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Physics Study Hub

See how motion, forces, energy, waves, electricity, light, and modern physics fit together through clear beginner-friendly lessons.

2 free pop-up tests · 217 flashcards · 26 beginner lessons

2 pop-up practice tests26 connected topics1 complete flashcard deck

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Physics Practice Center

The book includes 12 distinct practice tests: 2 printed tests, available here as online copies, and 10 additional online tests accessed through the book.

These tests cover the full physics survey. For the Core pathway, score only questions on assigned topics and use that question count as the denominator. Treat questions on untaught topics as diagnostic practice.

Your study map

Physics Course Blueprint

Open each area to see what to master. The bars show how this hub distributes its chapters, so you can plan study time without mistaking the map for an official exam weighting.

26 chapters

01 Measurement and motionBuild the measurement and motion models in Chapters 1–3. 3chapters

Chapter 1: units, vectors, graphs, and measurement
Chapters 2–3: velocity, acceleration, and free fall

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02 Forces and gravityModel interactions and circular motion in Chapters 4–5. 2chapters

Chapter 4: Newton laws and force diagrams
Chapter 5: gravitation, circular motion, and orbits

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03 Momentum, energy, and rotationCompare conservation and force models in Chapters 6–8. 3chapters

Chapters 6–7: momentum, impulse, work, and energy
Chapter 8: torque, balance, and rotational motion

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04 Matter, fluids, and thermal physicsConnect materials and thermal behavior in Chapters 9–12. 4chapters

Chapters 9–10: materials, machines, pressure, and fluids
Chapters 11–12: gases, temperature, heat, and thermodynamics

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05 Oscillations, waves, and soundInterpret periodic motion and wave behavior in Chapters 13–15. 3chapters

Chapters 13–14: oscillations, wave speed, and superposition
Chapter 15: sound, hearing, and resonance

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06 Electricity and magnetismTrace charges, circuits, and magnetic effects in Chapters 16–19. 4chapters

Chapters 16–17: electrostatics, circuits, and capacitors
Chapters 18–19: magnetism and induction

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07 Electromagnetic waves and opticsConnect signals and optical models in Chapters 20–23. 4chapters

Chapters 20–21: electromagnetic waves, reflection, and refraction
Chapters 22–23: lenses, interference, diffraction, and polarization

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08 Modern physics and scientific practiceUse modern models and evidence methods in Chapters 24–26. 3chapters

Chapters 24–25: quantum, atomic, and nuclear physics
Chapter 26: experiments, models, and data; revisit throughout the course

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Study-map shares describe the learning resources on this page. They are not presented as official test percentages.

Physics for Beginners: a free, printable set covering the topics you will see on the test, with answer keys included, so you can practice physics lessons and one skill at a time and check your own work before test day.

Free physics lessons and practice

Physics gets easier when you can see the story.

Start with a moving object, a force, a wave, or a beam of light. Then add the math. This page gives you 26 beginner lessons, two full-length tests, quick formula help, and 217 flashcards you can study at your own pace.

Start Practice Test 1 Open Physics Flashcards

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Test what you can do

Two free full-length physics tests

The online versions of the two printed practice exams are free to take here. Each is a complete 40-question form with a timer, automatic scoring, and a worked explanation for every question. Use the first as a checkup, review what you missed, then take the second when the ideas feel settled. High School Physics comes with twelve full-length forms in total: two printed exams and ten additional online forms. The complete tests sample the full 26-chapter survey. For a Core course, select taught-topic items and score only the number assigned; use untaught topics as a diagnostic. The ten additional forms are reached through the QR access page in the book.

Best first step

Practice Exam 1

The same forty questions as Practice Exam 1 in High School Physics.

40 questions
70 minutes
Full explanations

Start Test 1 Open full page

Second form

Practice Exam 2

The same forty questions as Practice Exam 2 in High School Physics.

40 questions
70 minutes
Full explanations

Start Test 2 Open full page

A calm way to begin

Start with a diagnostic, then study what you missed

You do not need to finish the book before learning where you stand. A short first pass through the test can point you toward the chapters that will help most.

Try Test 1

Work without notes. Guess when needed and keep moving, just as you would during a timed test.

Sort the misses

Mark each missed question by topic: mechanics, thermal physics, waves, electricity, light, or modern physics.

Study the matching lesson

Read the chapter explanation, copy one worked example, and solve a nearby practice problem on your own.

Return with Test 2

Take the second form after review. Compare topic by topic, by total score.

26beginner chapter lessons

2free full-length tests

40questions on each test

217searchable flashcards

Build the language first

A real flashcard study tool

Search all 217 cards, choose one part of physics, shuffle the deck, and mark each card as known or ready for another look. Your progress stays on the device you are using.

Study in this page Open full screen

Quick formula shelf

Know what each formula is saying

A formula is a compact sentence. Name the quantities and picture the situation before substituting numbers.

Motion

average speed = distance ÷ timea_avg = Δv ÷ Δt

Velocity includes direction. Acceleration describes a change in velocity.

Forces & momentum

ΣF = map = mv

Choose the system first. Then add forces or momentum as vectors.

Energy & power

K = ½mv²P_avg = E_transferred ÷ Δt

Track where energy begins, where it ends, and how quickly it moves.

Fluids & heat

ρ = m ÷ VQ = mcΔT

Density connects mass and volume. Heat is energy transferred by a temperature difference.

Waves

v = fλf = 1 ÷ T

Frequency comes from the source. Speed depends on the medium.

Circuits

V = IRP = IV

Series paths share current. Parallel branches share voltage.

Light

n = c ÷ v1/f = 1/dₒ + 1/dᵢ

Angles are measured from the normal. Keep the book’s sign convention beside you.

Atomic & nuclear

E = hfE = mc²

These relations connect energy with frequency and with mass.

The complete learning path

Twenty-six beginner lessons

Open a lesson when you want another explanation of a chapter idea. Each one opens in a new tab, so this page keeps your place.

Foundations & Mechanics

Build the language of motion, forces, energy, rotation, and matter.

Fluids, Thermal Physics & Waves

Follow pressure, heat, oscillations, waves, and sound through familiar examples.

Electricity & Magnetism

Trace charge, current, magnetic fields, induction, and communication signals.

Light & Modern Physics

See how light forms images, then meet atomic, nuclear, and experimental physics.

Common beginner mix-ups

Six pairs worth slowing down for

These words sound close, but they answer different questions. Sorting them early prevents many formula mistakes.

Distance and displacement

Distance follows the whole route. Displacement points from start to finish.

Speed and velocity

Speed has magnitude. Velocity has magnitude and direction.

Mass and weight

Mass measures inertia. Weight is the gravitational force on that mass.

Heat and temperature

Heat is transferred energy. Temperature helps determine which way thermal energy flows.

Current and voltage

Current is charge flow per unit time. Voltage is energy transferred per unit charge.

Real and virtual images

Real images form where rays meet. Virtual images form where rays only appear to meet.

Choose the part you need

Four focused practice paths

Studying one connected group can be easier than jumping across the whole book.

Mechanics

Motion, forces, gravity, momentum, energy, rotation, and materials. Chapters 1 to 9.

Open the lesson list

Thermal physics & waves

Fluids, temperature, heat, oscillations, waves, and sound. Chapters 10 to 15.

Open the lesson list

Electricity & magnetism

Charge, circuits, fields, induction, devices, and communication. Chapters 16 to 20.

Open the lesson list

Light & modern physics

Optics, quantum physics, nuclei, experiments, and data. Chapters 21 to 26.

Open the lesson list

A four-week route

One month of steady physics

Aim for 35 to 50 minutes on five days each week. Leave one day for review and one day completely free.

Week 1

Mechanics

Chapters 1 to 7. Draw every situation, label units, and explain the direction of each vector.

Week 2

Rotation, matter & waves

Chapters 8 to 15. Connect equations to balance, fluids, temperature, oscillation, and sound.

Week 3

Electricity, magnetism & light

Chapters 16 to 23. Sketch circuits, fields, ray paths, and wave patterns before calculating.

Week 4

Modern physics & testing

Chapters 24 to 26. Review flashcards, take both tests, and revisit each missed topic.

Questions beginners ask

Before you start

Do I need calculus?

No. The book and this hub use arithmetic, graphs, proportions, and introductory algebra. A few ideas point toward calculus, but you can understand the physics without taking a calculus course.

Should I memorize every formula?

Begin with the meaning of each quantity and the physical story. Keep a formula sheet nearby while practicing. The formulas you use repeatedly will become familiar on their own.

What should I do when I cannot start a problem?

Write down what is known, choose the object or system, sketch the situation, and attach a unit to every number. Then name the quantity the question asks for. Those four moves usually reveal the next step.

How should I use the practice tests?

Take Test 1 before a long review. Study each explanation and match every miss to a chapter. Use Test 2 later under timed conditions to see which topics now hold up without notes.

Will my flashcard progress be saved?

Yes, on the same browser and device. The flashcard tool stores only your known and review-again marks in your browser. It does not ask for an account.

Where should an absolute beginner begin?

Start with Chapter 1, even if the later topics look more exciting. Units, vectors, graphs, and the problem-solving routine from that chapter appear throughout the book.

Ready for your first checkup?

Set aside 70 minutes, work without notes, and mark every question you want to revisit.

Start Practice Test 1

Physics: 217 key terms and definitions

Every term from the flashcards above, written out and grouped by topic, so you can revise without clicking through the cards, search the page for a term, or print the set.

Atomic, Nuclear & Data

Accuracy: Closeness of a measurement to the true value or to a well-supported reference value.
Activity: Number of nuclear transformations per unit time in a radioactive sample, measured in becquerels. One becquerel is one transformation per second.
Atom: Smallest unit of an element that retains that element’s chemical identity.
Atomic number: Number of protons in a nucleus. The atomic number identifies the element.
Best-fit line: Straight line chosen to represent the overall trend in scattered data. It need not pass through every measured point.
Beta-plus decay: Nuclear transformation in which a proton changes into a neutron while a positron and an electron neutrino are emitted. The mass number stays the same and the atomic number falls by one.
Binding energy: Energy required to separate a nucleus completely into its protons and neutrons.
Binding energy per nucleon: Total nuclear binding energy divided by the number of nucleons. It compares average binding across nuclei of different sizes.
Causation: Relationship in which changing one factor produces a change in another. A causal claim needs control of plausible alternatives or a broader body of converging evidence.
Comparison condition: Reference condition used to judge what changed when the independent variable was changed.
Confounding variable: Unintended variable that changes with the independent variable and can provide another explanation for the result.
Controlled variable: Condition kept as consistent as practical so its changes do not confuse the effect being tested.
Correlation: Statistical association in which two variables change together. Correlation alone does not establish cause.
De Broglie wavelength: Wavelength λ=h/p associated with a particle’s quantum state, where p is momentum magnitude.
Dependent variable: Response that is measured in an investigation.
Electron capture: Nuclear transformation in which a nucleus captures an inner atomic electron, changing a proton into a neutron and emitting an electron neutrino.
Electron-volt: Unit of energy equal to 1.602176634×10^-19 J.
Extrapolation: Prediction beyond the measured or tested input range. Its model risk is greater because the tested pattern or assumptions may fail there.
Fission: Splitting of a heavy nucleus into smaller nuclei, usually producing neutrons and releasing energy.
Fusion: Joining of light nuclei to form a heavier nucleus.
Half-life: Time required for the expected number of undecayed nuclei, or the activity of a large sample, to fall by half.
Independent variable: Quantity deliberately changed in an investigation.
Interpolation: Estimate between measured values inside the tested input range.
Irradiation: Exposure to radiation. Irradiation does not necessarily make the exposed object radioactive.
Isotope: Atom with the same proton number as other atoms of its element but a different neutron number.
Mass defect: Difference between the mass of separated nucleons and the mass of their bound nucleus.
Mass number: Total number of protons and neutrons in a nucleus.
Mean: Sum of a set of values divided by the number of values.
Nucleon: Proton or neutron in a nucleus.
Nuclide: Nuclear species identified by its numbers of protons and neutrons.
Operational definition: Exact procedure used to change or measure a variable so another person can repeat the method.
Orbital: Quantum state of an electron in an atom, represented spatially by a probability distribution rather than a fixed classical path.
Percent difference: Absolute difference between two nonnegative equal-status measurements divided by their average, then multiplied by 100 percent. It is undefined when both measurements are zero.
Percent error: Absolute difference between a measured value and a defensible nonzero reference, divided by the reference magnitude, then multiplied by 100 percent.
Photoelectric effect: Ejection of electrons when individual photons supply enough energy to a material.
Photon: Packet of electromagnetic radiation with energy E=hf.
Planck’s constant: Constant h=6.62607015×10^-34 J s that connects photon energy with frequency through E=hf.
Precision: Closeness of repeated measurements to one another.
Probability density: Quantity that describes how probability is distributed through space. Denser regions of an orbital cloud represent more likely detection locations.
Quantization: Restriction of a physical quantity to particular allowed values.
Quantum uncertainty: Intrinsic limit on how sharply certain pairs of observables, such as position and momentum, can be defined together in one quantum state.
Radiation: Energy carried by electromagnetic waves or energetic particles.
Radioactive contamination: Unwanted radioactive material on or inside an object or person.
Radioactive nucleus: Nucleus that can transform spontaneously into another nuclear state or another nuclide.
Random variation: Unpredictable trial-to-trial scatter in repeated measurements. Repeating and averaging can reduce its effect on an estimated mean.
Range: Largest value minus smallest value in a set. It is a simple measure of observed spread.
Reproducibility: Agreement among measurement results when stated conditions change, such as observer, instrument, location, or time.
Residual: Measured value minus the value predicted by a model.
Sampling: Measuring an analog signal at selected times so those measurements can be processed or encoded.
Stable nucleus: Nucleus with no spontaneous transformation that has an appreciable probability on the timescale being considered.
Systematic error: Consistent shift caused by an instrument, procedure, environment, or model. Repeating the same method does not remove it.
Threshold frequency: Minimum light frequency that can produce photoelectron emission from a specified surface in the ideal one-photon model.
Wave-particle duality: Quantum behavior in which one framework predicts both wave-like patterns and localized detection events.
Work function: Minimum energy needed to remove an electron from a material’s surface.

Electricity & Magnetism

Alternating current: Electric current that reverses direction repeatedly.
Ammeter: Meter connected in series with a branch to measure the current through that branch.
Area normal: Imaginary arrow perpendicular to a surface. The angle in magnetic-flux calculations is measured from this arrow.
Branch: One circuit path between two nodes.
Capacitance: Magnitude of charge on either capacitor plate per volt of potential difference, measured in farads.
Capacitor: Pair of conductors separated by an insulating region that stores separated charge and electric-field energy.
Charge: Property of matter responsible for electric interactions, measured in coulombs.
Circuit: Connected arrangement of sources, conducting paths, and components. A closed circuit has a complete conducting path, while an open circuit has a break.
Coulomb’s law: The inverse-square relationship for the electric-force magnitude between two point charges.
Current: Rate of electric charge flow, measured in amperes.
Direct current: Electric current that keeps one conventional-current direction.
Eddy current: Circulating current induced inside a conductor by changing magnetic flux.
Electric field: Force per unit positive test charge at a point.
Electric potential: Electric potential energy per unit charge at a point, measured in volts.
Electrical conductor: Material in which mobile charge can move readily through the material.
Electrical insulator: Material in which charge remains much closer to where it was placed.
Electromagnetic induction: Production of an emf by changing magnetic flux.
Electromagnetic wave: Traveling disturbance made of linked changing electric and magnetic fields. It can carry energy through a vacuum.
Electromotive force (emf): Energy supplied per unit charge by a source or induction process, measured in volts. Despite the name, it is not a mechanical force.
Electrostatic induction: Redistribution of charge in a conductor caused by a nearby charged object. With a suitable grounding and removal sequence, it can charge the conductor without contact with the inducing object.
Electrostatics: Study of electric charge at rest and the forces, fields, potentials, and energy associated with it.
Equipotential line: Line whose points share the same electric potential. Electric-field lines cross it at right angles.
Faraday’s law: Relationship stating that induced-emf magnitude depends on how quickly magnetic flux changes and on the number of coil turns.
Generator: Device that uses mechanical work and electromagnetic induction to supply electrical energy.
Grounding: Connecting an object to Earth or another large charge reservoir so charge can flow.
Induced current: Current driven through a closed conducting path by an induced emf.
Lenz’s law: Direction rule stating that induced current produces a magnetic field that opposes the change in magnetic flux.
Magnetic domain: Region in a ferromagnetic material where many atomic magnetic moments are aligned.
Magnetic field: Vector field that describes magnetic influence. Its direction is the way a compass’s north-seeking end points, and its SI unit is the tesla.
Magnetic flux: Measure of magnetic field through a chosen surface.
Magnetic force: Force a magnetic field exerts on a moving charge, current, or magnetic material.
Magnetic pole: One of the two ends or regions of a magnet, called north and south. Like poles repel, and unlike poles attract.
Motional emf: Emf produced when a conductor moves through a magnetic field in a way that separates charge.
Motor effect: Turning effect produced when magnetic forces on different parts of a current loop create torque.
Node: Set of circuit points joined by ideal wire and therefore at the same electric potential in the ideal model.
Ohmic component: Component whose voltage is proportional to current, with constant resistance, over the stated range and under stable physical conditions.
Parallel circuit: Circuit in which branches connect to the same two nodes and therefore share the same voltage.
Potential difference: Change in electric potential energy per unit charge between two points, measured in volts.
Resistance: Relationship between voltage and current, measured in ohms. For an ohmic component, R=(V)/(I) under stable physical conditions.
Right-hand rule: Hand rule used to connect current or positive-charge motion with magnetic-field or magnetic-force direction.
Series circuit: Circuit with one current path, so the same steady current passes through each component.
Solenoid: Coil with many turns that produces a magnetic field when current passes through it.
Step-down transformer: Transformer with fewer secondary turns than primary turns, giving lower secondary voltage in the ideal model.
Step-up transformer: Transformer with more secondary turns than primary turns, giving higher secondary voltage in the ideal model.
Tesla: SI unit of magnetic-field magnitude, written T.
Transformer: Device that transfers electrical energy between circuits through changing magnetic flux in linked coils.
Voltage: Common name for electric potential difference.
Voltmeter: Meter connected across two points to measure their electric potential difference.
Weber: SI unit of magnetic flux, written Wb. One weber equals one tesla square meter.

Energy & Momentum

Angular momentum: Quantity describing rotational motion. For a rigid body rotating about a fixed axis, its component along that axis is L=Iω.
Center of mass: Point that represents the average position of a system’s mass.
Conservation law: Rule stating that a measurable total, such as energy or momentum, remains constant in an isolated system.
Efficiency: Useful output energy divided by input energy, usually written as a percentage.
Energy: Conserved quantity that can be stored or transferred, measured in joules.
Impulse: Product of net average force and time interval. Net impulse equals the change in momentum.
Kinetic energy: Energy associated with motion.
Momentum: Product of mass and velocity. Momentum is a vector.
Power: Rate of doing work or transferring energy, measured in watts.
Work: Energy transferred by the component of force along a displacement. A force perpendicular to the displacement does no work.

Light & Optics

Accommodation: Adjustment of the eye’s optical power as the lens system changes shape to focus objects at different distances.
Additive color mixing: Combining emitted light. In the ideal RGB model, balanced red, green, and blue light can produce white.
Apparent depth: Depth at which an underwater object seems to lie because refracted rays are traced backward by the eye.
Chromatic aberration: Color-dependent focusing error caused when a lens refracts different wavelengths by different amounts.
Concave mirror: Curved mirror whose reflecting surface bends inward. It converges rays that arrive parallel and close to its principal axis.
Converging lens: Lens with positive focal length that bends parallel near-axis rays toward a real focus.
Convex mirror: Curved mirror that spreads parallel reflected rays as though they came from a virtual focus behind the mirror.
Critical angle: Incident angle that produces a refracted ray along the boundary when light travels toward a lower-index medium.
Diffraction grating: Surface or screen with many evenly spaced grooves or openings that separates wavelengths through interference.
Diffuse reflection: Reflection from many differently oriented surface patches, which spreads light in many directions.
Dispersion: Separation of a wave into components because speed or refraction depends on frequency or wavelength.
Diverging lens: Lens with negative focal length that spreads parallel rays as though they came from a virtual focus.
Entrance pupil: Effective aperture opening of an optical system as viewed through its front elements. Its diameter is used in the standard f-number definition.
Eyepiece: Lens system through which a viewer looks. In a microscope or telescope, it magnifies the apparent angular size of an intermediate image.
F-number: Ratio of a lens system’s focal length to its entrance-pupil diameter. At the same focal length, a smaller f-number means a wider effective opening.
Farsightedness: Refractive error in which nearby objects would focus behind the retina when accommodation is insufficient. A converging lens commonly helps correct it.
Focal length: Signed distance from a lens or mirror to its focal point in the stated model. It is positive for a converging device and negative for a diverging device under this book’s convention.
Lens: Transparent optical element that redirects light by refraction at its surfaces.
Magnification: Signed ratio of image height to object height. Its sign gives orientation, and its magnitude gives relative size.
Nearsightedness: Refractive error in which light from a distant object would focus in front of the retina in a relaxed eye. A diverging lens commonly helps correct it.
Normal (optics): Imaginary line perpendicular to a surface at the point where a ray meets it. Reflection and refraction angles are measured from this line.
Objective: Light-collecting, image-forming optical system in a microscope or telescope: typically a lens system in a microscope or refracting telescope, and a primary mirror in a reflecting telescope.
Optical center: Central point through which a near-axis ray travels approximately straight in the thin-lens model.
Optical power: Reciprocal of focal length in meters, measured in diopters. Positive power is converging, and negative power is diverging.
Plane mirror: Flat reflecting surface that forms an upright, same-size virtual image the same distance behind the mirror as the object is in front.
Principal axis: Central reference line through a lens or curved mirror.
Ray model: Model that represents light paths with straight lines and arrowheads when the relevant objects and openings are much larger than the wavelength.
Rayleigh scattering: Scattering by particles much smaller than the wavelength. In the simplest model, shorter wavelengths scatter much more strongly than longer wavelengths.
Real image: Image formed where light rays actually converge. A screen placed at that location can display the image.
Reflection: Change in direction when a wave returns from a boundary.
Refraction: Change in wave speed at a boundary, often accompanied by a change in direction when the wave does not arrive perpendicular to the boundary.
Refractive index: Ratio n=(c)/(v) that compares light speed in vacuum with light speed in a material.
Specular reflection: Organized reflection from a smooth surface that can preserve enough ray order to form an image.
Spherical aberration: Focusing error in which rays far from the axis meet at a different distance from rays near the axis.
Subtractive color mixing: Mixing pigments, dyes, or filters that remove parts of the incident light spectrum.
Thin-lens model: Approximation that neglects lens thickness and uses near-axis rays to predict image location and magnification.
Total internal reflection: Complete reflection when light approaches a lower-index medium above the critical angle.
Virtual image: Image located where light rays only appear to originate. The rays do not actually meet at the image location.

Matter, Fluids & Thermal

Buoyant force: Upward force a fluid exerts on an object. Its magnitude equals the weight of displaced fluid.
Conduction: Energy transfer through microscopic interactions within or between touching materials.
Continuity equation: Flow relationship that expresses conservation of matter. For steady incompressible flow, A_1v_1=A_2v_2.
Convection: Energy transfer by the bulk motion of a fluid.
Density: Mass per unit volume.
Elastic deformation: Shape change that disappears when the force is removed.
Entropy: Quantity related to the number of possible microscopic arrangements. Total entropy does not decrease in an isolated system.
Heat: Energy transferred because of a temperature difference.
Ideal gas: Model of tiny particles with negligible volume, elastic collisions, and no forces between particles except during collisions.
Internal energy: Total microscopic kinetic and potential energy within a system.
Mole: Amount containing exactly 6.02214076×10^23 specified elementary entities.
Phase change: Change between states of matter, such as melting or boiling.
Pressure: Force perpendicular to a surface per unit area.
Specific heat capacity: Energy required to raise the temperature of one kilogram of a material by one kelvin.
Specific latent heat: Energy transferred per unit mass during a phase change at constant temperature for an ideal pure-substance model.
Strain: Fractional deformation, such as change in length divided by original length.
Stress (normal): Internal force perpendicular to a cross-section, divided by the cross-sectional area.
Temperature: Quantity that helps determine the direction of thermal energy transfer. In the ideal-gas particle model, absolute temperature is proportional to average translational kinetic energy.
Thermal expansion: Change in dimensions caused by a temperature change.
Young’s modulus: Ratio of tensile stress to tensile strain in a material’s linear elastic range.

Measurement & Models

Displacement: Vector change from initial position to final position.
Resolution: Smallest change an instrument can display or the smallest scale division that can be read. In optics, resolution is the ability to distinguish two nearby details as separate.
Scalar: Quantity described by magnitude alone.
System: Object or collection of objects chosen for analysis.
Uncertainty: Estimate of how far a reported value could reasonably be from the measured quantity’s value.
Vector: Quantity with both magnitude and direction.

Motion & Forces

Acceleration: Rate at which velocity changes. Acceleration can mean a change in speed, direction, or both.
Angular speed: Rate at which an object turns, without a direction sign.
Angular velocity: Rate of change of angular position, including the chosen direction of rotation.
Equilibrium: State in which the relevant net effects balance. Mechanical equilibrium requires zero net force and zero net torque.
Force: Push or pull that can change motion. Force is a vector measured in newtons.
Friction: Contact force that opposes sliding or the tendency to slide.
Inertia: Tendency of an object to resist a change in velocity. Mass measures inertia.
Lever arm: Perpendicular distance from a pivot to a force’s line of action.
Mass: Measure of an object’s inertia, measured in kilograms.
Mechanical advantage: Ratio of output force to input force.
Net force: Vector sum of all external forces acting on the chosen system.
Normal force: Contact force exerted perpendicular to a surface.
Rotational inertia: Measure of resistance to angular acceleration. It depends on mass distribution and the chosen axis.
Speed: Distance traveled per unit time.
Torque: Turning effect of a force about an axis or pivot.
Velocity: Rate of change of position, including direction.
Weight: Gravitational force on an object.

Oscillations, Waves & Sound

Amplitude: Greatest displacement from equilibrium in an oscillation or wave.
Bandwidth: Range of frequencies used or passed by a communication system or device.
Carrier wave: Repeating electromagnetic wave that is varied to carry information.
Damping: Loss of oscillation amplitude as energy leaves an oscillating system.
Decibel: Logarithmic unit used to compare sound intensity levels. A 10 dB increase means ten times the intensity.
Diffraction: Spreading of a wave around an obstacle or through an opening.
Doppler effect: Observed frequency change caused by relative motion along the line between a wave source and an observer.
Frequency: Number of complete cycles per unit time, measured in hertz.
Harmonic: Sinusoidal component whose frequency is an integer multiple of the fundamental frequency. Standing-wave modes are one application.
Hooke’s law: Ideal spring relationship F_s=-kx within the linear elastic range.
Intensity: Average power crossing each unit of area, measured in watts per square meter.
Interference: Addition of overlapping waves to form a resultant wave.
Link budget: Accounting of gains and losses that determines how much signal power reaches a receiver.
Modulation: Controlled variation of a carrier wave to encode information.
Multipath: Arrival of one signal along several reflected or direct paths, sometimes causing strengthening, weakening, or distortion.
Period: Time required for one complete cycle.
Phase: Position within a repeating cycle.
Polarization: In electrostatics, a separation of positive and negative charge within matter. For a transverse wave, the term describes the orientation of the oscillations.
Resonance: Large response when a driving frequency is near a system’s natural frequency.
Signal-to-noise ratio: Comparison of a desired signal with unwanted disturbances present at the receiver.
Simple harmonic motion: Ideal oscillation with a restoring force proportional to displacement and directed toward equilibrium.
Wave: Traveling disturbance that transfers energy and momentum without carrying matter through the full path.
Wavelength: Distance between corresponding points on consecutive wave cycles.

Complete course map

Every lesson in one place

Open a lesson in a new tab and keep this hub nearby as your study home.

26 lessons

Browse the complete lesson directory

01The Physics Toolkit: Measurement, Units, Vectors, and Graphs 02Motion: Speed, Velocity, and Acceleration 03Acceleration and Free Fall 04Forces and Newton's Laws 05Gravity, Circular Motion, and Orbits 06Momentum, Impulse, and Collisions 07Work, Energy, and Power 08Rotation, Torque, and Balance 09Matter and Materials 10Machines, Pressure, and Fluids 11Temperature, Gases, and Thermal Expansion 12Heat Transfer, Phase Changes, and Thermodynamics 13Oscillations, Springs, and Pendulums 14Wave Motion 15Sound, Hearing, and Music 16Electrostatics: Charge, Force, Field, and Potential 17Electric Circuits and Capacitors 18Magnetism 19Electromagnetic Induction, Generators, and Transformers 20Electromagnetic Waves and Communication 21Reflection, Refraction, and Color 22Lenses and Optical Instruments 23Interference, Diffraction, and Polarization 24Quantum and Atomic Physics 25Nuclear Physics, Radiation, and Half-Life 26Physics Experiments, Models, and Data

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Physics Study Hub

Physics Practice Center

Two free full-length physics tests

Practice Exam 1

Practice Exam 2

Start with a diagnostic, then study what you missed

Try Test 1

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Return with Test 2

A real flashcard study tool

Know what each formula is saying

Motion

Forces & momentum

Energy & power

Fluids & heat

Waves

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Mass and weight

Heat and temperature

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Real and virtual images

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Thermal physics & waves

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One month of steady physics

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Electricity, magnetism & light

Modern physics & testing

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Physics: 217 key terms and definitions

Atomic, Nuclear & Data

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Matter, Fluids & Thermal

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Oscillations, Waves & Sound

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