NYSTCE Physics key terms

A factor that an experimenter deliberately holds constant across all trials so that any change in the outcome can be attributed to the manipulated variable rather than to an unintended influence.

The digits in a measured value that carry meaningful information about its precision, consisting of all certain digits plus one final estimated digit; they govern how a calculated result should be rounded.

An estimate of the range within which the true value of a measured quantity probably lies, reflecting limits of the instrument, the technique, and random or systematic error.

The vector change in an object's position, specified by magnitude and direction from the starting point to the ending point; it does not depend on the path followed.

The rate at which velocity changes with time, a vector quantity that changes when speed changes, direction changes, or both change.

The net force acting on an object equals the product of its mass and its acceleration (F = ma); the acceleration points in the same direction as the net force.

The tendency of an object to resist any change in its state of motion, a property quantified by the object's mass.

A diagram that isolates one object and represents every external force acting on it as an arrow, used to find the net force before applying Newton's laws.

The energy transferred to or from an object when a force acts through a displacement; it equals the force component along the displacement times that displacement.

The principle that when only conservative forces do work on a system, the total of its kinetic and potential energy remains constant even as energy shifts between the two forms.

The product of the average net force on an object and the time interval during which it acts; impulse equals the resulting change in the object's momentum.

The principle that the total momentum of an isolated system stays constant when no net external force acts, so momenta transferred between objects cancel within the system.

The condition in which objects in contact have reached the same temperature, so that no net heat flows between them and their macroscopic properties stop changing.

The lowest attainable temperature, defined as 0 K or approximately −273.15 °C, at which a system's particles have the minimum possible average kinetic energy.

The quantity of heat required to raise the temperature of one kilogram of a substance by one kelvin, a property that determines how quickly a material warms or cools.

The energy absorbed or released by a substance while it changes phase at constant temperature, such as when ice melts or water boils.

The change in a system's internal energy equals the heat added to the system minus the work done by the system, expressing conservation of energy for thermal processes.

A measure of the disorder or of the number of microscopic arrangements available to a system; it increases in any spontaneous process occurring in an isolated system.

The distance between two consecutive corresponding points on a repeating wave, such as from crest to crest, measured along the direction the wave travels.

The number of complete wave cycles that pass a fixed point each second, measured in hertz and equal to the reciprocal of the wave's period.

The principle that when two or more waves meet at a point, the resultant displacement there is the algebraic sum of the displacements each wave would produce alone.

A vibration pattern produced when two waves of equal frequency travel in opposite directions and interfere, creating fixed nodes of no motion and antinodes of maximum motion.

The condition in which a system driven at one of its natural frequencies oscillates with unusually large amplitude because energy is absorbed efficiently from the driving source.

The shift in the frequency or wavelength of a wave detected by an observer because the source and observer are moving relative to each other.

The change in direction of a wave as it crosses into a medium where its speed differs, caused by the resulting change in wavelength at the boundary.

The force per unit positive charge at a point in space, a vector that points in the direction a positive test charge placed there would be pushed.

The electric potential energy per unit charge at a point in a field, measured in volts; differences in potential drive charge flow through circuits.

The ratio of the charge stored on one conductor of a capacitor to the potential difference between the conductors, measured in farads.

The relationship stating that the current through a metallic conductor is directly proportional to the potential difference across it, with resistance as the constant of proportionality (V = IR).

A vector field surrounding magnets and moving electric charges that exerts forces on other moving charges and on magnetic materials, measured in teslas.

The production of an electromotive force, and often a current, in a conductor when the magnetic flux through it changes with time.

The rule that an induced current flows in the direction whose own magnetic field opposes the change in flux that produced it, a consequence of energy conservation.

The relativistic effect in which a clock moving relative to an observer runs slower than a clock at rest with that observer, becoming pronounced near the speed of light.

A discrete packet of electromagnetic energy whose energy equals Planck's constant multiplied by the radiation's frequency; light is composed of such quanta.

The ejection of electrons from a metal surface when light above a threshold frequency strikes it, evidence that light delivers energy in particle-like packets.

The minimum energy needed to remove an electron from the surface of a particular metal; it determines the threshold frequency for the photoelectric effect.

The wavelength associated with a moving particle in the quantum model, equal to Planck's constant divided by the particle's momentum, which explains electron diffraction.

The time required for half of the radioactive nuclei in a sample to decay, a characteristic constant of each isotope that is unaffected by temperature or chemical state.

The difference between the mass of a nucleus and the sum of the masses of its separate nucleons, equivalent through E = mc² to the nucleus's binding energy.

The principle that light and matter show wave-like behavior in some experiments and particle-like behavior in others, depending on how they are observed.