**Hydrostatics**

- Fluid statics or hydrostatics is the branch of fluid mechanics that studies “fluids at rest and the pressure in a fluid or exerted by a fluid on an immersed body”.

**Fluids**

- A fluid is a substance that continually deforms (flows) under an applied shear stress, or external force. Fluids are a phase of matter and include liquids, gases and plasmas. They are substances with zero shear modulus, or, in simpler terms, substances which cannot resist any shear force applied to them.

**Density **

- Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume: ρ = m/V.

**Surface Tension **

- Surface tension is the tendency of fluid surfaces to shrink into the minimum surface area possible. Surface tension allows insects, usually denser than water, to float and slide on a water surface.

**Pressure **

- Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior. The standard unit for pressure is the Pascal, which is a Newton per square meter.

**Atmospheric Pressure **

- Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of the air above that surface.

**Hydrostatic Pressure **

- Hydrostatic pressure is the pressure that is exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. Hydrostatic pressure increases in proportion to depth measured from the surface because of the increasing weight of fluid exerting downward force from above.

**Archimedes’ Principle **

- Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid.

**Buoyancy**

- Buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object.

**Pascal’s Law**

- Pascal’s law is a principle in fluid mechanics given by Blaise Pascal that states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.

**Flow Rate **

- Is the volume of fluid which passes per unit time; usually represented by the symbol Q (sometimes V̇). The SI unit is m3/s (cubic metres per second).

**Bernoulli’s Principle**

- Bernoulli’s principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy.

**Venturi Effect **

- The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe. The Venturi effect is named after Giovanni Battista Venturi, an Italian physicist.

**Pitot Tube**

- A pitot tube, also known as pitot probe, is a flow measurement device used to measure fluid flow velocity. The pitot tube was invented by the French engineer Henri Pitot in the early 18th century and was modified to its modern form in the mid-19th century by French scientist Henry Darcy.

**Poiseuille’s Law**

- Is a physical law that gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section.

**Laminar Flow**

- Laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing.