section_path: Properties/Mechanical properties
section_name: Mechanical properties
paragraph_text: Mechanical properties
  
  Liquid water can be assumed to be incompressible for most purposes: its compressibility ranges from 4.4 to 5.1 × 10 Pa in ordinary conditions. Even in oceans at 4 km depth, where the pressure is 400 atm, water suffers only a 1.8% decrease in volume.
  
  The viscosity of water is about 10 Pa· s or 0.01 poise at 20 °C (68 °F), and the speed of sound in liquid water ranges between 1,400 and 1,540 metres per second (4,600 and 5,100 ft/s) depending on temperature. Sound travels long distances in water with little attenuation, especially at low frequencies (roughly 0.03 dB /km for 1 k Hz), a property that is exploited by cetaceans and humans for communication and environment sensing (sonar).