BCECE key terms

An expression showing which base quantities (mass, length, time, etc.) make up a physical quantity, with each raised to a power. Used to check equations and convert units.

The two-dimensional motion of an object thrown into the air, moving under gravity alone. Its horizontal velocity stays constant while vertical velocity changes uniformly.

Motion in a circle at constant speed. Although speed is constant, the direction of velocity changes continuously, so the object accelerates toward the centre.

The net force directed toward the centre of a circular path that keeps an object moving in that circle. Its magnitude equals mass times speed squared divided by radius.

The net work done on an object equals its change in kinetic energy. This links force and displacement to changes in speed without needing time.

In the absence of non-conservative forces like friction, the sum of kinetic and potential energy remains constant. Energy may transform between forms but the total stays fixed.

A measure of an object's resistance to changes in its rotational motion. It depends on mass distribution relative to the axis of rotation.

The turning effect of a force about an axis, calculated as force times perpendicular distance from the axis. It changes angular momentum and causes angular acceleration.

The rotational analogue of linear momentum, equal to moment of inertia times angular velocity. It is conserved when no external torque acts on a system.

An oscillation in which acceleration is proportional to displacement and directed toward the equilibrium position. Its period is independent of amplitude.

A phenomenon where an oscillating system is driven at its natural frequency, causing a large increase in amplitude. It occurs in mechanical, acoustic, and electrical systems.

The change in observed frequency of a wave when the source and observer move relative to each other. It applies to sound, light, and other waves.

When light travels from a denser to a rarer medium at an angle greater than the critical angle, it is completely reflected back. This occurs because refraction is impossible beyond that angle.

The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is exactly 90 degrees. Beyond it, total internal reflection occurs.

The emission of electrons from a metal surface when light of sufficiently high frequency strikes it. It provides evidence that light behaves as particles called photons.

The wavelength associated with a moving particle, equal to Planck's constant divided by the particle's momentum. It demonstrates the wave nature of matter.

The number of particles in one mole of a substance, approximately 6.022 × 10^23 per mole. It connects the microscopic scale of atoms to macroscopic amounts.

A method of counting particles by grouping them into moles, where one mole contains Avogadro's number of entities. It relates mass, number of particles, and volume of gases.

The mass of one mole of a substance, usually expressed in grams per mole. It is numerically equal to the sum of atomic masses in the chemical formula.

The calculation of quantities of reactants and products in a chemical reaction using the balanced equation. It allows prediction of masses, volumes, or moles involved.

The reactant that is completely consumed first in a chemical reaction, limiting the amount of product formed. Other reactants are said to be in excess.

When a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, it shifts to counteract the disturbance and restore equilibrium.

A number that expresses the ratio of product concentrations to reactant concentrations at equilibrium, each raised to the power of their stoichiometric coefficients. It depends on temperature.

A logarithmic scale measuring acidity, defined as the negative logarithm of hydrogen ion concentration. Values below 7 are acidic and above 7 are basic at room temperature.

A solution that resists large changes in pH when small amounts of acid or base are added. It usually contains a weak acid and its conjugate base.

A device that converts chemical energy into electrical energy, or vice versa, through redox reactions. It consists of two electrodes in electrolyte solutions.

The potential difference of an electrode relative to a standard hydrogen electrode, measured under standard conditions. It indicates the tendency of a species to gain or lose electrons.

The mixing of atomic orbitals to form new hybrid orbitals of equal energy, explaining molecular geometry. Common types include sp, sp2, and sp3.

A model predicting the shape of molecules by assuming electron pairs around a central atom repel each other and arrange as far apart as possible.

The number of chemical bonds between a pair of atoms, such as 1 for single, 2 for double, and 3 for triple. It can also be calculated from molecular orbital theory.

The existence of compounds with the same molecular formula but different arrangements of atoms or different spatial orientations, leading to distinct properties.

A property of a molecule that is not superimposable on its mirror image, often due to a carbon atom bonded to four different groups. Such molecules rotate plane-polarized light.

A specific group of atoms within a molecule that is responsible for its characteristic chemical reactions. Examples include hydroxyl, carbonyl, carboxyl, and amino groups.

The value that a function approaches as the input approaches some point. It is fundamental to defining continuity, derivatives, and integrals.

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

The limit of a sum of areas under a curve, representing accumulation. The definite integral gives net area, while the indefinite integral represents a family of antiderivatives.

A property of a function where small changes in input produce small changes in output. Formally, the function has no breaks, jumps, or holes at a point.