04/10/2023

MET 212Fluid Mechanics

Lecture # 4

Objective

Pressure Variation in Fluid at Rest Pressure Measurement

Mechanical Pressure Measuring Device

Hydrostatic Force on Plane Surface

04/10/2023

04/10/2023

Pressure Variation in Fluid at Rest

The pressure is the same at tall points along the line AB even with irregular shape

A

h

p=po

B

γ = specific weight

04/10/2023

Pressure Measurement

Representation of gage and absolute pressure

04/10/2023

Pressure Measurement

Mechanical Pressure Measuring Device

Pressure Gauge

04/10/2023

Hydrostatic Force on Plane Surface

FRh

Free SurfaceP=0

Free SurfaceP=0

P=γh

P=γh

Pressure on tank bottom Pressure on tank sides

04/10/2023

Hydrostatic Force on Plane Surfacex y

Where FR is the Resultant Forcehc is the vertical distance from the fluid surface to the centroid of the area and A is the area

θ

hc yc

FR

yR

AhF cR

cc

xycR

cc

xcR

xAy

Ix

yAy

Iy

= Zero in the uniform shape

Where Ixc is the 2nd moment of the area

04/10/2023

Hydrostatic Force on Plane Surface