Action Physics is an attribute of the dynamics of a physical system from which the equations of Motion of the system can be derived. Action Physics is the Study of Motion. Stillness is an illusion. Everything is moving. If standing still on Earth you're moving 800 miles per second or 2,880,000 MPH.

Physics

Action Theory the processes causing willful human bodily movements of a more or less complex kind.

Action Potential

Reaction Physics all forces occur in pairs such that if one object exerts a force on another object, then the second object exerts an equal and opposite reaction force on the first. The third law is also more generally stated as: "To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts." The attribution of which of the two forces is the action and which is the reaction is arbitrary. Either of the two can be considered the action, while the other is its associated reaction.

Principle of Least Action is a variational principle that, when applied to the action of a mechanical system, can be used to obtain the equations of Motion for that system. Principle of Least Effort

Water

Action Formulas

The units of Action are Energy times Time, or ML

Speed is the magnitude of its velocity (the rate of change of its position). Acceleration

Velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time.

Duration is the amount of elapsed time between two events.

D = V x T Distance equals Velocity multiplied by Time.

Flight - Gravity

Action has the Dimension of Energy x Time, where a Physical System follows simultaneously all possible paths with amplitudes determined by the action. For the action integral to be well defined the Trajectory has to be bounded in time and space.

Spatial Intelligence

Time Management

Force is any interaction that, when unopposed, will change the motion of an object. In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F. Isaac Newton

Restoring Force is a force that gives rise to an equilibrium in a physical system. If the system is perturbed away from the equilibrium, the restoring force will tend to bring the system back toward equilibrium. The restoring force is a function only of position of the mass or particle. It is always directed back toward the equilibrium position of the system. The restoring force is often to in simple harmonic motion. The force which is responsible to restore original size and shape is called restoring force.

Conservative Force is a force with the property that the work done in moving a particle between two points is independent of the taken path. Equivalently, if a particle travels in a closed loop, the net work done (the sum of the force acting along the path multiplied by the displacement) by a conservative force is zero. A conservative force is dependent only on the position of the object. If a force is conservative, it is possible to assign a numerical value for the potential at any point. When an object moves from one location to another, the force changes the potential energy of the object by an amount that does not depend on the path taken. If the force is not conservative, then defining a scalar potential is not possible, because taking different paths would lead to conflicting potential differences between the start and end points. Gravitational Force is an example of a conservative force, while Frictional Force is an example of a non-conservative force. Other examples of conservative forces are: force in elastic spring, electrostatic force between two electric charges, magnetic force between two magnetic poles. The last two forces are called central forces as they act along the line joining the centres of two charged/magnetized bodies. Thus, all central forces are conservative forces.

Harmonic Oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, F, proportional to the displacement, x:

Centrifugal Force is used to refer to an inertial force (also called a 'fictitious' force) directed away from the axis of rotation that appears to act on all objects when viewed in a rotating reference frame.

Centripetal Force is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path.

Magnetics

Fictitious Force is an apparent force that acts on all masses whose motion is described using a non-inertial frame of reference, such as a rotating reference frame.

Electromotive Force is the voltage developed by any source of electrical energy such as a battery or dynamo. It is generally defined as the electrical potential for a source in a circuit. A device that supplies electrical energy is called electromotive force or emf. Emfs convert chemical, mechanical, and other forms of energy into electrical energy. The product of such a device is also known as emf.

Coriolis Force is an inertial force (also called a fictitious force) that acts on objects that are in motion relative to a rotating reference frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one

with anticlockwise rotation, the force acts to the right. Though recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave de Coriolis, in connection with the theory of water wheels. Early in the 20th century, the term Coriolis force began to be used in connection with meteorology. Deflection of an object due to the Coriolis force is called the 'Coriolis effect'.

World's Heaviest Weight (youtube) By calibrating your Force Transducer on the world's biggest weight - 1,000,000 pounds of force. This machine ensures planes don't break apart, jets provide required thrust, and rockets make it to their destination.

Futek

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

Pressure Measurement - Gauge Pressure

Momentum is the product of the mass and velocity of an object.

Moment of Inertia determines the torque needed for a desired angular acceleration about a rotational axis.

Angular Momentum is the rotational analog of linear momentum, which is a vector quantity defined as the product of an object's mass, m, and its velocity, v. Linear momentum is denoted by the letter p and is called “momentum” for short.

What IS Angular Momentum? (youtube)

Inertia is the resistance of any physical object to any change in its state of motion (this includes changes to its speed, direction or state of rest).

List of Moments of Inertia is the mass moment of inertia, usually denoted by I, measures the extent to which an object resists rotational acceleration about a particular axis, and is the rotational analogue to mass. Mass moments of inertia have units of dimension ML2([mass] × [length]2). It should not be confused with the second moment of area, which is used in bending calculations. The mass moment of inertia is often also known as the rotational inertia, and sometimes as the angular mass.

Correspondence Rules govern the principle of replacing physical quantities with operators. Such replacements include energy and momentum, which can be derived informally from taking the time and space derivities of the plane wave function. These show a similarity to the Heisenberg Uncertainty Principle, which is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known.

Gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of the rotation of its support (e.g. vertical in the first animation). For example, on a ship: the gyroscopes, shipboard compasses, stoves, and even drink holders typically use gimbals to keep them upright with respect to the horizon despite the ship's pitching and rolling. The Space Travel Machine in the 1997 Movie named Contact, was a film adaptation of Carl Sagan's 1985 novel.

Gyroscope is a spinning wheel or disc in which the axis of rotation is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum. Because of this, gyroscopes are useful for measuring or maintaining orientation.

Caster Angle is the angular displacement of the steering axis from the vertical axis of a steered wheel in a car, motorcycle, bicycle or other vehicle, measured in the longitudinal direction.

Precession is a change in the orientation of the rotational axis of a rotating body.

Magnus Effect is the commonly observed effect in which a spinning ball (or cylinder) curves away from its principal flight path.

Spin (physics) is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei. Spinning is to revolve quickly and repeatedly around one's own axis. Head Spin (dizzy)

Rotation is a circular movement of an object around a center (or point) of rotation . A three-dimensional object always rotates around an imaginary line called a rotation axis. If the axis passes through the body's center of mass, the body is said to rotate upon itself, or spin. Rotation around a Fixed Axis

Thrust is when a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system.

Planck Constant is a physical constant that is the quantum of action, central in quantum mechanics.

Flight Envelope of an aircraft refers to the capabilities of a design in terms of airspeed and load factor or altitude.

Archer's Paradox refers to the phenomenon of an arrow traveling in the direction it is pointed at full draw, when it seems that the arrow would have to pass through the starting position it was in before being drawn, where it was pointed to the side of the target.

Trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite.

Trajectory of a Projectile is the path that a thrown or launched projectile or missile without propulsion will take under the action of gravity, neglecting all other forces, such as friction from aerodynamic drag.

Torque is the tendency of a force to rotate an object about an axis.

Torsion (mechanics) is the twisting of an object due to an applied torque. Torsion is expressed in newton per squared meter (Pa) or pound per squared inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius.

Torsion Spring twisting force - Mousetrap

Torsion Tensor is a manner of characterizing a twist or screw of a moving frame around a curve. The torsion of a curve, as it appears in the Frenet–Serret formulas, for instance, quantifies the twist of a curve about its tangent vector as the curve evolves (or rather the rotation of the Frenet–Serret frame about the tangent vector). In the geometry of surfaces, the geodesic torsion describes how a surface twists about a curve on the surface. The companion notion of curvature measures how moving frames "roll" along a curve "without twisting.

Cheetah

Vorticity is a pseudovector field that describes the local spinning motion of a continuum near some point (the tendency of something to rotate ), as would be seen by an observer located at that point and traveling along with the flow.

Capillary Action

Erosion

Magnetism

Mach's Principle local inertial frames are determined by the large scale distribution of matter, as exemplified by this anecdote: You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move? Mach's principle says that this is not a coincidence—that there is a physical law that relates the motion of the distant stars to the local inertial frame. If you see all the stars whirling around you, Mach suggests that there is some physical law which would make it so you would feel a centrifugal force. There are a number of rival formulations of the principle. It is often stated in vague ways, like "mass out there influences inertia here". A very general statement of Mach's principle is "Local physical laws are determined by the large-scale structure of the universe.

Ernst Mach was an Austrian physicist and philosopher, noted for his contributions to physics such as study of shock waves. (18 February 1838 – 19 February 1916).

Ultrarelativistic Limit is when its speed is very close to the speed of light c.

Light

Sound

Engineering

Acceleration is the rate of change of velocity of an object with respect to time. An object's acceleration is the net result of any and all forces acting on the object, as described by Newton's Second Law. The SI unit for acceleration is metre per second squared (m s−2). Accelerations are vector quantities (they have magnitude and direction) and add according to the parallelogram law. As a vector, the calculated net force is equal to the product of the object's mass (a scalar quantity) and its acceleration.

Accelerometer is a device that measures proper acceleration. Proper acceleration, being the acceleration (or rate of change of velocity) of a body in its own instantaneous rest frame, is not the same as coordinate acceleration, being the acceleration in a fixed coordinate system. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity, straight upwards (by definition) of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall (falling toward the center of the Earth at a rate of about 9.81 m/s2) will measure zero.

Velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion (e.g. 60 km/h to the north).

Terminal Velocity is the highest velocity attainable by an object as it falls through a fluid (air is the most common example, but the concept applies equally to any fluid).

Kinematics describes the motion of points (alternatively "particles"), bodies (objects), and systems of bodies without consideration of the masses of those objects nor the forces that may have caused the motion.

Fermi Acceleration is the acceleration that charged particles undergo when being repeatedly reflected, usually by a magnetic mirror (see also Centrifugal mechanism of acceleration). This is thought to be the primary mechanism by which particles gain non thermal energies in astrophysical shock waves. It plays a very important role in many astrophysical models, mainly of shocks including solar flares and supernova remnants.

Cosmic Rays

The Quantum of action in the photon is not separated into a separate piece of time and a separate piece of energy. Each ordinary (observable) Photon in the universe consists of a little piece (quantum) of non-observable action. Light

Atoms

Physics Math Information

Pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force combined with the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing.

How To Make A Pendulum Wave (Science Experiment / Physics Toy) (youtube)

Agent is a substance that exerts some force or effect. An active and efficient cause; capable of producing a certain effect.

Motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance, velocity, acceleration, time and speed. Motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame. Gravity

Newton's 3 Laws of Motion

First law If a body is at rest it remains at rest or, if it is in motion, it moves with uniform velocity, until it is acted on by a resultant force.

Second law The resultant force is equal to mass times acceleration. A resultant force, also called a net force, is a force equal to the sum of all forces applied to an object

Third law For every action, there is an equal and opposite reaction. Or every action always reacts in the opposite direction.

Philosophiae Naturalis Principia Mathematica is a work in three books by Isaac Newton, in Latin, first published 5 July 1687. After annotating and correcting his personal copy of the first edition, Newton published two further editions, in 1713 and 1726. The Principia states Newton's laws of motion, forming the foundation of classical mechanics; Newton's law of universal gravitation; and a derivation of Kepler's laws of planetary motion (which Kepler first obtained empirically). The Principia is considered as one of the most important works in the history of science.

Introduction to Motion (youtube)

Equations of Motion are equations that describe the behaviour of a physical system in terms of its motion as a function of time. More specifically, the equations of motion describe the behaviour of a physical system as a set of mathematical functions in terms of dynamic variables: normally spatial coordinates and time are used, but others are also possible, such as momentum components and time. The most general choice are generalized coordinates which can be any convenient variables characteristic of the physical system. The functions are defined in a Euclidean space in classical mechanics, but are replaced by curved spaces in relativity. If the dynamics of a system is known, the equations are the solutions to the differential equations describing the motion of the dynamics.

Reaction states that all forces occur in pairs such that if one object exerts a force on another object, then the second object exerts an equal and opposite reaction force on the first. The third law is also more generally stated as: "To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts." The attribution of which of the two forces is the action and which is the reaction is arbitrary. Either of the two can be considered the action, while the other is its associated reaction.

Body Motion (physics)

7 Myths About Movement (youtube)

Displacement (vector) is a vector that is the shortest distance from the initial to the final position of a point P. It quantifies both the distance and direction of an imaginary motion along a straight line from the initial position to the final position of the point. A displacement may be also described as a 'relative position': the final position of a point (Sf) relative to its initial position (Si), and a displacement vector can be mathematically defined as the difference between the final and initial position vectors.

Mechanics is an area of science concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment. Mechanics is the branch of physics concerned with the motion of bodies in a frame of reference. The technical aspects of doing something.

Quantum Mechanics

Dynamics (mechanics) is a branch of applied mathematics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to kinematics, which studies the motion of objects without reference to its causes. Isaac Newton defined the fundamental physical laws which govern dynamics in physics, especially his second law of motion.

Dynamics is the branch of mechanics concerned with the forces that cause motions of bodies.

Vehicular Dynamics refers to the dynamics of vehicles, here assumed to be ground vehicles. Vehicle dynamics is a part of engineering primarily based on classical mechanics.

Ricochet: Spring back; spring away from an impact.

Rebound: A movement back from an impact.

Bounce: Move up and down repeatedly.

Deflection: Turn from a straight course, fixed direction, or line of interest. Turn aside and away from an initial or intended course.

Space Travel

Work (physics) when acting there is a displacement of the point of application in the direction of the force. For example, when a ball is held above the ground and then dropped, the work done on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement).

Power (physics) is the rate of doing work."

Work (electrical) is the work done on a charged particle by an electric field. The equation for 'electrical' work is equivalent to that of 'mechanical' work.

Energy - Machines

Potentiality and Actuality is a change or activity that represents the possibility of something happening. The inherent capacity for coming into being. A possibility becomes real when knowledge of the requirements that are needed to complete a task are available. Not to say something will happen, it's saying that something could happen under the right conditions or requirements.

Action Potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory.

Membrane Potential is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential range from –40 mV to –80 mV.

Electric Potential is the amount of electric potential energy that a unitary point electric charge would have if located at any point in space, and is equal to the work done by an external agent in carrying a unit of positive charge from the arbitrarily chosen reference point (usually infinity) to that point without any acceleration.

Electric Potential Energy is a potential energy (measured in joules) that results from conservative Coulomb forces and is associated with the configuration of a particular set of point charges within a defined system.

Potential Energy is energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors. Batteries

Elasticity (physics) is the ability of a body to resist a distorting influence or deforming force and to return to its original size and shape when that influence or force is removed. Solid objects will deform when adequate forces are applied on them. If the material is Elastic, the object will return to its initial shape and size when these forces are removed. Rubber Band (wiki)

Somersaulting simulation for jumping bots. New simulation methods enable easier, faster design of elastic materials for robots and other dynamic objects.

Potential is possessing numerous possibilities. The capacity for coming into being. Having prospect and the possibility of future success. Having Capability and aptitude that may be developed. Having the skills and qualifications to do things well.

Self-Fulfillment is the realizing of one's deepest desires and capacities. A satisfying and worthwhile life well lived.

Multipotentiality is an educational and psychological term referring to the ability and preference of a person, particularly one of strong intellectual or artistic curiosity, to excel in two or more different fields. It can also refer to an individual whose interests span multiple fields or areas, rather than being strong in just one. Such traits are called multipotentialities, while "multipotentialites" has been suggested as a name for those with this trait. By contrast, those whose interests lie mostly within a single field are called "specialists."

Conservative Force is a force with the property that the work done in moving a particle between two points is independent of the taken path. Equivalently, if a particle travels in a closed loop, the net work done (the sum of the force acting along the path multiplied by the distance travelled) by a conservative force is zero.

Coulomb's Law is a law of physics that describes force interacting between static electrically charged particles.

Potential Well is the region surrounding a local minimum of potential energy. Energy captured in a potential well is unable to convert to another type of energy (kinetic energy in the case of a gravitational potential well) because it is captured in the local minimum of a potential well. Therefore, a body may not proceed to the global minimum of potential energy, as it would naturally tend to due to entropy.

Kinetic - Thermoelectric

Action-Specific Perception is when people perceive their environment and events within it in terms of their ability to act.

Physics of Tennis (PDF)

Dancing T-Handle in Zero-G, HD, free floating rotation showing a bi-stable state due to intermediate moments of inertia (youtube)

Flight is the process by which an object moves, through an atmosphere (the air in the case of earth) or beyond it (as in the case of spaceflight) without direct support from any surface. This can be achieved by generating aerodynamic lift, propulsive thrust, aerostatically using buoyancy, or by ballistic movement.

Airplane is a powered, fixed-wing aircraft that is propelled forward by thrust from a jet engine or propeller. Airplanes come in a variety of sizes, shapes, and wing configurations. Supply Chain

Jet Aircraft is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines (jet propulsion).

Dynamics of Flight

How Planes Work

The Science Behind Airplanes

Principles of Flight

Dynamics of Space Flight - NASA

HOW AIRPLANES FLY - The Science Behind Flight (youtube)

Aerodynamics is a branch of fluid dynamics concerned with studying the motion of air, particularly when it interacts with a solid object, such as an Airplane Wing. Aerodynamics is a sub-field of fluid dynamics and gas dynamics, and many aspects of aerodynamics theory are common to these fields. The term aerodynamics is often used synonymously with gas dynamics, with the difference being that "gas dynamics" applies to the study of the motion of all gases, not limited to air. Fluid Mechanics

Bernoulli's Principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. If the air flowing past the top surface of an aircraft wing is moving faster than the air flowing past the bottom surface, then Bernoulli's principle implies that the pressure on the surfaces of the wing will be lower above than below. This pressure difference results in an upwards lifting force.

Why Are Airplane Wings Angled Backwards?? (youtube)

Aerodynamic Force is exerted on a body by the air (or some other gas) in which the body is immersed, and is due to the relative motion between the body and the gas. Aerodynamic force arises from two causes: the normal force due to the pressure on the surface of the body. The shear force due to the viscosity of the gas, also known as skin friction. Pressure acts locally, normal to the surface, and shear force acts locally, parallel to the surface. The net aerodynamic force over the body is due to the pressure and shear forces integrated over the total exposed area of the body. When an airfoil (or a wing) is moving relative to the air it generates an aerodynamic force, in a rearward direction at an angle with the direction of relative motion. This aerodynamic force is commonly resolved into two components.

Drafting (aerodynamics) or slipstreaming, is a technique where two vehicles or other moving objects are caused to align in a close group reducing the overall effect of drag due to exploiting the lead object's slipstream. Especially when high speeds are involved, as in motor racing and cycling, drafting can significantly reduce the paceline's average energy expenditure required to maintain a certain speed and can also slightly reduce the energy expenditure of the lead vehicle or object.

Vortex is a region in a fluid in which the flow is rotating around an axis line, which may be straight or curved. Torus

Density of Air is the mass per unit volume of Earth's Atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in temperature or humidity.

Altitude is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, and many more). As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object.

Elevation mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface.

Wind is the flow of gases on a large scale.

Wind Direction is reported by the direction from which it originates. A northerly wind blows from the north to the south.

Thermal is a column of rising air in the lower altitudes of Earth's atmosphere, a form of atmospheric updraft. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. The Sun warms the ground, which in turn warms the air directly above it. Convection is the movement of groups of molecules within fluids such as gases and liquids, including molten rock (rheid). Convection takes place through advection, diffusion or both. Advection is the transport of a substance by bulk motion.

Gravity - Vacuum

Drag a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.

Aerodynamic Drag is the fluid drag force that acts on any moving solid body in the direction of the fluid freestream flow.

Drag Coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag. The drag coefficient is always associated with a particular surface area.

Drag (physics) sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, drag forces depend on velocity. Drag force is proportional to the velocity for a laminar flow and the squared velocity for a turbulent flow. Even though the ultimate cause of a drag is viscous friction, the turbulent drag is independent of viscosity.

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities. Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other.

Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.

When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy (that is, it converts work to heat). This property can have dramatic consequences.

Laser-cooled ions contribute to better understanding of friction

Laminar-Turbulent Transition is the process of a laminar flow becoming Turbulent, which is a flow regime in fluid dynamics characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow regime, which occurs when a fluid flows in parallel layers, with no disruption between those layers.

Fluid Dynamics describes the flow of fluids (liquids and gases).

Atmosphere - Pressure

Windshield is the front window generally made of laminated safety glass, a type of treated glass, which consists of two (typically) curved sheets of glass with a plastic layer laminated between them for safety, and are bonded into the window frame. Motorbike windshields are often made of high-impact acrylic plastic.

CAVU is an aeronautical term that stands for "Ceiling and Visibility Unlimited".

Why are plane windows round? (youtube)

Stress Concentration is a location in an object where stress is concentrated. An object is strongest when force is evenly distributed over its area, so a reduction in area, e.g., caused by a crack, results in a localized increase in stress. A material can fail, via a propagating crack, when a concentrated stress exceeds the material's theoretical cohesive strength. The real fracture strength of a material is always lower than the theoretical value because most materials contain small cracks or contaminants (especially foreign particles) that concentrate stress. Fatigue cracks always start at stress raisers, so removing such defects increases the fatigue strength.

Cabin Pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft, in order to create a safe and comfortable environment for passengers and crew flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic tanks. The air is cooled, humidified, and mixed with recirculated air if necessary, before it is distributed to the cabin by one or more environmental control systems. The cabin pressure is regulated by the outflow valve.

Weather Wiz Kids

Weather effects on Mood

STRAPPED INTO A FALLING HELICOPTER - Smarter Every Day 154 (youtube)

Autorotation is a state of flight in which the main rotor system of a helicopter or similar aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. (adjust collective pinwheel).

Advanced Robotic Bat Can Fly Like the Real Thing (youtube)

Engineers Build Robot Drone That Mimics Bat Flight

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