#mechanical_phenomenon  a physical phenomenon associated with the equilibrium or motion of objects
  supertype:  physical_phenomenon  a natural phenomenon involving the physics of matter and energy
  subtype:  inertia  (physics) the tendency of a body to maintain is state of rest or uniform motion unless acted upon by an external force
     subtype:  moment_of_inertia  the tendency of a body to resist angular acceleration
  subtype:  leverage.mechanical_phenomenon__purchase  the mechanical advantage gained by being in a position to use a lever
  subtype:  sound.mechanical_phenomenon  mechanical vibrations transmitted by an elastic medium; "falling trees make a sound in the forest even when no one is there to hear them"
     subtype:  ultrasound  very high frequency sound; used in ultrasonography
     subtype:  sound_unit__soundunit  any acoustic unit of measurement
        subtype:  bel__B  a logarithmic unit of sound intensity equal to 10 decibels
        subtype:  decibel__dB__db__db  a logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity
        subtype:  sone  a unit of perceived loudness equal to the loudness of a 1000-hertz tone at 40 dB above threshold
        subtype:  phon  a unit of subjective loudness
  subtype:  trajectory__flight  the path followed by an object moving through space
     subtype:  ballistic_trajectory__ballistictrajectory__ballistics  the trajectory of an object in free flight
     subtype:  gravity-assist__gravityassist  (spaceflight) a trajectory that passes close to a planetary body in order to gain energy from its gravitational field
  subtype:  resistance.mechanical_phenomenon  any mechanical force that tends to retard or oppose motion
     subtype:  friction__rubbing  the resistance encountered when one body is moved in contact with another
        subtype:  abrasion__grinding__attrition__detrition  the wearing down of rock particles by friction due to water or wind or ice
        subtype:  adhesive_friction__grip__traction  the friction between a body and the surface on which it moves (as between an automobile tire and the road)
     subtype:  acoustic_resistance__acoustic_impedance__acoustic_reactance  opposition to the flow of sound through a surface; acoustic resistance is the real component of acoustic impedance and acoustic reactance is the imaginary component
     subtype:  retarding_force__retardingforce__drag  the phenomenon of resistance to motion through a fluid
        subtype:  sonic_barrier__sonicbarrier__sound_barrier__soundbarrier  the increase in aerodynamic drag as an airplane approaches the speed of sound
        subtype:  windage.retarding_force  the retarding force of air friction on a moving object

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