Fluids

Fluids

1. Properties of a fluid

   • They flow
     • Two types of flow: Laminar and Turbulent
       • Laminar Flow is the movement of fluids in a straight or almost straight line
       • Turbulent Flow is the broken or choppy movement of fluids
   • Are a liquid or gas
     • If a solid passes through a fluid, there is drag
   • They take the shape of their container

2. Volume is the measure of space occupied by matter

   • Can use an overflow can to measure volume
   • Can use a graduated cylinder to measure volume
     • You have to measure from the bottom of the meniscus
       • Meniscus is caused by surface tension of the liquids
   • Measuring volume is called displacement
   • Gas has no definite volume
     • Ideal gas law=pressure time volume equals gas constant time temperature

3. Volume

4. Gravity

   • Discovered by sir Isaac Newton
     • Gravity is measured in Newtons
       • Apple weighs about 100g/1N
       • Mass does not change on other planets, but weight does
         • Earth is more massive than the moon, so it has a stronger force of gravity
         • Weight is the force of gravity pulling on an object
   • Gravity comes from the greek word Gravitias
   • Gravity is the force that attracts an object to the center of the earth

5. Density

   • Density equals mass divided by volume
   • Density is the mass of a substance per unit volume of the substance
   • Increased mass, and same volume equals increased density
     • Decreased mass and same volume equals decreased density
   • Viscosity is a physical property of fluids, that describe the resistance of a substance to flow
     • Viscosity causes fluids to resist flowing
       • The denser the fluid, the more viscous it will be

6. Buoyancy

   • Is a property of all fluids
   • Buoyancy is the upward force exerted on objects
     • An object siks, because the force of gravity is stronger than buoyancy
     • Ships float because the hull is filled with air, making it less dense than water
       • Ships use ballast to alter buoyancy
         • Ballast is the weight carried on ships and hot air balloons that alter buoyancy
           • Before ballast is added, weight of cargo and passengers need to be taken into account
         • Fish use swim bladders to alter buoyancy
     • When the gravitational force and buoyant force are equal the object stays neutral
       • An object either has positive, negative, or neutral buoyancy
     • Archimedes Principle says that the buoyant force on an object is equal to the weight that is displaces

7. Pressure

   • Pressure equals force divided by area
     • Pressure is often measured in kPa (kilopascals)
       • -Pascal's Law states that all pressure exerted in a confined area exerts an equal force
     • As the velocity of a fluid increases, the pressure exerted decreases
       • Bernoullis Principle is if a fluid is moving faster, it’s pressure drops
         • Bernoulli's principle can be applied to air lifts
   • Pressure is the amount of force applied to an area
   • Smaller areas will exert more pressure
     • If an elephant were to walk on a wood floor, it would not crack
       • If a woman with the same weight of the elephant were to walk on a floor with high heels, the floor would crack