ETEA Engineering Test key terms

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, written as F = ma when mass stays constant.

In an isolated system with no external net force, the total momentum of all interacting bodies stays the same before and after a collision or explosion.

The net work done on an object by all forces together equals the change in its kinetic energy, so work can be calculated as final minus initial kinetic energy.

The ratio of charge stored on a conductor to the potential difference across it, measured in farads; it depends on plate area, plate separation, and the dielectric between the plates.

For a conductor kept at constant temperature, current is directly proportional to potential difference, giving V = IR, where R is the resistance measured in ohms.

When light travelling in a denser medium strikes a boundary at an angle beyond the critical angle, it is completely reflected back into that medium instead of refracting out.

The change in the observed frequency of a wave when the source, the observer, or both move relative to the medium that carries the wave.

Oscillation in which the restoring force is proportional to displacement from equilibrium and directed toward it, producing sinusoidal motion with a constant period.

Emission of electrons from a metal surface when light above a threshold frequency strikes it, showing that light delivers its energy in discrete quanta rather than continuously.

The time required for half the nuclei in a radioactive sample to decay, a constant characteristic of each isotope that is independent of sample size and initial amount.

Two-dimensional motion of an object launched into the air and moving under gravity alone, with constant horizontal velocity and uniformly accelerated vertical motion.

The number of moles of solute dissolved in one litre of solution, expressed in mol/L; it changes slightly with temperature because solution volume expands on heating.

When a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, it shifts in the direction that partly opposes that disturbance.

A bookkeeping charge assigned to an atom in a compound by assuming bonding electrons belong to the more electronegative atom; it tracks how electrons are rearranged.

A measure of hydrogen ion concentration in a solution, defined as the negative logarithm of that concentration; values below 7 indicate an acidic solution.

A chemical reaction that releases energy to the surroundings, usually as heat, so the products have lower enthalpy than the reactants and the mixture warms up.

Atoms of the same element with equal numbers of protons but different numbers of neutrons, giving them the same chemical behaviour and different mass numbers.

The mixing of atomic orbitals of similar energy to form new equivalent orbitals that explain observed molecular shapes and bond angles, such as sp3 tetrahedral geometry.

An electrochemical device that converts the chemical energy of a spontaneous redox reaction into electrical energy, with oxidation at the anode and reduction at the cathode.

The relation PV = nRT linking pressure, volume, amount in moles, and absolute temperature of a gas whose molecules are assumed to have negligible volume and no attractions.

The simplest whole-number ratio of the atoms of each element present in a compound, which may be a multiple of the actual molecular formula.

A solution that resists a large change in pH when small amounts of strong acid or base are added, typically containing a weak acid together with its conjugate base.

The value a function's output approaches as the input approaches a specified point, whether or not the function is actually defined at that point.

The instantaneous rate of change of a function with respect to a variable, defined as the limit of a difference quotient; geometrically it gives the slope of the tangent line.

The limit of a sum of areas of thin rectangles between two bounds, interpreted as the signed area under a curve over that interval.

A selection of items from a larger set in which the order of choice does not matter; the count equals n factorial divided by k factorial times (n - k) factorial.

A sequence in which each term after the first is obtained by adding a fixed constant difference to the previous term, such as 3, 7, 11, 15.

The probability that event A occurs given that event B has already occurred, computed as P(A and B) divided by P(B) when P(B) is not zero.

A formula that expands (a + b) raised to the power n as a sum of terms containing binomial coefficients, letting you find one term without expanding everything.

The number obtained by reversing the sign of the imaginary part, so the conjugate of a + bi is a - bi; their product is the real number a squared plus b squared.

A scalar obtained from two vectors by multiplying corresponding components and adding the results; it also equals the product of their magnitudes and the cosine of the angle between them.

The complete set of input values for which a function is defined and gives a real output, excluding values that cause division by zero or a negative square root.

The grammatical rule that a verb must match its subject in number and person, so a singular subject takes a singular verb form and a plural subject takes a plural one.

A sentence construction in which the receiver of an action becomes the grammatical subject, formed with a form of the verb 'be' plus the past participle.

A word that has nearly the same meaning as another word in a particular context, such as 'quick' and 'fast', or 'begin' and 'start'.

An expression whose meaning cannot be worked out from the literal meanings of its individual words, such as 'break the ice' or 'under the weather'.

A subordinate clause that describes or identifies a noun, usually introduced by who, which, that, whose, or where, as in 'the book that I lost'.

A word placed before a noun or pronoun to show its relation in time, place, or direction to another element, such as in, on, under, or after.