Grade 8 Fluids

Front

What is a Fluid

Back

Definition:

• A fluid is any substance that flows. This includes liquids and gases.
  
  

➤ Properties:

• No fixed shape — takes the shape of its container.
  
  

• Can flow and be poured.
  
  

Can exert pressure in all directions.

Front

What is Viscosity and Flow Rate

Back

➤ Viscosity:

• A measure of a fluid’s resistance to flow.
  
  

• High viscosity = flows slowly (e.g., honey).
  
  

• Low viscosity = flows quickly (e.g., water).
  
  

➤ Flow Rate:

• The speed at which a fluid flows.
  
  

• Measured in: mL/s or L/s.
  
  

• Affected by temperature:
  
  

  • Liquids: warmer = lower viscosity = faster flow.
    
    

Gases: warmer = higher viscosity.

Front

What is Density

Back

Density

➤ Definition:

• Density is how much mass is packed into a given volume.
  
  

• Formula:
  Density=Mass/Volume(D=m/V)

➤ Units:

• Mass = grams (g) or kilograms (kg)
  
  

• Volume = mL or cm³ for liquids/solids; L or m³ for gases
  
  

• Density = g/mL or kg/m³
  
  

➤ How to Find Volume:

• Regular solids:
  Use formulas (e.g., rectangular prism: V = l × w × h)
  
  

Irregular solids:
Use water displacement method

Front

What is Buoyancy and Archimedes’ Principle

Back

Buoyancy:

• The upward force a fluid exerts on an object placed in it.
  
  

• If buoyant force > object’s weight, the object floats.
  
  

➤ Archimedes’ Principle:

An object placed in a fluid experiences an upward force equal to the weight of the fluid displaced.

Front

What is  Pressure in Fluids

Back

Fluid Pressure:

• Fluids exert pressure evenly in all directions.
  
  

• Formula:
  Pressure=ForceArea(P=FA)

  • Units: Pascals (Pa) or N/m²
    
    

➤ Pascal’s Law:

• Pressure applied to a fluid is transmitted equally in all directions.
  
  

Used in hydraulic systems (e.g., brakes, lifts).

Front

What is Fluids in Technology

Back

➤ Hydraulics:

• Use of liquids under pressure.
  
  

• Based on Pascal’s Law.
  
  

• Example: car brakes, hydraulic lifts.
  
  

➤ Pneumatics:

• Use of compressed gases (usually air).
  
  

• Also based on Pascal’s Law.
  
  

Example: air tools, tire inflation systems.

Front

What is Compressibility

Back

• Liquids: not easily compressible.
  
  

Gases: easily compressible.

Front

What are the Environmental and Societal Impacts

Back

➤ Positive Uses:

• Clean drinking water systems.
  
  

• Medical technologies (e.g., syringes).
  
  

• Transportation (e.g., oil pipelines, fuel injection).
  
  

➤ Negative Impacts:

• Pollution from spills (oil, chemicals).
  
  

• Resource extraction issues (e.g., fracking fluids).
  
  

• Wastewater and fluid disposal challenges.