Classical Mechanics

classical mechanics banner 3Classical mechanics is a branch of physics that deals with the motion of bodies in accordance with the general principles by Isaac Newton's laws of mechanics.  Classical mechanics describes the motion of objects larger than a molecule and smaller than a planet, close to room temperature and going at speeds significantly slower than the speed of light.  Classical mechanics gives accurate results as long as it is limited to large objects and the speeds less than the speed of light.


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Classical mechanics Glossary


  • Abrasion  -  The destruction of a material caused by scraping or rubbing against a rough, hard surface.
  • Abrasion Resistance  -  The ability to withstand scuffing, scratching, rubbing or deterioration due to physical contact.
  • Abrasive  -  A material that is able to remove the surface of another material.
  • Absolute Vacuum  -  Contains no matter and can not be achieved.
  • Acceleration  -  The rate of change of velocity.  Whenever a mass experiences a force, an acceleration is acting.
  • Affinity Laws  -  Express the mathematical relationship between the several variables involved in pump performance.
  • Angular Deflection  -  When a flex connector is bent on it's centerline.  One end of the hose assembly is deflected or bent with the other end remaining parallel.
  • Angular Velocity  -  The speed that an object moves through an angle, θ.  The calculation below calculates ω but does not calculate the relative velocity of a point as it moves throughout the curve.
  • Average Acceleration  -  The change of velocity over an elapsed amount of time.  Whereas, instantaneous accleration is the change of velocity at a specific point in time.
  • Axial Force  -  The force acting parallel to the longitudinal x-axis.  Also called shear force.
  • Axial Stiffness  -  The ratio of the axlal load to axial deflection.  An axial load happens when a force is applied parallel to the axis of another object.


  • Breakaway Torque  -  The torque necessary to put into reverse rotation a bolt that has not been tightened.
  • Breakloose Torque  -  The torque required to effect reverse rotation when a pre-stressed threaded assembly is loosened.


  • Centripetal Force  -  The force that makes an object follow a curved path.  It is a force generated when an object keeps traveling along a axis of rotation.
  • Centrifugal Force  -  When a force pushes away from the center of a circle, but this does not really exist.

  • Centripetal Acceleration  -  The change in the velocity, which is a vector, either in speed or direction as an object makes its way around a circular path.
  • Characteristic Time  -  An estimate of the order of magnitude to the reaction time scale of a system.
  • Characteristic Velocity  -  Measure the effectiveness of the combustion of a rocket engine at high temperature and pressure, seperate from nozzle performance.
  • Circular Velocity  -  The velocity at which an object moves around a circle with a given radius.
  • Constant Acceleration  -  The constant rate in a straight line at which the velocity changes with respect to time.


  • Deceleration  -  The rate of change of velocity, this is the opposite of acceleration.
  • Deflection  -  The change in the position of something from zero or from its normal position.

  • Deformation  -  Measured by how much an object is deformed from its origional dimensions.

  • Deformation Coefficient  -  The force restricting the movement of an object that is sliding or rolling and one or both surfaces are relatively soft and deformed by the forces.

  • Degradation  -  A deleterious change in the physical properties evidenced by impairment of these properties.

  • Deionization  -  The process which removes soluble matter from water by by ion exchange using natural or synthetic resins.
  • Design Pressure  -  See working pressure
  • Diffusion  -  The spread of gases, liquids, or solids from areas of high concentration to areas of low concentration.
  • Direct Stress  -  The stress introduced in the body due to tension or compression.
  • Displacement  -  The change in position.
  • Displacement Power  -  The amount of power required to displace an object a certain distance over time with a known force.

  • Distance  -  See Length
  • Doppler Effect  -  The increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away) each other.


  • Efficiency  -  Expressed in percentage and always less than 100%.
  • Elastic Modulus  -  The ratio of the stress applied to a body or substance to the resulting strain within the elastic limits.
  • Equilibrium  -  When all the net external forces that act upon an object are balanced.
  • Escape Velocity  -  The minimum velocity required to leave a planet or moon or the minimum velocity to overcome the pull of gravity.


  • Flotation  -  A process similar to aeration in that gas (typically air) is induced or dissolved to aid in "floating" oil and suspended solids so they can be separated mechanically.
  • Force  -  The push or pull of an object resulting in a change from rest or motion.
  • Fresh Air  -  Air taken from outdoors.
  • Friction  -  The mechanical resistance to the relative movement of two surfaces.


  • Gas Oil Ratio  -  When oil is brought to surface conditions it is usual for some gas to come out of solution.  The ratio of a given volume of gas at standard pressure and temperature (STP) to a given volume of produced oil.
  • Graham's Law  -  The rate at which gases disperse is inversely proportional to the square root of their mass.

  • Graham's Law of Effusion  -  See Graham's Law
  • Gravitation  -  See Gravity



  • Impact Resistance  -  Ability to withstand mechanical blows or shock without damage seriously affecting the effectiveness of the material or system.
  • Impact Strength  -  Resistance or mechanical energy absorbed by a material to such shocks as dropping and hard blows.
  • Impulse  -  The force applied to an object over time.

  • Impulse Velocity  -  A change in momentum of an mass when a force is applied.
  • Impulse with Time  -  A change in momentum of an mass when a force is applied over time.

  • Initial Length  -  The length before linear thermal expansion.
  • Instantaneous Velocity  -  The change in time approaches 0, is the velocity at a particular moment in time along its path.



  • Kinematic Viscosity  -  The ratio of dynamic viscosity to density or the resistive flow of a fluid under the influance of gravity.    


  • Length  -  The dimension from one point to another point or the dimension from one end to the other end of an object.
  • Linear Strain  -  See Strain
  • Longitudinal Strain  -  See Strain
  • Longitudinal Stress  -  The stress imposed on the long axis of any shape.  It can be either a compressive or tensile stress.


  • Mass  -  The amount of matter an object has.
  • Mass Diffusivity  -  A proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species.
  • Mass Transfer Coefficient  -  A porportional constant to the difference in the concentrations and the rate of mass transfer.
  • Mean Free Path  -  The average distance that a object travels between collisions.
  • Mechanical Energy  -  The sum of the change in kinetic energy and potential energy generating from the force of gravity, external forces or the movement released in machine movement.
  • Mechanical Properties  -  Those properties that reveal the reaction, elastic or plastic, of a material to an applied stress, or that involved the relationship between stress and strain.
  • Modulus of Toughness  -  Quantifies toughness.  The area under the stress-strain curve upto fracture point.
  • Molar Mass  -  The mass of a given compound equal to its molecular mass in gram.

  • Molar Mass of Gas  -  The mass in atomic mass units, of one mole of a substance.

  • Molarity  -  The concentration of a solution (substance being dissolved).
  • Molecular Coefficient  -  The force restricting the movement of an object that is sliding on an extremely smooth surface or where a fluid is involved.
  • Moment  -  The tendency to cause a body to rotate around an axis.
  • Momentum  -  An object is the amount of mass in motion.


  • Newton's First Law  -  A object at rest remains at rest and a object in motion continues to move at a constant velocity unless acted upon by an external force.
  • Normal Force  -  Is always perpendicular to the surface it contacts and equal to the weight of the object.  Unless there is another external force pushing the object into the contact surface there will be no normal force.


  • Overall Efficiency  -  Measures the ratio of the output of actual power to the input of actual power.


  • Plasma  -  It is everywhere in the universe and the most common of all matter.  Of all types of matter it is closest to a gas.
  • Poisson's Ratio  -  The elastic ratio between lateral strain and longitudinal strain.
  • Polar Moment of Inertia  -  Defines the resistance of a cross-section to torsional deformation, due only to the shape of the cross-section.
  • Potential Energy  -  The possessed energy by a body due to its relative position in a gravitational field.
  • Power  -  The rate of doing work or the rate of using energy per unit time.
  • Pressure  -  The force exerted perpendicular to the surface of an object and is expressed as force per unit area.
  • Proof Stress  -  A specified stress to be applied to a member or structure to indicate its ability to withstand service loads.



  • Radius of Gyration  -  The distance from the axis of rotation to a point where the total mass of the body is supposed to be concentrated.
  • Rate of Change in Velocity  -  The first derivative of velocity, the second derivative of position or the instantaneous change in velocity.  In physics, it is known as acceleration.
  • Relativistic Mass  -  The mass of a body which changes with the speed of the body as this speed approaches close to the speed of light.
  • Rest Mass  -  When the body is at rest and motionless, and is also relative to an observer moving or not moving.
  • Rotational Work  -  Overcoming resistance for a distance by force and then adding torque.


  • Service Factor  -  Used to reduce a strength value to obtain an engineering design stress.
  • Shear Carriage  -  Bottom section of the shear that rises when a cut is made and catches the pieces of scrap.  Located at the weld.
  • Shear Crack  -  A diagonal, transgranular crack caused by shear stresses.
  • Shear Force  -  The force acting perpendicular to the longitudinal x-axis.  Also called axial force. 
  • Shear Modulus  -  The ratio of the tangential force per unit area applied to a body or substance to the resulting tangential strain within the elastic limits.
  • Shear Strain  -  Opposing forces acting parrallel to the cross-section of a body.
  • Shear Strength  -  The stress requied to produce a fracture in the plane of ctoss-section, the condition of loading being so much that the directions of force and of resistance are parallel and opposite although their paths are offset a specified minimum amount.
  • Shear Stress  -  Tends to deform the material by breaking rather than stretching without changing the volume by restraining the object.
  • Solid  -  Has particles that are compressed together in an orderly pattern.
  • Specific Volume  -  A intensive variable whose physical quantity value does not depend on the amount of the substance for which it is measured.
  • Specific Mass  -  See Density
  • Speed  -  The rate of change or distance with time.

  • Speed of Light  -  A speed which remains constant irrespective of the speed of the source of the light or of the observer.
  • Speed of Sound  -  The distance traveled for a specific time through a medium from particle to particle.

  • Stagnation Pressure  -  The pressure a fluid exerts when the velocity of the fluid is zero.
  • Static Pressure  -  The difference in air pressure between the suction side and pressure side of a blower.
  • Statics  -  Concerns itself with forces when no change in momentun occurs.
  • Stiffness  -  The resistance of the elastic deformation of an object that applies to both compression and tension.
  • Stopping Distance  -  When a vehicle is moving at a certain velocity then has to come to a complete stop, the distance from applying the brakes to complete stop is the stopping distance.
  • Strain  -  The deformation, stretched or compressed, of a material compared to its original length.
  • Strain Energy  -  The energy stored in an elastic body of the material undergoing deformation.
  • Stress  -  The force per unit area of cross-section.
  • Surface Fatigue Wear  -  Repeated rolling or sliding contact, in which the shear stresses bring about microcracks, particles and form wear pits that destroy the surface.
  • Surface Pressure  -  The lateral force per unit length applied on a line perperdicular to the force.


  • Test Time  -  A measurement to define a continuous series of events.
  • Thrust Force  -  See Thrust
  • Time  -  Measurement to define a continuous series of events.
  • Torque  -  A measure of how much twisting is applied to a fastener.
  • Torsion Force  -  The force applied to the structural member or an object causing one end to twist with respect to the other end.
  • Toughness  -  The ability of a material to absorb considerable energy without fracturing.
  • Turbidity  -  The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye.


  • Understressing  -  Applying a cyclic stress lower than the endurance limit.
  • Uniform Strain  -  The strain occuring prior to the beginning of localization of strain.


  • Velocity  -  The rate of change or displacement with time.
  • Velocity Gradient  -  How the velocity of a fluid changes between parallel planes or different points within the fluid.
  • Vibration Resistance  -  The property of a material to resist mechanical vibration without wearing away, settling or dusting.
  • Volumetric Mass Density  -  See Density


  • Wear  -  Wear is brought about from the gradual removal of particles due to contacting surfaces in motion, usually sliding, generally as a result of mechanical action.
  • Weight  -  Weight is a force on an object accelerated by gravity.
  • Weight Density  -  The basic difference between density and weight is that weight is a measure of the amount of matter in an object, whereas density measures the amount of matter in a unit volume.
  • Working Pressure  -  The normal pressure that a system operates at.  Also known as design pressure.


  • Yield Point  -  The point where an elastic material is permanent change in length with no extra load force.
  • Yield Strength  -  The minimum stress that leads to permanent deformation of the material.




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Impulse Velocity
Abrasion Resistance
Absolute Roughness

Tags: Glossaries