Fluid Mechanics

• Air Resistance

  the force that opposes the direction of motion of a body through the air
• Drag

  the force that opposes the direction of motion of a body through water
• Factors Affecting Magnitude of Air Resistance/Drag

  • velocity
  • frontal cross-sectional area
  • streamlining & shape
  • surface charateristics
• Velocity

  • the greater the velocity, the greater the air resistance/drag
  • velocity cannot be reduced to minimise air resistance/drag & therefore other factors must be considered

  e.g track cycling, speed skating, downhill skiing
• Frontal Cross-Sectional Area

  • the larger the frontal cross-sectional area, the larger the air resistance/drag
  • every effort is made to reduce the size of the frontal cross-sectional area to minimise air resistance/drag

  e.g track cycling, downhill skiing
• Streamlining & Shape

  • the more streamlined/aerodynamic the shape of a body in motion, the lower the air resistance/drag
  • streamlining is the creation if a smooth air flow around an aerodynamic shape
  • the more aerodynamic the shape of a body/equipment, the lower air resistance/drag will be

  e.g teardrop shape helmet for track cyclists
• Surface Characteristics

  • the smoother the surface, the lower the air resistance/drag
  • specially engineered clothing creates the smoothest surface possible to reduce the friction between the fluid (air or water) & the body surface

  e.g swimming, cycling, sprinting