Hydrostatic Pressure

Question 1

Forces acting on a object in water?

Answer 1

Weight (grav*mass) and boyancy force

Question 2

What are the stable conditions for body in water (ballast)

Answer 2

Buoyancy force above centre of Gravity.

Or for low sitting wide barge boyancy force can be below since Fb is located at centroid of displaced volume, it moves and rights the ship.

Question 3

Deinfe Hydrostatic pressure

Answer 3

For incompressible fluids at rest the pressure varies linearly with depth.

Question 4

Hydristatic pressure equation (incompress gluid at rest)

Answer 4

p= spec wt*h + psurface above

SG*spec wt h2o if different liquid

Question 5

Pressure difference between two points, what is height?

Answer 5

h= p1-p2/spec wt

SG*spec wt h2o if different liquid

Note h is called the pressure head.

Question 6

Atmosphere/gauge pressure

Answer 6

Absolute pressure is messured relative to a perfect vacuum, whereas gauge pressure is measured relative to local atmospheric pressure. Thus gauge pressure can be 0 if equal to local atmospheric pressure.

Question 7

Define the Pascal Unit.

Answer 7

N/m2 = 1 Pa

Question 8

Barometer theory formula

Answer 8

Patm= specwt*h+Pvap

Question 9

Hydrostatic force on plane

Answer 9

Fr=specwthcentrearea

Question 10

Resultant Yp point for location of resultant force

Answer 10

Yp= I/Yc*A

Or Yp= (Ic/yc*A) + Yc

Question 11

What is archimedes principle (buoyancy formula)

Answer 11

Fb = yV

Force buoy = spec wt.*volume displaced liquid