Activity 1

Fluids

Rest

Dinamics

Density

Pressure

Flotation

Tension

Capillarity

Density is the amount of matter per unit volume

Explanation

Formula

p = Density

m = Mass

v = Volume

Examples

Force applied on a surface

Explanation

Formula

P = Pressure

F = Force

A = Area

SI Unit

Pascal (Pa) = 1N/m2

Pressure and Height

The amount of pressure an incompres-sible fluid or a liquid exerts on a body also depends on its density and depth

Explanation

Formula

P = pgh

P = Pressure

g = Gravity

h = Height

Atmospheric Pressure

The amount of pressure an incompressible fluid or a liquid exerts on a body also depends on its density and depth

Explanation

Formula

1 atm = 101,325 Pa

Also, bodies at sea level experience a pressure equivalent to 1 atm

Pascal´s Principle

Pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid, as well as to the walls of the container

Explanation

Formula

F1= Force applied on the smaller piston

A1= Area of the smaller piston

F2= Force applied by the fluid on the second piston

A2= Area of the second piston

When a body immersed in a fluid is less dense than the fluid, it will float

Explanation

"The buoyant force on an object immerced in a fluid is equal to the weigh of the fluid displaced by that object"

Archimedes Principle

B = mg = pVg

Formula

B = Flotation force

m = Mass

g = Gravity

pVg = Fluid density

Surface tension happens when a liquid´s surface acts as a membrane in tension caused by the attraction of all the molecules

Explanation

Fluid’s capacity to go up through a tube of a smaller diameter. It can elevate by having a high cohesion or decrease because of low cohesion

Formula

h= 2o/prg

h = height

o = surface tension

p = density of the liquid

r = radius of the tube

g = gravity

Flows

Laminar

Turbulent

Laminar flow presents when a fluid in motion continues in a stream line

Turbulent flow is when a fluid in motion swirls and doesn’t follow a single stream line

Volume flow rate

Explanation

Formula

Volume of a fluid that passes through a closed conduit in a period of time

Q = V/t

Q= Volume flow rate

V= Volume

T= Time

Bernoulli´s equation

Work energy equation

U = Potential energy

K = Kinetic energy

W = Work so W1 – W2 is Net Work

Explanation

"The work done on a unit volume of fluid by the surrounding fluid is equal to the sum of the changes in kinetic and potential energies per unit volume that occur during the flow."

Torricelli’s Theorem

Equation

It is used to calculate the speed at which a liquid will be moving, if there is no change in pressure and only the gravity acts on it

Explanation

​​​​​​V = speed at which the liquid comes out of the tank

G = gravitational acceleration

H = height from the hole to the water’s surface

Non Ideal Fluids

Liquids aren’t always ideal. They have viscosity and some are turbulent when flowing.

Some examples of viscous fluids are the lava of a volcano, honey or blood. They flow slowly because they are viscous

Explanation

Dimensionless parameter that depends on the speed that the fluid takes, piping diameter, fluid viscosity, etcetera

Reynolds Number

It is expressed as Re and it considers flows as

Re < 2300 Laminar flow

2300 < Re < 4000 Transition zone between laminar flow and turbulent flow

Re > 4000 Turbulent flow