Classical Mechanics
Classical 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.
Nomenclature, Symbols, and Units
 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
Classical mechanics Glossary
 List of all Site Glossaries
 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
A
 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 Roughness  A measure of the roughness of the inside of a flowing pipe.
 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.
 Acceleration due to Gravity  See Gravitational Acceleration

Acceleration from Force  The mass and the net forces acting on the object.
 Acceleration of Gravity  See Gravitational Acceleration
 Affinity Laws  Express the mathematical relationship between the several variables involved in pump performance.
 Air Resistance  A force that opposes an object as it moves through the air.
 Angular Acceleration  The rate at which the angle velocity changes with respect to time.
 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 Displacement  The angle through which a body moves in a circular path.

Angular Momentum  How much an object is rotating around a fixed point.
 Angular Momentum of an Object with Linear Momentum  The porportion of the average net torque and the time interval the torque is applied to.
 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.
 Angular Speed  See Angular Velocity

Angular Velocity of a Rolling Sphere  Without slipping is the velocity of a point on the circumference (relative to the center of the sphere), divided by the radius of the sphere.

API Gravity  If a fluids API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks.
 Applied Force  Can come from different types of forces, one of them could be Newton's Second Law.
 Area Moment of Inertia  See Second Moment of Area
 Atmospheric Pressure  The pressure exerted upon the earth's surface by the air because of the gravitational attraction of the earth.
 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.
 Average Angular Acceleration  The average rate at which the angle velocity changes with respect to time.
 Average Angular Velocity Change in Velocity  When an object makes changes in its angular velocity at different times that is an average angular velocity of any given velocities.
 Average Velovity Change in Velovity  When an object make changes in its velocity at different times that is an average velocity of any given velocities.
 Axial Deflection  When a flex connector is compressed or stretched on it's centerline which usually occurs from the change in temperature.
 Axial Force  The force acting parallel to the longitudinal xaxis. 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.
B
 Beam Shear Stress  The horizontal shear stress of a beam.
 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 prestressed threaded assembly is loosened.
 Brinell Hardness Number  A value assigned to the hardness of metals and alloys.
C
 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.
 Change in Angular Momentum  The porportion of the average net torque and the time interval the torque is applied to.
 Characteristic Length  A dimension used in physics that defines the scale of a physical system.
 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.
 Coefficient of Friction  See Friction Coefficient
 Collinear Force  All the forces share the same line of action.
 Column Buckling Stress  The allowable buckling stress of a column.
 Concurrent Force  All of the forces act at the same point.
 Conservation Law  See Law of Conservation
 Constant Acceleration  The constant rate in a straight line at which the velocity changes with respect to time.
 Constant Angular Acceleration  An object is the constant rate at which the angle velocity changes with respect to time.
 Coplannar Parallel Force  The forces can be in the same or opposite direction and are on the same plane.
 Cyclic Deflection  The repeated change in temperature or vibration.
 Cylinder Axial Stress  The longitudinal stress parallel to the axis along a cylinder or pipe having both ends closed due to internal pressure.
 Cylinder Hoop Stress  The circumference stress in a cylinder of pipe having both ends closed due to internal pressure.
D
 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.
 Density  The ratio of the amount of matter in an object compared to its volume.

Density of an Ideal Gas  Greatly affected by pressure.
 Density of Material due to Temperature 
 Design Pressure  See working pressure
 Differential  The quantitative difference between two or more forces, pressure, time, etc.
 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.
 Drag Coefficient  See Air Resistance
E
 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.
 Elastic Modulus of Concrete  Valid for normal weight concrete.

Elasticity  Measures the stiffness of an elastic material.
 Elongation  The increase in length to which a material is to be stretched prior to rupture.
 Elongation Percentage  The percentage of elongation at the fracture.
 Energy  Never created or destroyed, First Law of Thermodynamics, but it can be transferred from one object to another.
 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.
F
 First Moment of Area  The measurement of a shape's area crosssection relative to an axis, located in space.
 First Moment of Inertia  See First Moment of Area
 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.
 Fluid Pressure at Depth  The pressure exerted on a fluid depends only on the depth of the fluid.
 Force Exerted by Contracting or Stretching a Material  Any strain exerted on a material causes an internal elastic stress.
 Fresh Air  Air taken from outdoors.
 Friction  The mechanical resistance to the relative movement of two surfaces.
 Friction Coefficient  The ratio between two contacting surfaces and the frictional force that resists the normal force of the object.
 Friction Loss  How much loss of flow through a pipe is due to the viscosity, the measure of the internal friction/resistance to the flow of a liquid near the surface of the pipe.
G
 gforce  See Gravitational Force
 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
 Gravitational Acceleration  The force on an object caused only by gravity.
 Gravitational Force  A force (force per unit mass) equal to one unit of gravity that is multiplied during a rapid change in direction or velocity

Gravitational Mass  Measured by comparing the force of gravity of an unknown mass to the force of gravity of a known mass.
 Gravitational Potential Energy  See Potential Energy
 Gravity  A force pulling togeather all matter.

Gravity Scale  See API Gravity
H
I
 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.
 Initial Velocity  The starting point at which motion begins.
 Instantaneous Acceleration  The acceleration at a particular moment in time along its path.
 Instantaneous Angular Acceleration  The rate an object rotates in a circular path at a particular moment in time.
 Instantaneous Velocity  The change in time approaches 0, is the velocity at a particular moment in time along its path.
 Internal Mass  The mass of an object measured by its resistance to acceleration when a force is applied.
J
K
 Kepler's Laws of Planetary Motion  Describe the motion of the planets in the solar system.
 Kinematics Equations  These equations are about objects in motion and their interrelationship.
 Kinematic Viscosity  The ratio of dynamic viscosity to density or the resistive flow of a fluid under the influance of gravity.
L

Lateral Deflection  When an object (flex connector) is bent off it's centerline and both of it's ends are parallel to each other.
 Launch Velocity of a Projectile 
 Law of Actions and Reaction  See Newton's Third Law
 Law of Conservation  States that the total energy of an isolated system remains constant and its physical properties are conserved over time.
 Law of Conservation of Angular Momentum  States the angular moment of a system of particles around a fixed point is conserved if there is no net external torque around that point.
 Law of Conservation of Electric Charge  States the sum of all the electric charges in any closed system is constant.

Law of Conservation of Energy  States that energy cannot be created or destroyed, but may be changed from one form to another. This means that the total energy in an isolated system remains constant over time.
 Law of Conservation of Linear Momentum  States if the net external force acting on a system of bodies is zero, then the momentum of the system remains constant.

The Law of Conservation of Mass  States that matter can neither be created or destroyed. You can mix, separate or rearrange, but the total amount of mass remains the same.
 Law of Conservation of Massenergy  States that the energy can change from one form to another, but it cannot be created or destroyed.
 Law of Conservation of Matter  States that the mass of an object or collection of objects never changes over time, even when the matter changes form.
 Law of Conservation of Mechanical Energy  States the total mecanical energy in a system remains constant as long as the only force acting are conservative forces.
 Law of Conservation of Momentum  States that momentum only moves from one place to another, since it is neither created or destroyed.
 Law of Inertia  See Newton's First Law
 Law of Resultant Torce  See Newton's Second Law
 Length  The dimension from one point to another point or the dimension from one end to the other end of an object.

Length Differential  The difference between an expanded or reduced length of an object.
 Linear Motion  A one direction motion on a one dimensional plane using acceleration, displacement, and velocity.
 Linear Strain  See Strain
 Liquid  A specific volume and can hold any shape it is contained within.
 Linear Motion  See Momentum
 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.
M
 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 Flow Rate  The average velocity of a mass that passes by a point.
 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 Rigidity  See Shear Modulus
 Modulus of Toughness  Quantifies toughness. The area under the stressstrain 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.
 Moment of Inertia  Measures the resists or change an object has to rotational acceleration about an axis.
 Moment of Momentum  See Angular Momentum
 Momentum  An object is the amount of mass in motion.
 Momentum Change in Velocity  When the velocity changes but the mass remains constant.
 Motion  The acceleration, displacement, or velocity of an object relative to a given frame of reference.
N
 Net Positive or Negative Force  Two forces can add or subtract to the net force when the forces act on each other.
 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.
 Newton's Law of Universal Gravitation  All objects in the universe exert a gravitational force of attraction on each other.
 Newton's Second Law  The force that causes an object or mass to accelerate.
 Newton's Third Law  For every action there is an equal and opposite reaction.
 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.
 Number Density  The number of items per unit volume.
 Overall Efficiency  Measures the ratio of the output of actual power to the input of actual power.
P
 Physical Properties  Those properties familiarly discussed in physics, for example, density, electrical conductivity, and thermal expansion coefficient, exclusive of those described under mechanical properties.
 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 crosssection to torsional deformation, due only to the shape of the crosssection.
 Potential Energy  The possessed energy by a body due to its relative position in a gravitational field.
 Pressure  The force exerted perpendicular to the surface of an object and is expressed as force per unit area.
 Pressure Differential  The pressure difference between two points of a system.
 Proof Stress  A specified stress to be applied to a member or structure to indicate its ability to withstand service loads.
Q
R
 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 Acceleration  The time derivative of acceleration, the second derivative of velocity or the third derivative of position.
 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.
 Resilience Modulus  The amount of energy a material can absorb and still return to its origional shape.

Rolling Coefficient  The combination of static, deformation and molecular coefficients of friction.
 Rotational Acceleration  See Angular Acceleration
 Rotational Inertia  See Moment of Inertia
 Rotational Momentum  See Angular Momentum
 Rotational Stiffness  The resist deformation of an object in response to an applied force.
 Rotational Work  Overcoming resistance for a distance by force and then adding torque.
S
 Second Area Moment  See Second Moment of Area
 Second Moment of Area  The resistance of an object to bend around a certain axis of a area crosssection.
 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 xaxis. 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 Modulus of Elasticity  See Shear Modulus
 Shear Strain  Opposing forces acting parrallel to the crosssection of a body.
 Shear Strength  The stress requied to produce a fracture in the plane of ctosssection, 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 Gravity  The density or ratio of any substance to another substance. It sometimes may be called just gravity or relative density.
 Specific Gravity of Gas  The ratio of the density of the gas to the density of air at a standard pressure and temperature.
 Specific Gravity of Soil  The mass of solids in the soil compared to the mass of water at the same volume.
 Specific Volume  A intensive variable whose physical quantity value does not depend on the amount of the substance for which it is measured.
 Specific Weight  The weight per unit volume of a substance.
 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 Efficiency  Measure of an air mover's efficiency based on its air horsepower in terms of flow and static pressure vs. required shaft input power.
 Static Friction  The force that resists relative movement and keeps objects at rest.
 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 crosssection.
 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.
 Surface Tension  The energy or force at the surface of a liquid that holds it together.
T
 Tangential Acceleration  How much the tangential velocity of a point at a radius changes with time.
 Tangential Velocity  The velocity at any point tangent to a rotating object.
 Tear Strength  Resistance of a material to tearing.
 Tension (Change in Dimension) 

Tension Strength  The capacity of a material to resist a force tending to stretch it.
 Terminal Velocity  When an object is falling under the influence of gravity but with no other influences.
 Test Time  A measurement to define a continuous series of events.
 Thermal Stress  The change in the temperature of the material that causes expansion or contraction.
 Thrust Force  See Thrust
 Time  Measurement to define a continuous series of events.
 Torque Speed 

Torsion  The stress of twisting of an object due to applied torque.
 Torsion Constant for Circle Crosssection 
 Torsional Deflection  The twisting of an object around its axis or centerline.
 Toughness  The ability of a material to absorb considerable energy without fracturing.
 Translational Momentum  See Momentum

Trajectory of a Projectile  The curved path given an initial velocity and is acted on by gravity.
 Trajectory of a Projectile on a Hill 
 Turbidity  The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye.
U
 Ultimate Tensile Strength  The maximum stress a material can resist before it starts to elongate.
 Understressing  Applying a cyclic stress lower than the endurance limit.
 Uniform Strain  The strain occuring prior to the beginning of localization of strain.
V

Vacuum  A contained space having little or no matter or a volume having a pressure lower than the outside atmospheric pressure.
 Vapor Density of Gas 
 Velocity  The rate of change or displacement with time.
 Velocity Differential  The average 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
W
 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 Force  The force of gravity or the weight.
 Wind Chill Factor  An index of the air temperature and the wind velocity.
 Wind Energy  The kinetic energy of air in motion.
 Work Done by Gas  The product of force and distance but for gas work is pressure and the volume during the change in volume.

Work Energy Theorem  The change in the kinetic energy of an object is equal to the net work done on the object.
 Working Pressure  The normal pressure that a system operates at. Also known as design pressure.
Y
 Yield Point  The point where an elastic material is permanent change in length with no extra load force.
 Yield Ratio  The ratio of yield strength to ultimate tensile strength.
 Yield Strength  The minimum stress that leads to permanent deformation of the material.
Z