attempt at a Solution

so first thing i did was convert 3.64L/s to 3.64x10^-3 m³/s
and then found the area of each part of the opening. since they tell me the gauge reading at the narrow end (4.89cm) i used F=PA to find the force. using this force and the area of the wide end (10.2cm) i got a P. this was wrong..can someone tell me what I'm doing wrong??

 

[tiny-tim]

Hi brunettegurl!

(have a rho: ρ )

I'm confused … what does force have to do with it?

Use conservation of mass to find the speeds, and then use Bernoulli's equation

 

[brunettegurl]

thanks i realized that after i redid what i did