Physics terms compared

Two ideas that sound interchangeable and are not. Each page states the distinction first, then shows where it changes an answer, because that is the part an exam actually tests.

Accuracy vs Precision in AP PhysicsAccuracy is closeness to the accepted value, precision is closeness of repeats to each other. What the AP Physics CED actually says, and what it asks instead.Alpha vs Beta Decay: What Is the Difference?Alpha decay ejects a helium nucleus, so the mass number drops by 4. Beta decay converts one nucleon into the other, so the mass number never changes.Ammeter vs Voltmeter: What Is the Difference?An ammeter goes in series and reads current in amps. A voltmeter goes in parallel and reads potential difference in volts. Why swapping them breaks the circuit.Ampere's Law vs Biot-Savart Law: Which to UseAmpere's law when the magnetic field is symmetric, Biot-Savart when you have to integrate. The same relationship Gauss's law has to Coulomb's law, with worked cases.Amplitude vs Wavelength: What Is the Difference?Amplitude is the height of a wave from equilibrium; wavelength is the distance along it between repeats. One is vertical, one horizontal, and neither sets the other.Angular vs Linear Acceleration: The DifferenceAngular acceleration is one number for a whole rigid body. Linear acceleration is one per point. a equals r alpha covers only the tangential part.Angular vs Linear Momentum: The DifferenceAngular momentum is measured about a point you choose, and changes when you change it. Linear momentum does not. Units, forms and the exam traps.Average vs Instantaneous VelocityAverage velocity is displacement over an interval, the slope of a secant. Instantaneous velocity is the slope of the tangent at one moment. Worked cases.Buoyant Force vs Weight: The DifferenceThe buoyant force is set by the fluid and the displaced volume; weight is set by the object. That is why floating compares densities, not weights.Celsius vs Kelvin: What Is the Difference?Celsius and kelvin have the same size degree and different zeros. That is why a temperature difference is identical in both and an absolute temperature is not.Centripetal vs Centrifugal Force: Which Is Real?Centripetal names an inward direction that real forces point. Centrifugal names no force at all, because no second object exerts an outward push.Centripetal vs Tangential Acceleration: DifferenceCentripetal acceleration turns the velocity, tangential acceleration changes its size. Both act on the same object at once, at right angles.Charge vs Current: What Is the Difference?Charge is a quantity in coulombs; current is its flow rate in amperes. Why series current is identical everywhere while charge piles up on a capacitor plate.Concave vs Convex Mirror: What Is the Difference?A concave mirror converges light and can make a real image. A convex mirror diverges it and only ever makes a virtual, upright, reduced one. Signs and examples.Conduction vs Convection: The DifferenceConduction moves energy through a material without moving it; convection carries it along with the fluid. Only conduction has an equation in AP Physics 2.Conductor vs Dielectric: The DifferenceA conductor's charges move freely and cancel the interior field. A dielectric only polarizes, cutting the field by kappa. What each does to a capacitor.Conductor vs Insulator: What Is the Difference?A conductor lets charge carriers move easily; an insulator does not. That one difference sets grounding, induced charge, and the field inside each material.Conservative vs Nonconservative ForceA conservative force does path-independent work, so it has a potential energy. A nonconservative force does path-dependent work and has none.Constant vs Conserved: What Is the Difference?Constant means a quantity does not change in time. Conserved means it cannot be created or destroyed, only moved. In a collision momentum is conserved, not constant.Constructive vs Destructive InterferenceConstructive interference is overlapping waves displacing the medium the same way, destructive is opposite ways. The path difference decides which you get.Contact vs Field Forces: What Is the Difference?A contact force needs the two objects to touch. A field force does not. The AP CED calls that kind a noncontact force, and in AP Physics 1 gravity is the only one.Converging vs Diverging Lens: The DifferenceA converging lens has a positive focal length and can form a real image. A diverging lens has a negative one and never does. Full case table and the proof.Coulomb's Law vs Gauss's Law: Which to UseCoulomb's law for point charges and superposition. Gauss's law when the symmetry is spherical, cylindrical or planar. Which one to reach for, with worked cases.Distance vs Displacement: The DifferenceDistance is how far you travelled along the path. Displacement is the change in position, start to finish. Table, worked cases, and the marks it costs.Dot Product vs Cross Product: What Is the Difference?The dot product asks how much of one vector lies along another and gives a scalar. The cross product asks how much lies perpendicular and gives a vector.Elastic vs Inelastic Collision: How to TellAn elastic collision keeps the system's total kinetic energy; an inelastic one loses some. One test separates them. Table, worked classifications, AP traps.Electric Field vs Electric Force: The DifferenceElectric force needs two charges and is measured in newtons. Electric field needs one and is measured in N/C. Why E = F/q is a definition, with worked examples.Electric Field vs Electric Potential: The DifferenceElectric field is force per charge, a vector in N/C. Electric potential is energy per charge, a scalar in volts. Worked cases where one is zero and the other is not.Electric Flux vs Magnetic Flux: The DifferenceThe definitions match word for word. The difference is on a closed surface: electric flux gives the enclosed charge over epsilon nought, magnetic flux gives zero.Electric Potential vs Electric Potential EnergyElectric potential is volts at a point in space. Electric potential energy is joules for a charge placed there. U = qV is the bridge, with worked examples.Electric vs Magnetic Field: The DifferenceAn electric field pushes any charge along the field. A magnetic field only pushes moving charges, sideways, and never does work. AP rules and worked examples.Emf vs Voltage: What Is the Difference?Emf is not a force. It is a source's potential difference at zero current, in volts. Terminal voltage falls below it once current flows. AP worked examples.Emission vs Absorption Spectrum: What Is the Difference?An emission spectrum is bright lines on a dark field; an absorption spectrum is dark lines on a continuous field. Same element, same lines, opposite contrast.Faraday's Law vs Lenz's Law: The DifferenceFaraday's law gives the size of an induced emf, Lenz's law gives its direction. They are one law and its sign convention, and the minus sign printed is Lenz's law.First vs Second Law of Thermodynamics: DifferenceThe first law of thermodynamics conserves energy. The second law fixes which way it goes. AP Physics 2 sign conventions, the entropy boundary, worked cases.Fission vs Fusion: What Is the Difference?Fission splits one nucleus into smaller ones. Fusion combines smaller nuclei into a larger one. Both conserve nucleon number and release energy via E = mc squared.Focal Length vs Radius of Curvature: f = R/2Radius of curvature is the size of the sphere a mirror was cut from. Focal length is half of it, and only the focal length appears in the mirror equation.Free Fall vs Projectile Motion: The DifferenceFree fall is projectile motion with no horizontal component. The vertical column is identical in both, which is why a dropped ball and a fired one land together.Frequency vs Wavelength: What Is the Difference?Frequency counts cycles per second and belongs to the source. Wavelength is a distance and belongs to the medium. At a boundary only the wavelength can change.Friction vs Drag: What Is the Difference?Friction is a coefficient times the normal force with no speed in it. Drag grows with speed. Only AP Physics C: Mechanics develops the drag case, in Topic 2.9.Fundamental vs Harmonic: What Is the Difference?The fundamental is the first harmonic, not a rival to it. Harmonics are the whole ladder of allowed patterns, and a pipe closed at one end has only the odd rungs.Gauge vs Absolute Pressure: The DifferenceGauge pressure counts from the local atmosphere, absolute pressure counts from vacuum, and the AP sheet prints both equations plus the one atmosphere between them.Gauss's Law vs Ampere's Law: The DifferenceA closed surface with enclosed charge against a closed loop with enclosed current. Where the parallel holds, where it breaks, and which law to reach for.Gravitational Field vs Force: The DifferenceA gravitational force needs two objects. A gravitational field is force per unit mass at a point, and it is there whether or not anything is there to feel it.Gravitational vs Electric Force: The DifferenceBoth are inverse-square laws. Gravity only attracts, the electric force is vastly stronger, and charge can be cancelled while mass cannot. Numbers included.Half-Life vs Decay Constant: What Is the Difference?Half-life is a time; the decay constant is a rate. They carry the same information, tied by lambda equals ln 2 over the half-life, and feed different equations.Heat vs Internal Energy: The DifferenceInternal energy is a property a system has right now. Heat is energy crossing its boundary during a process. One has a value, the other only has a size.Heat vs Temperature: What Is the Difference?Heat is energy on the move between systems. Temperature is a property a system has. An object can have a temperature; it cannot have an amount of heat.Heat vs Work: The Difference in ThermodynamicsHeat and work are both energy in transit, and both are positive going into the system on the AP sheet. They differ only in the mechanism of the transfer.Ideal vs Real Fluid: The DifferenceAn ideal fluid is incompressible and has no viscosity. AP Physics 1 assumes it unless told otherwise, and every fluid equation you are given depends on it.Impulse vs Force: What Is the Difference?Force acts at an instant. Impulse is force accumulated over time, so a small force acting for long can beat a huge force acting briefly.Impulse vs Momentum: What Is the Difference?Momentum is the motion a system has right now, mv. Impulse is what a net force delivers over a time interval, and it equals the change in momentum.Inductor vs Capacitor: What Is the Difference?A capacitor resists a change in voltage and stores energy in an electric field. An inductor resists a change in current and stores it in a magnetic field.Inertia vs Momentum: What Is the Difference?Inertia is an object's mass, a property it keeps even at rest. Momentum is mass times velocity and is zero at rest. One is a scalar, one is a vector.Interference vs Diffraction: What Is the Difference?Diffraction is a wave spreading around an obstacle or opening. Interference is what happens where waves overlap. Every diffraction pattern is made of interference.Internal vs External Forces: The DifferenceA force is internal if both interacting objects sit inside your system, external if one is outside. Internal forces cannot change a system's total momentum.Isobaric vs Isochoric: The DifferenceIsobaric holds pressure constant and the gas does work. Isochoric holds volume constant, so the work is exactly zero and all the heat becomes internal energy.Isothermal vs Adiabatic: The DifferenceIsothermal holds the temperature fixed, so the change in internal energy is zero. Adiabatic transfers no energy by heating, so Q is zero. One law, two terms.Kinetic vs Potential Energy: The DifferenceKinetic energy belongs to a moving object. Potential energy belongs to a system of two or more objects interacting through a conservative force.Kirchhoff's Loop vs Junction Rule: DifferenceThe loop rule is conservation of energy, the junction rule is conservation of charge. Where to apply each, the sign convention in full, and a loop worked out.Linear vs Angular Velocity: The DifferenceAngular velocity is one number for a whole rigid system. Linear velocity differs for every point on it. v equals r omega, and only in radians.Magnetic Flux vs Magnetic Field: The DifferenceA magnetic field is a vector at a point, in tesla. Magnetic flux is how much of it passes through a surface, in webers, and depends on area and angle too.Mass vs Rotational Inertia: The DifferenceMass is one number per object. Rotational inertia is one number per axis, so the same object has many values, and the parallel axis theorem tells you why.Mass vs Weight: What Is the Difference?Mass is how much matter an object has, in kilograms. Weight is the gravitational force on it, in newtons. Move the object and only the weight changes.Mechanical vs Electromagnetic Waves: The DifferenceMechanical waves need a medium and electromagnetic waves do not. That one fact decides their speeds, their geometry, and whether they cross a vacuum at all.Momentum vs Kinetic Energy: The DifferenceMomentum is a vector that grows in step with speed. Kinetic energy is a scalar that grows with speed squared. Only momentum survives every collision.Newton's Second vs Third Law: The DifferenceThe second law adds every force on one object. The third law pairs a force on object A with a force on object B, so the pair never shares a free-body diagram.Node vs Antinode: What Is the Difference?A node never moves at all; an antinode swings through the full amplitude. They alternate a quarter wavelength apart, and the boundaries decide which sits where.Object vs System in Physics: The DifferenceAn object is a thing with its internal structure ignored. A system is a collection of objects analyzed together. The choice of which to use decides the answer.Orbital vs Escape Velocity: What Is the Difference?Escape velocity is exactly the square root of two times the circular orbital speed at the same radius. Both come out of one energy statement, derived here.Period vs Frequency: What Is the Difference?Period is the seconds one cycle takes; frequency is the cycles per second. They are reciprocals, and the beat and averaging cases show why that matters.Permittivity vs Permeability: What Is the Difference?Permittivity is the electric constant, permeability the magnetic one. The AP CED defines both, the sheets print both, and their product fixes the speed of light.Photoelectric Effect vs Compton Scattering (AP Physics 2)In the photoelectric effect the photon is absorbed and vanishes, so there is a threshold frequency. In Compton scattering the photon survives with less energy.Positive vs Negative Work: What the Sign MeansThe sign of work comes from the cosine of the angle between force and displacement. Negative work means energy leaving the object, not motion in reverse.Radian vs Degree: What Is the Difference?A radian is an arc length over a radius, so it has no dimensions. That is why v equals r omega, s equals r theta and sin theta approx theta need it.RC vs LR Circuit: Time Constants ComparedBoth settle exponentially, but tau = RC and tau = L/R are built oppositely. Raising the resistance slows an RC circuit and speeds up an LR circuit.Real vs Virtual Image: What Is the Difference?A real image forms where light rays actually cross, so a screen catches it. A virtual image forms where rays only appear to come from. Sign rules and examples.Reflection vs Refraction: What Is the Difference?Reflection sends light back into the medium it came from at an equal angle. Refraction sends it into the new medium at a bent angle because its speed changes.Reflection vs Total Internal Reflection ExplainedOrdinary reflection happens at every boundary and returns part of the light. Total internal reflection returns all of it, and only beyond the critical angle.Resistance vs Resistivity: What Is the Difference?Resistance belongs to an object and is measured in ohms. Resistivity belongs to the material and is measured in ohm metres. R = rho L / A links them, with examples.Rolling vs Sliding: What Is the Difference?Rolling without slipping locks v to r omega and the contact point to rest. Sliding breaks that link and dissipates energy. The ramp race, worked.Rotational vs Translational Kinetic EnergyRotational kinetic energy is the translational kinetic energy of the parts, added up. A rolling object carries both terms at once. The analogy, exactly.Scalar vs Vector: What Is the Difference?A scalar needs only a magnitude, a vector needs a magnitude and a direction. The real difference is how they add. Full AP Physics 1 classification.Simple vs Physical Pendulum: What Is the Difference?A simple pendulum is a physical pendulum with all its mass at one distance. Watch one period formula collapse into the other, and see when it must not.Single Slit vs Double Slit: What Is the Difference?The two printed conditions look identical and locate opposite things: the single-slit equation finds dark bands, the double-slit equation finds bright ones.Slope vs Area Under a Curve: What Is the Difference?Slope gives the rate, area gives the accumulated total. Every graph the AP Physics CEDs name, the units check that catches errors, and the signed-area trap.Speed vs Velocity: What Is the Difference?Speed is how fast, velocity is how fast and which way. Same unit, different quantities: a table, a path that doubles back, and the marks it costs.Spring vs Pendulum Period: What Is the Difference?The spring period depends on the oscillating mass and the pendulum period does not. Same formula shape, opposite dependence, and the small-angle catch.Standing vs Traveling Waves: The DifferenceA traveling wave carries its pattern forward. A standing wave is two of them interfering inside a confined region, which is why only certain wavelengths fit.Static vs Dynamic Equilibrium: The DifferenceBoth mean zero net force and zero acceleration. Only the value of v differs, the physics is identical, and neither phrase appears in the AP Physics 1 CED.Torque vs Force: What Is the Difference?Torque is not a kind of force. It is what a force does about a chosen axis, so one force gives different torques about different axes, including zero.Torque vs Work: Same Units, Different QuantitiesBoth are a force times a distance and both reduce to newton metres, but only work is energy. The difference is which component of the force each one uses.Translational vs Rotational Equilibrium ExplainedZero net force and zero net torque are two separate conditions. The CED says a system can satisfy one without the other, and that is the case the exam tests.Transverse vs Longitudinal Waves: The DifferenceA transverse wave oscillates across its direction of travel and a longitudinal wave along it. The consequence that gets tested: only transverse waves polarize.Velocity vs Acceleration: What Is the Difference?Velocity is how fast position changes. Acceleration is how fast velocity changes. Negative acceleration does not mean slowing down: compare the two signs instead.Voltage vs Current: What Is the Difference?Voltage is energy per charge, in volts. Current is charge per second, in amps. One is measured across an element and one through it. Worked circuit examples.Wave Speed vs Particle Speed: What Is the Difference?Wave speed is how fast the disturbance travels, fixed by the medium. Particle speed is how fast one bit of the medium oscillates in place. They are unrelated.Weight vs Normal Force: What Is the Difference?Weight is gravity pulling the object down at mg. The normal force is a surface pushing perpendicular to itself. They match only on level ground at rest.Work Done On vs Work Done By a Gas: AP SignsOn the AP Physics 2 sheet W is the work done on the gas, so an expansion gives negative W and a compression gives positive W. Textbooks often flip it.Work vs Energy: What Is the Difference?Work is a transfer of energy by a force acting over a distance, so it is something that happens. Energy is something a system holds. Both are in joules.Work vs Power: What Is the Difference?Work is an amount of energy transferred, in joules. Power is the rate that energy moves, in watts. Same job, any power: table, worked cases, AP traps.