OSAT Physics (OK114) key terms

A cyclical process of forming a testable question, building a hypothesis, designing controlled experiments, collecting and analyzing data, and revising explanations based on evidence rather than authority or intuition.

The procedure of stating a falsifiable prediction and comparing measured results against it, often using a null hypothesis and a statistical test to decide whether observed differences exceed random variation.

A quantity held constant across trials so that changes in the measured outcome can be attributed to the independent variable rather than to incidental differences in conditions.

The digits in a measurement that carry meaningful information about precision, including all certain digits plus one estimated digit; results of multiplication and division keep the fewest significant figures among the inputs.

A method of checking or deriving relationships by tracking the base units of each quantity, since both sides of any valid physical equation must reduce to identical dimensions.

The internationally agreed measurement system built on seven base units, including the meter, kilogram, second, ampere, kelvin, mole, and candela, from which all other units are derived.

The estimated range within which a measured value plausibly lies, arising from instrument resolution, random fluctuation, and systematic bias; it is reported alongside the value and propagates through calculations.

A consistent offset in measurements caused by a flawed instrument, miscalibration, or biased procedure, which shifts results in one direction and is not reduced by averaging repeated trials.

A scalar is fully described by magnitude alone, such as mass or temperature, while a vector requires both magnitude and direction, such as displacement, velocity, acceleration, and force.

The projections of a vector onto perpendicular axes, found with sine and cosine, which allow a two-dimensional problem to be split into independent one-dimensional problems that are solved separately and then recombined.

Three principles stating that objects maintain constant velocity absent net force, that net force equals mass times acceleration, and that forces between two bodies are equal in magnitude and opposite in direction.

A sketch isolating one object and drawing every external force acting on it as an arrow from the object, used to write the net-force equations for each axis.

The tendency of an object to resist changes in its state of motion, quantified by its mass; a more massive object requires a larger net force to achieve the same acceleration.

The normal force is the perpendicular contact push from a surface; friction is the parallel resistance opposing relative sliding or attempted sliding, proportional to the normal force through a coefficient of friction.

Two-dimensional motion under gravity alone, in which horizontal velocity stays constant while vertical motion accelerates downward, producing a parabolic path when air resistance is negligible.

Motion at constant speed along a circular path, requiring a centripetal acceleration directed toward the center and provided by a net inward force such as tension, gravity, or friction.

The net inward force that keeps an object moving on a curved path, equal to mass times speed squared divided by radius; it is a role filled by real forces, not a separate kind of force.

The statement that the net work done on an object equals its change in kinetic energy, linking force applied over a displacement to the resulting change in speed.

Kinetic energy is the energy of motion, one-half mass times speed squared; potential energy is stored energy due to position or configuration, such as gravitational or elastic potential energy.

The principle that total energy in an isolated system stays constant, though it may convert among kinetic, potential, thermal, and other forms; energy is never created or destroyed.

The product of an object's mass and velocity, a vector quantity whose total in an isolated system remains constant during collisions and explosions.

The product of average force and the time interval over which it acts, equal to the change in momentum; extending contact time reduces the peak force for a given momentum change.

In an elastic collision both momentum and kinetic energy are conserved; in an inelastic collision momentum is conserved but some kinetic energy converts to heat, sound, or deformation.

The rotational analog of linear momentum, equal to moment of inertia times angular velocity; it stays constant when no external torque acts, explaining why a spinning skater speeds up when pulling in her arms.

The rotational effect of a force, equal to force times lever-arm distance times the sine of the angle between them; it changes an object's angular acceleration rather than its linear acceleration.

The energy-conservation statement for thermal systems: the heat added to a system equals the change in its internal energy plus the work the system does on its surroundings.

Named paths between states: isothermal at constant temperature, adiabatic with no heat exchange, isobaric at constant pressure, and isochoric at constant volume, each giving a distinct work term.

The relationship pressure times volume equals the number of moles times the gas constant times absolute temperature, describing how a fixed amount of dilute gas responds to changes in state.

A model treating a gas as many small particles in random motion whose average kinetic energy is proportional to absolute temperature, explaining pressure as collisions with container walls.

The principle that heat flows spontaneously from hot to cold and that the total entropy of an isolated system never decreases, setting the direction of real processes and limiting heat-engine efficiency.

Characteristics shared by all waves: wavelength, frequency, amplitude, speed, and phase, related by speed equaling frequency times wavelength; frequency is set by the source, speed by the medium.

When waves overlap, their displacements add; crests meeting crests produce constructive reinforcement while crests meeting troughs produce cancellation, producing stable patterns for coherent sources.

Reflections in a bounded medium superpose into fixed nodes and antinodes; resonance occurs at frequencies whose wavelengths fit the boundary conditions, producing large amplitude from small driving.

The shift in observed frequency when source and observer move relative to each other: approaching raises pitch, receding lowers it, and light shows a redshift or blueshift.

The bending of light as it crosses between media of different speeds, described by the ratio of indices of refraction equaling the inverse ratio of the sines of the incidence and refraction angles.

Image location and size follow from the thin-lens or mirror equation and magnification; real images form where light actually converges, virtual images where rays only appear to diverge.

Diffraction is the spreading of waves around obstacles or through slits, producing interference patterns; polarization restricts a transverse wave's oscillation to one plane, confirming light is transverse.

The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation, attractive for opposite signs and repulsive for like signs.

The electric field is force per unit positive charge at a point; electric potential is potential energy per unit charge, and potential difference drives current through a circuit.

The electric flux through any closed surface equals the enclosed charge divided by the permittivity constant, a convenient tool for finding fields of highly symmetric charge distributions.

For many conductors, current equals voltage divided by resistance; resistance grows with length and resistivity and shrinks with cross-sectional area, and power dissipated equals current squared times resistance.

In series, components share one current path and voltages add; in parallel, components share the same voltage and currents add, giving a total resistance smaller than any branch.

Junction rule: current into a node equals current out, reflecting charge conservation. Loop rule: the sum of voltage changes around any closed loop is zero, reflecting energy conservation.

A charge moving through a magnetic field experiences a force perpendicular to both its velocity and the field, so magnetic forces do no work and deflect charges into circular or helical paths.

A changing magnetic flux through a loop induces a voltage proportional to the rate of change, with the induced current opposing the change that produced it; this underlies generators and transformers.

Light above a threshold frequency ejects electrons from a metal immediately, with maximum electron energy depending on frequency rather than intensity, evidence that light arrives in discrete photons.

A photon's energy equals Planck's constant times frequency; atoms emit or absorb only photons matching energy-level differences, producing characteristic line spectra used to identify elements.

Electrons in an atom occupy discrete allowed energies; transitions between levels release or absorb photons of specific wavelengths, and the ground state is the lowest permitted energy.

Quantum objects show wave behavior such as interference and particle behavior such as localized detection; the de Broglie relation assigns a wavelength inversely proportional to momentum.

Unstable nuclei transform spontaneously, emitting alpha particles, beta particles, or gamma rays; activity decreases exponentially with a characteristic half-life independent of temperature and chemistry.

The time required for half the nuclei in a sample to decay, or for activity to fall by half; after n half-lives the remaining fraction is one-half raised to the n.

Mass and energy are interchangeable according to energy equals mass times the speed of light squared; small mass defects in nuclear reactions appear as large released energies.

The ordered range of electromagnetic radiation from long-wavelength radio through microwave, infrared, visible, ultraviolet, X-ray, and short-wavelength gamma rays, all traveling at light speed in vacuum.

Practices and labeling systems that identify chemical, electrical, thermal, and radiation hazards, specify required protective equipment, and dictate spill, burn, and exposure responses before work begins.

Barriers worn to reduce exposure, including splash goggles, gloves matched to the chemical, lab coats, and closed-toe shoes; selection depends on the specific hazard rather than convenience.

Organizing measurements into tables and graphs, choosing axes to linearize relationships, fitting a best-fit line, and interpreting slope and intercept in physical units to extract a result.