Scalar: A quantity with magnitude only Vector: A quantity with magnitude and direction Displacement: Change in position, a vector Velocity: Rate of change of position, with direction Acceleration: Rate of change of velocity Free fall: Motion under gravity alone; about 9.8 m/s^2 near Earth Projectile motion: Horizontal and vertical motions analyzed independently Newton's first law: An object keeps its motion unless a net force acts Newton's second law: Net force equals mass times acceleration Newton's third law: Forces come in equal and opposite pairs on different objects Inertia: Resistance to change in motion; related to mass Normal force: Contact force perpendicular to a surface Friction: Force opposing relative motion between surfaces Tension: Pulling force transmitted by a rope or string Weight: Gravitational force on an object, mg Free-body diagram: A sketch showing all forces on one object Centripetal acceleration: Acceleration toward the center of a circle, v^2/r Universal gravitation: F = Gm1m2/r^2 Work: Force times displacement in the force direction Kinetic energy: Energy of motion, 1/2 mv^2 Gravitational potential energy: Energy of position in a field, mgh near Earth Elastic potential energy: Energy stored in a spring, 1/2 kx^2 Hooke's law: Spring force is proportional to stretch: F = -kx Work-energy theorem: Net work equals change in kinetic energy Conservation of energy: Total energy of an isolated system stays constant Power: Rate of doing work Momentum: Mass times velocity Impulse: Force times time; equals change in momentum Elastic collision: Kinetic energy is conserved Inelastic collision: Kinetic energy is not conserved Center of mass: The average position of an object's mass Torque: A force's turning effect, rF sin theta Rotational inertia: Resistance to change in rotation Angular momentum: Rotational inertia times angular velocity Equilibrium: Net force and net torque are zero Simple harmonic motion: Oscillation with restoring force proportional to displacement Period: Time for one cycle Frequency: Cycles per second, measured in hertz Amplitude: Maximum displacement from equilibrium Pendulum period: About 2 pi sqrt(L/g) for small swings Wavelength: Distance between matching points on a wave Wave speed: v = f times wavelength Transverse wave: Vibration perpendicular to travel direction Longitudinal wave: Vibration parallel to travel direction Superposition: Waves add together where they overlap Interference: Combining waves to reinforce or cancel Standing wave: A pattern with fixed nodes and antinodes Doppler effect: Change in observed frequency due to relative motion Diffraction: Spreading of waves around obstacles or through openings Refraction: Bending of waves when speed changes between media Snell's law: n1 sin theta1 = n2 sin theta2 Total internal reflection: Light fully reflects at a boundary beyond the critical angle Converging lens: A lens that brings parallel rays together Electric charge: A property causing electric force; positive or negative Coulomb's law: Electric force between charges varies as q1q2/r^2 Electric field: Force per unit charge Electric potential: Potential energy per unit charge, in volts Capacitor: A device that stores charge and energy in an electric field Current: Rate of flow of charge, in amperes Resistance: Opposition to current, in ohms Ohm's law: V = IR Electric power: P = IV Series circuit: Components in one path; same current Parallel circuit: Components on separate branches; same voltage Kirchhoff's junction rule: Current in equals current out at a junction Kirchhoff's loop rule: Voltage changes around a closed loop sum to zero Magnetic field: A region where moving charges or magnets feel force Magnetic force on a charge: F = qvB sin theta Faraday's law: A changing magnetic flux induces an emf Lenz's law: Induced current opposes the change that caused it Pressure: Force per unit area Density: Mass per unit volume Buoyant force: Upward force equal to the weight of displaced fluid Bernoulli's principle: Faster fluid flow goes with lower pressure Continuity equation: A1v1 = A2v2 for incompressible flow Temperature: A measure of average kinetic energy of particles Heat: Energy transferred due to temperature difference Zeroth law of thermodynamics: Systems in thermal equilibrium with a third are in equilibrium with each other First law of thermodynamics: Change in internal energy = heat added minus work done by the system Second law of thermodynamics: Entropy of an isolated system never decreases Heat engine: Converts heat into work Ideal gas law: PV = nRT Photoelectric effect: Light ejecting electrons from a metal, showing its particle nature Photon: A packet of light energy, E = hf Work function: Minimum energy to free an electron from a metal de Broglie wavelength: Wavelength of a particle: h/p Wave-particle duality: Matter and light show both wave and particle behavior Energy levels: Atoms have only certain allowed energies Emission spectrum: Light at specific wavelengths from excited atoms Mass-energy equivalence: E = mc^2 Binding energy: Energy holding a nucleus together Half-life: Time for half of a radioactive sample to decay Fission: Splitting of a heavy nucleus Fusion: Joining of light nuclei Alpha decay: Emission of a helium nucleus Beta decay: A neutron becomes a proton, emitting an electron and antineutrino Free flashcards from Peabody at peabody.kids/flashcards/tp-ap-physics