Phys.General
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166 terms
Terms | Definitions |
|---|---|
 Acceleration | Vector quantity describing a change in velocity over the elapsed time for which that change occurs. a = Δv/Δt |
| Displacement | Vector quantity describing the straight-line distance between an initial and a final position of some particle or object. |
| Scalar | Quantity that has only a magnitude but no direction, ie speed. |
| Speed | Scalar quantity describing the distance traveled over the time required to travel that distance. |
| Vector | Quantity with both magnitude and direction: velocity, acceleration, force, momentum, etc. |
| Velocity | Vector quantity describing an object's displacement over the elapsed time. v = Δx/Δt |
| Centripetal Acceleration | Acceleration of an object traveling in a circle with a constant speed, equal in magnitude to the velocity squared divided by the radius of the circle traversed (v²/r). Direction of the acceleration always points towards the center of the circle. |
| Force | Vector quantity describing the push or pull on an object. SI unit for force is the Newton, N. |
| Friction Force | Antagonistic force that points parallel and opposite in direction to the (attempted) movement of an object expressed as the product of friction coefficient and the force normal, static, kinetic (Ff = µN) or angular (tanθ = µ). |
| Gravity | Ubiquitous attractive force existing between any two objects, whose magnitude is directly proportional to the product of the two masses observed and inversely proportional to the square of their distance from each other. (F = G([m₁*m₂]/r²]) where G is the gravitational constant. |
| Mass | Scalar quantity used as a measure of an object's inertia. |
| Newton's First Law | A body at rest or constant velocity will remain so unless acted upon by an outside net force. |
| Newton's Second Law | Force = mass*acceleration. A net force acting on a body will have a net acceleration in the direction of the net force, proportional to the body's mass. |
| Newton's Third Law | If a body exerts a force (F) on another body, there will be an equal and opposite reaction (-F). |
| Normal Force | Perpendicular component of the force caused when two surfaces push against each other, denoted by Fn. |
| Rotational Equilibrium | State where the sum of the torques acting on a body is zero, giving it no net angular acceleration. |
| Torque | Magnitude of a force acting on a body times the perpendicular distance between the acting force and the axis of rotation, denoted by τ with the SI unit Nm (Newton meter). τ = radius*Force |
| Translational Equilibrium | State where the sum of the forces acting on an object is zero, giving it no net acceleration. |
| Weight | Force that measures the gravitational pull on an object, given as the product of the object's mass times its gravitational acceleration (mg, where g(Earth) = 9.8m/s²). |
| Center of Gravity | Point on some object or body at which the entire force of gravity is considered to act on the object. |
| Center of Mass | The point on some object/body at which all of its mass is considered to be concentrated. |
| Completely Elastic Collision | Type of collision in which both momentum and kinetic energy are conserved. The sum of initial and final kinetic energies in a collision are equal. (initial) m₁v₁ + m₂v₂ = (final) m₁v₁ + m₂v₂ |
| Completely Inelastic Collision | Type of collision in which the two bodies stick together after colliding, resulting in a single final mass and velocity. Momentum is conserved, Kinetic Energy is not. m₁v₁ + m₂v₂ = (m₁+m₂)vf |
| Conservation of Mechanical Energy | When only conservative forces act on an object and work is done, energy is conserved and described by the equation: ΔE = ΔKE + ΔPE = 0 |
| Conservation of Momentum | Momentum of a system remains constant when there are no net external forces acting on it. |
| Conservative Force | A force, such as gravity, that performs work over a distance that is independent of the path taken. |
| Impulse | Often denoted by 'j,' it is the change in momentum, given by Δp |
| Kinetic Energy | Energy of an object in motion, calculated by the equation KE = 1/2mv² given in the SI unit Joules (J) |
| Momentum | Often denoted as p, it is a vector quantity, as the product of an object's mass and velocity. p = mv |
| Nonconservative Force | A force, like friction, that performs work over a distance that is dependent on the path taken between the initial and final positions. |
| Potential Energy | Energy of an object due to its height of ground level. PE = mgh |
| Power | Rate at which work is doen, given by the equation. P = W/Δt |
| Work | Quantity measured when a constant force acts on a body to move it a distance d. Calculated as W = Fdcosθ, cosθ indicates the component force parallel to motion direction. |
| Work-Energy Theorem | Theorem stating that net work performed on an object is related to the change in kinetic energy of that body. W = ΔKE |
| Calorie | Unit of heat (C), 10³ calories (c), 4184 Joules. |
| Conduction | Form of heat transfer where heat energy is directly transferred between molecules through molecular collisions or direct contact. |
| Convection | Heat transfer applying to fluids (liquids and gases) where heated material transfers energy by bulk flow and physical motion. |
| First Law of Thermodynamics | Change in internal energy of a system (ΔU) is equal to the heat (Q) transferred into the system minus the energy lost by the system when it performs work (W). ΔU = Q - W |
| Heat of Fusion | Heat of transformation corresponding to a phase change from either solid to liquid or liquid to solid. |
| Heat of Transformation | Amount of heat required to change the phase of a substance, calculated by (substance mass)*(substance's heat of transformation) q = mL. |
| Heat of Vaporization | Heat of transformation corresponding to a phase change from liquid to gas or gas to liquid. |
| Kelvin | Most commonly used temperature scale (SI units), ranges up from absolute zero. Tk = Tc +273 |
| Pressure | Force per unit area : F/A |
| Radiation | Heat transfer by electromagnetic waves, which can travel through a vacuum. |
| Second Law of Thermodynamics | When a thermodynamic process moves a system from one state of equilibrium to another, the entropy (S) of that system combined with that of its surroundings will either increase or remain unchanged; irreversible processes will increase entropy, reversible processes will leave entropy unchanged. |
| Temperature | Measure of heat content that a body possesses, measured in Kelvin, Celsius or Fahrenheit. |
| Thermal Expansion | Expansion of a solid as a result of increasing temperatures. ΔL = αLΔT. L = Length, α = coefficient of linear expansion, T = temperature. |
| Thermodynamics | Study of heat transfer and its effects. |
| Volume Expansion | Expansion in volume of a liquid as a result of increasing temperatures, calculated by ΔV = ßVΔT. V = volume, ß = coefficient of volume expansion, T = temperature. |
| Absolute Pressure | Pressure below the surface of a liquid that depends on gravity and surface pressure, calculated by P = P₀ + ρgz. P = Absolute pressure. z is depth. P₀ is the surface pressure. ρ = is the density. |
| Adhesion | Type of attractive force that molecules of a liquid feel toward molecules of another substance, such as in the adhesion of water droplets to a glass surface. |
| Archimedes' Principle | Body that is fully or partially immersed in a liquid will be buoyed up by a force that is equal to the weight of the liquid displaced by the body. F(buoyant) = ρ(liq)gV(obj submerged) = ρ(obj)gV(obj). V(obj) |
| Bernoulli's Equation | Equation describing the conservation of energy in fluid flow, given by P₁ + (1/2)ρV₁² + ρgy₁ + P₂ + (1/2)ρv₂² + ρgy₂. |
| Bulk Modulus | A term that describes a fluid's resistance to compression under a pressure, denoted by B and measured by the ratio of stress (pressure change) to strain: ΔP/(ΔV/V) |
| Cohesion | Type of attractive force felt by liquid molecules toward each other. Cohesion is responsible for surface tension. |
| Continuity Equation | Equation following the law that the mass flow rate of fluid must remain constant from one cross-section of a tube to another, given by A₁V₁ = A₂V₂ |
| Density | Scalar quantity defined as the mass per unit volume, often denoted by ρ. |
| Gauge Pressure | Pressure above the atmospheric pressure, given only by ρgz; the difference between P(absolute) and P₀ |
| Laminar Flow | Simplest type of liquid flow through a tube where thin layers of liquid slide over one another, occurring as long as the flow rate remains below a critical velocity Vc |
| Pascal's Principle | Principle stating that when a pressure is applied to one point of an enclosed fluid, that pressure is transmitted in equal magnitude to all points within that fluid and to the walls of its container. This principle forms the basis of the hydraulic lift. |
| Shear Modulus | Term describing a solid's resistance to shear stress, denoted by S and measured by the ratio of shear stress (F/A) to strain (x/h). Results when a force is applied parallel to the surface area. |
| Specific Gravity | Dimensionless quantity given by the density of a substance divided by the density of water, where ρ(water) = 1g/ml, or 1g/cm³. ρ(x)/ρ(water) |
| Streamline | Lines that trace the path of water particles as they flow in a tube without ever crossing each other. |
| Turbulent Flow | Type of liquid flow that occurs when the flow rate in a tube exceeds Vc. Motion of the fluid that is not adjacent to the container walls is highly irregular, forming vortices and a high flow resistance. |
| Viscosity | Measure of internal friction in a fluid, often denoted by µ |
| Young's Modulus | Term used in characterizing the elasticity of a solid, denoted by Y and measured by the ratio of the stress (F/A) to strain (ΔL/L). Results when force is applied perpendicular to the surface area. |
| Coulomb | SI unit of electric charge, denoted as C |
| Coulomb's Law | Law describing the electrostatic force that exists between two charges, q₁ and q₂, given as F(coul) = (kq₁q₂)/r² |
| Dipole Moment | Vector quantity resulting from an electric dipole, equal to the product of the charge magnitude q and the distance separating the two charges d, often denoted by p. |
| Electric Dipole | Result of having two charges of opposite sign and equal magnitude separated by a short distance d. |
| Electric Field | Electrostatic force that a source charge qs would exert on a positive test charge q₀ within its proximity divided by that test charge; E = F(coul)/q₀ |
| Electric Field Lines | Imaginary lines that show the direction in which a positive test charge is accelerated by the coulombic force due to the electric field of a source charge. |
| Electric Potential | Amount of electric potential energy per unit charge; the work required to bring a positive test charge q₀ from infinity to within an electric field of another positive source charge Q, divided by that test charge, calculated by the equation V = (kQ)/r |
| Electric Potential Energy | Amount of work required to bring a test charge q₀ from infinity to a point within the electric field of some source charge Q, given by the equation EPE = q₀V |
| Electrostatics | Study of electric charges at rest or in motion and the forces between them. |
| Equipotential Lines | Concentric circles emanating from a source charge that cross its electric field lines perpendicularly. No work is required for a test charge to travel along the circumference of one of these since the potential at every point along that line is the same. |
| Fundamental Unit of Charge | Smallest measured electric charge, belonging to an electron. -1.6 X 10⁻¹⁹C |
| Potential Difference | Also called Voltage (ΔV). Difference in electric potential between two points in an electric field |
| Current | Flow of charge as it moves across a potential difference (voltage), denoted as I and measured by the amount of charge passing through a conductor over a unit of time: I=Δq/Δt [Ampere=A=C/s] |
| Diamagnetic Material | Material whose atoms have no net magnetic field. The material is therefore repelled from the pole of a magnet. |
| Ferromagnetic Material | Material whose atoms have net magnetic field and, below a critical temperature, are strongly attracted to a magnet pole. |
| Loop-Wire Magnetic Field | Magnetic field produced at the center of a circular loop of current-carrying wire, with a radius of r, calculated by: B = µ₀i/2r |
| Magnetic Field | Field Vectors created by moving charges and permanent magnets that in turn exert a magnetic force on moving charges and current-carrying wires. |
| Magnetic Force | Force exerted on a charged particle moving through a magnetic field, calculated using the equation, F(B) = qvBsinθ, where the angle denotes that only charges moving perpendicular to the magnetic field experience a force. |
| Magnetic Force on Current-Carrying Wire | Equation used to measure the force exerted on a current-carrying wire, due to a magnetic field, given by F = I L Bsinθ. I = current, L = length of the wire, B = magnitude of the magnetic field, θ = angle at which the wire intersects B-Field vectors. |
| Paramagnetic Material | Material whose atoms have a net magnetic field; under conditions that allow the alignment of the individual magnetic fields, the material exhibits an attraction toward the pole of a magnet. |
| Permeability of Free Space, µ₀ | Term denoted by µ₀ and equal to 4∏ X 10⁻⁷. Tesla meter/ampere; used in the equation measuring the magnetic field produced by a current-carrying wire, B = µ₀I/2∏r. |
| Right Hand Rule | Common method used to determine the direction of the magnetic force vector. Thumb points in the direction of charge's velocity, fingers point in direction of magnetic (B) field, palm points in the direction of the acting force. |
| Straight-Wire Magnetic Field | Magnetic field produced at a perpendicular distance r, from a straight current-carrying wire, calculated by: B = µ₀i/2∏r |
| Alternating Current | Current that flows through a conductor in two directions that are periodically altered. |
| Capacitance | Measure of a capacitor's ability to store charge, calculated by the ratio of the magnitude of charge on one plate to the voltage across the two plates, expressed in SI units, farads. |
| Capacitor | Electric device used in circuits that is composed of two conducting plates separated by a short distance and works to store electric charge. |
| Conductor | Material in which electrons can move with relative ease. |
| Dielectric | Insulating material placed between the two plates of a capacitor. If the circuit is plugged into a current source, more charge will be stored in the capacitor. If the circuit is not plugged into a current source, the voltage of the capacitor will decrease. |
| Dielectric Constant | Dimensionless number that indicates the factor by which capacitance is increased when a dielectric is placed in between the plates of a capacitor, given by C' = KC, where C' is the new capacitance. |
| Direct Current | Current that flows through a conductor in one direction only. |
| Electric Circuit | A conducting pathway that contains one or more voltage sources that drive an electric current along that pathway and through connected passive circuit elements, such as resistors. |
| Electromotive Force | Energy gained by an electron when it is accelerated through a potential difference of 1 volt, given by qV where q is 1.6 x 10⁻¹⁹ C and V is 1 volt. |
| Electron Volt | Voltage created by a potential difference between the two terminals of a cell when no current is flowing. |
| Insulator | Material in which electrons cannot move freely. |
| Kirchhoff's Laws | A.) In accordance with the conservation of electric charge, the sum of currents directed into a node or junction point in a circuit equals the sum of the currents directed away from that point. B) Sum of the voltage sources in a circuit loop is equal to the sum of voltage drops along that loop. |
| Ohm's Law | Law stating that the voltage drop across a resistor is proportional to the current flowing through it, given by V = IR |
| Permittivity of Free Space | ε₀. Used in the calculation of capacitance, given by the equation C = ε₀A/d. A = area of one plate. d = distance between the plates. |
| Power Dissipated by Resistor | Rate at which the energy of flowing charges through a resistor is dissipated given by the equation P = IV |
| Resistance | Natural tendency of a conductor to block current flow to a certain extent resulting in loss of energy or potential. Resistance is equal to the ratio of the voltage applied to the resulting current. |
| Resistivity | Intrinsic property of a conductor denoted by ρ used to measure its resistance in the equation R = ρ L/A. L = length of the conductor, A = cross-sectional area. |
| RMS Current | Quantity used to calculate the average dissipated in an AC circuit, given by I(max)/(√2). Must be used because the average current, when calculated conventionally, equals zero as a result of the periodic nature of that current. |
| RMS Voltage | V(max)/(√2); average voltage in an AC circuit, where voltage alternates in a sinusoidal pattern. |
| Amplitude | Point of maximum displacement from the equilibrium position. |
| Angular Frequency | ω. equal to √(k/m) |
| Anti-Node | Point of maximum displacement in a standing wave. |
| Beats | Periodic frequency resulting from the superposition of two waves that have slightly different frequencies. f(beat) = |f₁-f₂| |
| Constructive Interference | When two overlapping waves are in phase and their amplitudes add together. |
| Destructive Interference | When two overlapping waves are out of phase, they subtract and cancel each other out if they have the same amplitude and are 180˚ out of phase |
| Doppler Effect | When a source emitting a sound and a detector receiving the sound move relative to each other, the virtual frequency vf' detected is less than (distance increases) or greater (distance decreases) than the actual emitted frequency. f' = f(V±V(d))/(V±Vs) |
| Frequency | Number of cycles per second measured in SI units of Hz, where 1 Hz = 1 cycle/second |
| Fundamental Frequency | Lowest frequency a standing wave can support, given by f = nv/2L for strings fixed at both ends, f = nv/4L for pipes open at one end, n = 1 when pipes are closed at one end; first harmonic. |
| Harmonic Series | All the possible frequencies a standing wave can support. |
| Hook's Law | Equation describing the restoring force of a mass-spring system, given by F = -kx, where x is the displacement from the equilibrium position. |
| Intensity | Power transmitted per unit area, given by P = IA. I = Intensity, A = Area, P = Power. |
| Longitudinal Wave | Type of wave, such as sound, whose oscillation is along the direction of its motion. |
| Node | Point of zero displacement in a wave. |
| Period | Number of seconds it takes to complete one cycle, denoted by T; the inverse value of frequency. |
| Phase Difference | Angle by which the sine curve of one wave leads or lags the sine curve of another wave. |
| Resonance | If a standing wave undergoes a forced oscillation due to an external periodic force that has a frequency equal to the natural frequency of the oscillating system, the amplitude will reach a maximum. |
| Simple Harmonic Motion | Motion of an object oscillating back and forth about some equilibrium point when it is subject to an elastic linear restoring force. |
| Sound Level | A quantity measured in decibels (dB) and denoted by ß. Given by ß = 10logI/I₀. I₀ = reference intensity of 10⁻¹²W/m². |
| Spring Constant | A measure of a spring's stiffness, denoted by k. |
| Transverse Wave | Type of wave, such as light, whose oscillation is perpendicular to its direction of motion. |
| Wavelength | Quantity Equal to the distance between any two equivalent consecutive points along a wave, such as two consecutive crest peaks, expressed as λ. |
| Wave Speed | Speed of a wave, related to the frequency and wavelength. v = fλ |
| Converging Lens | Lens with a thick center that converges light rays at a point where the image is formed. |
| Converging Mirror | Concave mirror with a positive focal length. |
| Diffraction | Spreading-out effect of light when it passes through a small slit opening. |
| Dispersion | Phenomenon observed when white light is incident on the face of a prism and emerges on the opposite side with all its wavelengths split apart. Occurs because λ is related to the index of refraction by the expression n = c/fλ. Therefore a small λ has a large n and, in turn, a small angle of refraction (θ₂) |
| Diverging Lens | Lens with a thin center that diverges light after refraction and always forms a virtual image. |
| Diverging Mirror | Convex mirror with a negative focal length. Diverging mirrors always produce virtual images. |
| Electromagnetic Spectrum | Full range of frequencies and wavelengths for electromagnetic waves broken down into the following region, in order of descending/decreasing λ: radio, infrared, visible light, ultraviolet, X-ray, Gamma Ray. |
| Electromagnetic Waves | When a magnetic field is changing, it causes a change in an electric field and vice versa, resulting in the propagation of a transverse wave containing a magnetic and an electric field that are perpendicular to each other. |
| Focal Length | Distance between the focal point and the mirror or lens. For spherical mirrors, focal length is equal to one-half the radius of curvature. |
| Index of Refraction | Ratio of the speed of light in a vacuum to the speed of light through a medium, given by: n = c/v; factor by which the c is reduced as light travels from a vacuum into another medium. |
| Interference | When superimposed light waves are in phase, their amplitudes add (constructive interference) and the appearance is brighter. When superimposed light waves are out of phase, their amplitudes subtract (destructive interference) and the appearance is darker. |
| Law of Reflection | Law stating that when light waves strike a medium, the angle of incidence θi is equal to the angle of reflection θr |
| Magnification | Dimensionless value denoted by m given by the equation: m = -i/o, where i is image height and o is object height. A negative m denotes an inverted image, whereas a positive m denotes an upright image. |
| Plane Mirror | Mirror in which incident light rays remain parallel after reflection, always producing a virtual image that appears to be the same distance behind the mirror as the object is in front of the mirror. |
| Plane-Polarized Light | Light that has been passed through a polarizing filter, allowing only the transmission of waves containing electric field vectors parallel to the lines of the filter. |
| Real Image | An image produced at a point where the light rays actually converge or pass through. For mirrors, this would be on the side of the object, for lenses, it would be on the opposite side of the object. |
| Snell's Law | Equation describing the angle of refraction for a light ray passing from one medium to another, given by n₁sinθ₁ = n₂sinθ₂, where n is the index of refraction. |
| Speed of Light | Speed of electromagnetic waves traveling through a vacuum, given by the equation c = λf = constant equal to 3.00 x 10⁸m/s |
| Spherical Mirror | Curved mirror that is essentially a small, cut-out portion of a sphere mirror, having a center of curvature C and a radius of curvature r. |
| Total Internal Reflection | Condition in which the θ₁ of light traveling from a medium with a high n to a medium with a low n is greater than the critical angle θc resulting in all of the light being reflected with none being refracted. |
| Virtual Image | An image produced at a point where light does not actually pass or converge. For mirrors, this would be the opposite side of the object; for lenses, it would be on the same side as the object. |
| Fluorescence | Phenomenon observed when an atom is excited by UV light and the electrons return to the ground state in two or more steps, emitting photons of lower frequency (often in the visible light spectrum) at each step. |
| Photoelectric Effect | Phenomenon observed when light of a certain frequency is incident on a sheet of metal and causes it to emit an electron. |
| Work Function | Minimum amount of photon energy required to emit an electron from a certain metal. This quantity, denoted by W, is used to calculate the residual kinetic energy of an electron emitted by a metal, given by KE = hf - W. hf is the energy of a photon, |
| Alpha Decay | Nuclear reaction in which an α-particle (⁴₂He) is emitted. |
| Beta Decay | Nuclear reaction in which a ß-particle (e⁻) is emitted. |
| Binding Energy | Energy that holds the protons and neutrons together in the nucleus, defined by the equation E = mc². m = mass defect, c = speed of light in a vacuum. |
| Electron Capture | Radioactive process in which a nucleus captures an inner-shell electron that combines with a proton to form a neutron. As a result, the atomic number decreases by 1, but the atomic mass remains the same. |
| Exponential Decay | A decrease in the amount of substance N, given by: N = N₀ x e^(-λt) |
| Fission | Nuclear reaction in which a large nucleus splits up into smaller nuclei. |
| Fusion | Nuclear reaction in which two or more small nuclei combine to form a larger nucleus. |
| Gamma Decay | Atomic emission of high energy photons, aka γ-particles. |
| Half-Life | Amount of time it takes for one-half of a radioactive sample to decay, given by the equation T1/2 = ln2/λ. λ = decay constant. |
| Mass Defect | Difference between an atom's atomic mass and the sum of its protons and neutrons. |
| Positron | An anti-electron, denoted ß+ or e+, emitted in a nuclear reaction. |
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