9. Basic Principles of Hydrostatics

Question 1

Term

Answer 1

Definition

Question 2

Hydrostatics

Answer 2

The branch of physics that deals with the characteristics of fluids at rest.

Question 3

Buoyancy

Answer 3

The upward force exerted by a fluid that opposes the weight of an object immersed in the fluid.

Question 4

Pressure

Answer 4

The force per unit area exerted by a fluid against a surface.

Question 5

Pascal’s Law

Answer 5

States that pressure exerted anywhere in a confined fluid is transmitted equally in all directions throughout the fluid.

Question 6

Specific Gravity

Answer 6

The ratio of the density of a substance to the density of a reference substance, typically water for a liquid or solid, and air for a gas.

Question 7

Archimedes’ Principle

Answer 7

States that the buoyant force on a submerged object is equal to the weight of the fluid it displaces.

Question 8

Hydrostatic Pressure

Answer 8

The pressure at any point in a fluid at rest due solely to the weight of the fluid above it.

Question 9

Fluid

Answer 9

A substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid.

Question 10

Density

Answer 10

Mass per unit volume of a substance, typically expressed in kilograms per cubic meter (kg/m³).

Question 11

Displacement

Answer 11

The volume of fluid displaced by an object submerged in a fluid.

Question 12

Equilibrium

Answer 12

A state in which opposing forces or influences are balanced.

Question 13

Stability

Answer 13

The ability of a floating body to recover its equilibrium position after being tilted by an external force.

Question 14

Metacentre

Answer 14

The point about which a body starts oscillating when tilted in a fluid.

Question 15

Metacentric Height

Answer 15

The vertical distance between the center of buoyancy and the metacentre.

Question 16

Draft

Answer 16

The vertical distance between the waterline and the bottom of the hull.

Question 17

Free Surface Effect

Answer 17

The effect of liquids moving within tanks or compartments, potentially affecting a vessel’s stability.

Question 18

Compressibility

Answer 18

The measure of the change in volume of a fluid or solid as a response to a change in pressure.

Question 19

Viscosity

Answer 19

A measure of a fluid’s resistance to gradual deformation by shear stress or tensile stress.

Question 20

Center of Buoyancy

Answer 20

The center of mass of the displaced volume of fluid when an object is submerged.

Question 21

Submersion

Answer 21

The condition of being placed underwater, partially or fully.

Question 22

Immiscible

Answer 22

Describing two or more liquids that do not mix into each other, forming separate layers.

Question 23

Capillarity

Answer 23

The tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension.

Question 24

Surface Tension

Answer 24

The elastic tendency of a fluid surface which makes it acquire the least surface area possible.

Question 25

Cohesion

Answer 25

The intermolecular attraction between like-molecules within a substance.

Question 26

Adhesion

Answer 26

The tendency of dissimilar particles or surfaces to cling to one another.

Question 27

Hydraulic

Answer 27

Operated by the movement and force of liquid; specifically, water or oil.

Question 28

Pneumatic

Answer 28

Containing or operated by air or gas under pressure.

Question 29

Laminar Flow

Answer 29

A smooth pattern of flow characterized by parallel layers of fluid that do not mix.

Question 30

Turbulent Flow

Answer 30

A type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations or mixing.

Question 31

Reynolds Number

Answer 31

A dimensionless number used to predict flow patterns in different fluid flow situations.