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
Classical mechanics Glossary
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- 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 of Gravity - See Gravitational Acceleration
- Affinity Laws - Express the mathematical relationship between the several variables involved in pump performance.
- 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
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 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.
- 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
- 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.
- 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.
- 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
- 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
- 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.
- 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.
- First Moment of Area - The measurement of a shape's area cross-section 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-force - 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 of Effusion - See Graham's Law
- Gravitation - See 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 Potential Energy - See Potential Energy
- 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 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.
- Kepler's Laws of Planetary Motion - Describe the motion of the planets in the solar system.
- Kinematic Viscosity - The ratio of dynamic viscosity to density or the resistive flow of a fluid under the influance of gravity.
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.
- Law of Conservation of Mass-energy - 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
- 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.
- 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 Rigidity - See Shear Modulus
- Modulus of Toughness - Quantifies toughness. The area under the stress-strain curve upto fracture point.
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.
- 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 Laws of Motion - These three laws show the relations between the forces acting on a body and the motion of the body.
- 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.
- 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 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.
- 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.
- 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 Work - Overcoming resistance for a distance by force and then adding torque.
- 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 cross-section.
- 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 Modulus of Elasticity - See Shear Modulus
- 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 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 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.
- Tangential Acceleration - How much the tangential velocity of a point at a radius changes with time.
- 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 Constant for Circle Cross-section -
- Torsion Force - The force applied to the structural member or an object causing one end to twist with respect to the other end.
- 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.
- Understressing - Applying a cyclic stress lower than the endurance limit.
- Uniform Strain - The strain occuring prior to the beginning of localization of strain.
- 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
- 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.
- Wind Chill Factor - An index of the air temperature and the wind velocity.
- Work Done by Gas - The product of force and distance but for gas work is pressure and the volume during the change in 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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