Pressure in Fluids

• What should you be able to calculate by the end of the video?

  Pressure of a fluid acting at a surface
• Why does atmospheric pressure decrease with height?

  Fewer air molecules are present at higher altitudes
• What happens to a packet of crisps on an airplane?

  The packet enlarges due to pressure differences
• What are the characteristics of gas particles?

  They are widely spaced and move rapidly
• What do gas particles do when they collide with container walls?

  They exert a force at right angles to the wall
• What term do scientists use for gases and liquids?

  Fluids
• How is pressure calculated?

  Pressure = Force / Area
• What is the unit of pressure?

  Pascal
• If a gas applies a force of 400,000 Newtons over an area of 8 m², what is the pressure?

  50,000 pascals
• Why do mountain climbers take oxygen supplies?

  Air pressure may be too low at high altitudes
• What happens to the air pressure inside a crisps packet at ground level?

  It equals the air pressure outside the bag
• How does cabin pressure in airplanes compare to ground level pressure?

  Cabin pressure is slightly lower than ground pressure
• What causes a crisps bag to inflate during a flight?

  Higher pressure inside the bag than cabin pressure
• What is the relationship between altitude and atmospheric pressure?

  • Atmospheric pressure decreases with altitude
  • Fewer air molecules at higher altitudes
  • Greater density of air at Earth's surface
• What is the formula for calculating pressure in fluids?

  • Pressure = Force / Area
  • Force is in Newtons
  • Area is in square meters
• What happens to the density of the atmosphere as altitude increases?

  • Density decreases with increasing altitude
  • Fewer air molecules in a given volume
  • Most dense at Earth's surface
• What are the implications of lower atmospheric pressure for mountain climbers?

  • Need for supplemental oxygen
  • Reduced oxygen availability at high altitudes
  • Risk of altitude sickness