MSCE Physics key terms

The systematic process of asking questions, forming testable hypotheses, gathering evidence through observation or experiment, and revising explanations based on results. It emphasizes repeatability, peer scrutiny, and openness to falsification rather than appeals to authority.

A proposed, testable explanation for an observed pattern that predicts a specific outcome. A useful hypothesis is falsifiable: some conceivable measurement could show it wrong. It is provisional and may be revised or discarded as evidence accumulates.

A factor deliberately held constant across experimental trials so it cannot influence the outcome. Keeping such factors fixed lets a researcher attribute changes in the dependent variable to the manipulated independent variable rather than to confounding influences.

A simplified representation of a physical system, often mathematical or conceptual, that captures the features relevant to a question while ignoring others. Models generate predictions and are judged by how well those predictions match measurement.

The digits in a measured value that carry meaningful information about precision, including one estimated digit. Rules for counting them govern how computed results are rounded so reported precision does not overstate what the instruments actually support.

The quantified range within which a measured value plausibly lies, reflecting instrument resolution, random scatter, and systematic bias. It is reported alongside a result and propagated through calculations so conclusions reflect measurement limits.

A repeatable offset in measurements caused by a flaw such as miscalibration, a zero error, or a biased procedure. Unlike random scatter, it shifts results consistently in one direction and is not reduced by averaging many trials.

A technique of checking equations and converting units by treating physical quantities as products of base dimensions such as length, mass, and time. Both sides of a valid equation must have identical dimensions.

The seven foundational units of the International System: metre, kilogram, second, ampere, kelvin, mole, and candela. All other units are derived from these by multiplication and division, and since 2019 most are defined via fixed constants.

A scalar is a quantity fully described by magnitude alone, such as mass or temperature. A vector has both magnitude and direction, such as displacement or force, and vectors combine by components rather than simple arithmetic addition.

The vector change in position from an initial point to a final point, with magnitude and direction. It differs from distance travelled, which is the total path length and is a scalar that can exceed the displacement magnitude.

The rate of change of displacement at a single moment, equal to the slope of the position-time graph at that point. It is the limit of average velocity as the time interval shrinks toward zero.

The rate at which velocity changes with time, a vector quantity. It arises from changes in speed, direction, or both, so an object moving at constant speed around a curve is accelerating because its direction changes.

The two-dimensional motion of an object launched into the air and thereafter acted on only by gravity, ignoring air resistance. Horizontal and vertical components are independent: horizontal velocity stays constant while vertical velocity changes at rate g.

The net force on an object equals its mass times its acceleration, expressed as a vector equation. It links cause (net force) to effect (acceleration) and shows that acceleration points along the net force, not necessarily along velocity.

A sketch isolating one object and drawing every external force acting on it as an arrow from the object, with a labelled coordinate system. It is the standard first step in applying Newton's laws to a mechanics problem.

The force that opposes the start of sliding between surfaces in contact, adjusting up to a maximum value proportional to the normal force. Once motion begins, kinetic friction, usually smaller, replaces it.

The net work done on an object by all forces equals its change in kinetic energy. This relation connects force and displacement descriptions of motion to the scalar accounting of energy, often simplifying problems where forces vary.

In a system where only conservative forces such as gravity or spring forces do work, the sum of kinetic and potential energy stays constant. Non-conservative forces like friction convert mechanical energy to thermal energy.

The rate at which work is done or energy is transferred, measured in watts, equal to work divided by elapsed time. For a constant force it also equals the force times the velocity component along that force.

If the net external force on a system is zero, its total momentum remains constant. This principle governs collisions and explosions, allowing unknown velocities to be found from known masses and initial motion.

The product of a force and the time interval over which it acts, equal to the change in momentum it produces. Extending the contact time reduces the peak force needed for a given momentum change, as in airbags.

A collision in which both total momentum and total kinetic energy are conserved. Billiard-ball impacts approximate this ideal; in inelastic collisions momentum is still conserved but kinetic energy is partly converted to other forms.

The ratio of useful energy output to total energy input for a device or process, often expressed as a percentage. The remainder is dissipated, typically as thermal energy, and the value can never exceed one hundred percent.

Oscillation in which the restoring force is proportional to displacement and directed toward equilibrium, producing sinusoidal motion. The period is independent of amplitude for an ideal spring-mass system or pendulum at small angles.

A large amplitude response that occurs when a driving frequency matches a system's natural frequency. Energy transfer from the driver is then maximal, which explains tuning, musical instrument tone, and structural vibration hazards.

The rate at which a wave disturbance travels through a medium, equal to frequency times wavelength. It depends on the medium's properties, so a wave crossing into a new medium changes speed and wavelength while frequency stays fixed.

The change in direction of a wave as it passes between media in which it travels at different speeds. The bending follows Snell's law and underlies lenses, prisms, and the apparent depth of submerged objects.

The complete reflection of light at a boundary when it strikes from the denser medium beyond the critical angle. It occurs because no refracted ray can exist past that angle and is the basis of optical fibres.

The shift in observed frequency when a wave source and observer move relative to each other. Approaching motion raises the observed frequency and receding motion lowers it, an effect used in radar and medical imaging.

The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation. It acts along the line joining them and is attractive for opposite signs.

The force per unit positive charge at a point in space, a vector pointing away from positive charge and toward negative charge. Field lines map its direction and relative strength in a region.

The work needed per unit charge to move a charge between two points in an electric field, measured in volts. It is a scalar, unlike the electric field, and drives current through a circuit.

For a conductor at constant temperature, current is directly proportional to potential difference across it, with resistance as the constant of proportionality. Components that disobey this linear relation are called non-ohmic.

The generation of an electromotive force in a conductor by a changing magnetic flux through it. Faraday's law quantifies it, and Lenz's law states the induced effect opposes the change that produced it.

The relation that pressure times volume equals the number of moles times the gas constant times absolute temperature for a dilute gas. It links the macroscopic variables of state and underlies kinetic theory predictions.

The model explaining gas pressure and temperature as resulting from countless molecular collisions with container walls. Average molecular kinetic energy is proportional to absolute temperature, independent of gas identity.

The change in a system's internal energy equals the heat added to it minus the work it does on its surroundings. It is energy conservation applied to thermal processes, with sign conventions needing care.

A measure of the number of microscopic arrangements consistent with a system's macroscopic state, often described as disorder. In isolated systems it never decreases, giving a direction to spontaneous processes and limiting heat engine efficiency.

The relativistic effect in which a clock moving relative to an observer ticks more slowly as measured by that observer. The effect grows with relative speed and becomes appreciable only near the speed of light.

The principle that mass and energy are interchangeable, with a rest mass corresponding to an energy equal to mass times the speed of light squared. It explains energy release in nuclear reactions and particle annihilation.

The emission of electrons from a metal surface struck by light above a threshold frequency. Its instant onset and frequency dependence, unexplained by classical waves, supported the idea that light arrives in discrete quanta.

The wavelength associated with a particle, equal to Planck's constant divided by its momentum. It explains electron diffraction and why wave behaviour is noticeable only for very small, slow-moving objects.

The time required for half the nuclei in a radioactive sample to decay, a constant characteristic of each isotope. After n half-lives the remaining fraction is one half raised to the power n.

Evaluation conducted during instruction to reveal what learners currently understand and to guide immediate teaching adjustments. It is typically low-stakes and feedback-focused, contrasting with summative grading of final achievement.

Evaluation carried out at the end of a unit or course to judge overall achievement against standards. Results are usually graded or certified and serve reporting purposes rather than shaping ongoing instruction.

A deliberately designed question or demonstration that exposes a common incorrect prior idea, such as the belief that heavier objects always fall faster. Confronting the conflict prepares students to accept the accepted physical explanation.

A scoring guide listing criteria and performance levels used to judge student work consistently. A clear rubric communicates expectations in advance and reduces subjectivity when several graders assess laboratory reports or projects.

A practical activity in which students pose or refine a question, design a procedure, collect and analyse data, and justify conclusions. It develops investigation skills rather than merely confirming a stated result.

A documented set of procedures covering hazard identification, equipment handling, emergency response, and supervision duties for practical work. It should be reviewed before each activity and aligned with local regulations and institutional policy.

Wearable gear such as goggles, gloves, and lab coats that reduces exposure to chemical, thermal, or mechanical hazards. It is the last line of defence and supplements, rather than replaces, engineering controls and safe practice.