BAF Officer Cadet key terms

The rate at which an object changes its position in a stated direction, measured as displacement divided by time. It differs from speed because it includes direction, so it is a vector quantity.

The rate at which velocity changes with time, whether the object speeds up, slows down, or changes direction. It is measured in metres per second squared and is a vector quantity.

A rule stating that the net force on an object equals its mass multiplied by its acceleration. It explains why a heavier object needs a larger force to gain the same acceleration.

The tendency of an object to resist any change in its state of rest or uniform motion. Mass is the measure of inertia, so a more massive body is harder to start or stop moving.

The product of an object's mass and its velocity, describing how hard it is to stop the object. In a closed system the total momentum before and after a collision stays constant.

The energy transferred when a force moves an object through a distance in the direction of the force. It is calculated as force times displacement and measured in joules.

The rate at which work is done or energy is transferred, calculated as work divided by time. It is measured in watts, where one watt equals one joule per second.

The energy an object possesses because of its motion, equal to half its mass times the square of its velocity. Doubling the speed gives four times the kinetic energy.

Scalars are quantities with magnitude only, such as mass, time and temperature. Vectors have both magnitude and direction, such as displacement, velocity and force, and are added using direction-aware rules.

A relationship stating that the current through a conductor is directly proportional to the voltage across it, provided temperature stays constant. It is written as voltage equals current times resistance.

The opposition a material offers to the flow of electric current, measured in ohms. It depends on the material, its length, its cross-sectional area and its temperature.

The rate of flow of electric charge past a point in a circuit, measured in amperes. One ampere equals one coulomb of charge passing a point each second.

The bending of light as it passes from one transparent medium into another of different optical density, caused by a change in its speed. It explains why a stick looks bent in water.

The bouncing back of light when it strikes a surface. The angle of incidence equals the angle of reflection, and both angles are measured from the normal to the surface.

A curved piece of transparent material that bends light to converge or diverge it. A convex lens converges light and can form a real image, while a concave lens diverges light.

The time taken for half the atoms of a radioactive sample to decay. It is constant for a given isotope and is unaffected by temperature, pressure or chemical state.

The spontaneous emission of particles or radiation from unstable atomic nuclei as they change into more stable forms. Alpha, beta and gamma emissions are the common types.

One of two or more forms of the same element whose atoms have the same number of protons but different numbers of neutrons. Isotopes share chemical properties but may differ in mass and stability.

The number of protons in the nucleus of an atom, which identifies the element. In a neutral atom it also equals the number of electrons orbiting the nucleus.

The amount of a substance containing as many particles as there are atoms in twelve grams of carbon-12. That number, Avogadro's number, is about 6.02 times ten to the power twenty-three.

The mass of one mole of a substance, expressed in grams per mole. It is found by adding the relative atomic masses of all atoms in the chemical formula.

The simplest whole-number ratio of atoms of each element present in a compound. It may differ from the molecular formula, which gives the actual number of atoms per molecule.

A measure of solution concentration equal to the number of moles of solute dissolved in one litre of solution. It is commonly written with the unit moles per litre.

An acid donates hydrogen ions in solution, while a base accepts them or releases hydroxide ions. Their reaction, called neutralisation, produces a salt and water.

A scale from zero to fourteen measuring the acidity or alkalinity of a solution based on hydrogen ion concentration. Values below seven are acidic, seven is neutral and above seven is basic.

Oxidation is the loss of electrons by a substance, while reduction is the gain of electrons. The two always occur together in a redox reaction, so one species is oxidised as another is reduced.

The process by which green plants use sunlight, water and carbon dioxide to make glucose and release oxygen. It takes place mainly in the chloroplasts and is powered by the pigment chlorophyll.

The controlled release of energy from glucose inside living cells. Aerobic respiration uses oxygen and yields much more energy than anaerobic respiration, which produces lactic acid or ethanol.

A protein that speeds up a specific biochemical reaction by lowering its activation energy. Enzymes are sensitive to temperature and pH, and each usually acts on one particular substrate.

A type of cell division that produces two daughter cells genetically identical to the parent cell. It is used for growth, repair and replacement of body cells in multicellular organisms.

A type of cell division that halves the chromosome number and produces four genetically different gametes. It creates variation through crossing over and independent assortment of chromosomes.

A section of a DNA molecule that carries the instructions for making a particular protein or trait. Genes are passed from parents to offspring and are located on chromosomes.

A ratio compares two quantities of the same kind, while a proportion states that two ratios are equal. Proportions are solved by cross-multiplication to find an unknown value.

A way of expressing a number as a fraction of one hundred. It is used to compare quantities and to calculate increases, decreases, discounts and interest.

Interest calculated only on the original principal for the whole period, using the formula principal times rate times time divided by one hundred. It does not earn interest on interest.

The sum of a set of values divided by the number of values, also called the arithmetic mean. It gives a single value representing the centre of the data.

A form of logical reasoning in which a conclusion is drawn from two or more given statements assumed to be true. Validity depends on the form of the argument, not on real-world facts.

Reasoning that moves from general statements to a specific conclusion that must follow if the premises are true. It guarantees the conclusion rather than merely making it probable.

A statement offered as evidence or a starting assumption in an argument. The strength of a conclusion depends on whether the premises are true and properly connected.

A word whose meaning is opposite to that of another word, such as hot and cold. Recognising antonyms helps in vocabulary questions and in understanding contrast within a sentence.

A word that has the same or nearly the same meaning as another word, such as begin and start. Choosing the right synonym depends on context, tone and level of formality.

A fixed expression whose meaning cannot be worked out from the individual words, such as a piece of cake for something easy. Idioms are learned as whole units.

In active voice the subject performs the action, as in the boy kicked the ball. In passive voice the object becomes the subject and the verb uses a form of be with a past participle.

Direct speech reports a person's exact words inside quotation marks, while indirect speech reports the meaning without quoting. Indirect speech usually shifts tense, pronouns and time words.

The form of a verb that shows the time of an action, such as present, past or future, and often whether it is continuing or complete. Correct tense keeps a sentence's timeline consistent.

The armed struggle through which Bangladesh gained independence from Pakistan after months of conflict. It followed the 1971 crackdown and ended with the surrender of Pakistani forces on 16 December 1971.

A political and cultural movement in East Pakistan demanding that Bengali be made a state language. Its high point was the police firing on protesters in Dhaka on 21 February 1952.

A set of demands raised in 1966 for greater autonomy for East Pakistan, including separate fiscal policy and a federal system. It became a key step towards the independence struggle.

The provisional government of Bangladesh formed in April 1971 after the declaration of independence. It organised the liberation struggle and was sworn in at Mujibnagar in Meherpur district.

The 1905 division of the province of Bengal by the British, which separated its eastern and western parts. It was withdrawn in 1911 after widespread protest and the Swadeshi movement.

An international organisation founded in 1945 to maintain peace and security and to promote cooperation among states. Bangladesh became a member in 1974.

The South Asian Association for Regional Cooperation, formed in 1985 to promote cooperation among South Asian countries. Its secretariat is located in Kathmandu, Nepal.

A grouping of states that chose not to align formally with either major power bloc during the Cold War. It was founded in 1961 at a summit in Belgrade.