Pressure Facts



  • Pressure is the force created by the assault of fast-moving molecules.
  • The pressure that keeps a bicycle tire inflated is the constant assault of huge numbers of air molecules on the inside of the tire.
  • The water pressure that crushes a submarine when it dives too deep is the assault of huge numbers of water molecules.
  • Pressure rises as you go deeper in the ocean. This is because of an increasing weight of water (hydrostatic pressure) pressing down from above.
  • The water pressure 10,000 m below the surface is equivalent to seven elephants standing on a dinner plate.
  • The pressure of the air on the outside of your body is balanced by the pressure of fluids inside. Without this internal pressure, air pressure would crush your body instantly.
  • Pressure is measured as the force on a certain area.
  • The standard unit of pressure is a pascal (Pa) or 1 newton per sq m (N/m2).
  • High pressures: the center of the Earth may be 400 billion Pa; steel can withstand 40 million Pa; a shark bite can be 30 million Pa.
  • Low pressures: the best laboratory vacuum is 1 trillionth Pa; the quietest sound is 200 millionths Pa. The pressure of sunlight may be 3 millionths Pa.