CAIE IGCSE Physics (0625) Vocabulary Flashcards

Vocabulary practice flashcards covering fundamental physical quantities, mechanics, energy stores, momentum, pressure, and thermal physics from CAIE IGCSE Physics.

SI System

A set of units, known as the Système International d’Unités, used for standard measurements across many countries.

Scalar quantity

A physical quantity that has magnitude (size) only, such as distance, speed, time, mass, pressure, energy, and temperature.

Vector quantity

A physical quantity described by both magnitude and direction, such as force, gravitational field strength, weight, velocity, acceleration, and momentum.

Distance

The total length a body travels between two points, which is a scalar quantity.

Displacement

The distance moved in a specified direction relative to a starting point, which is a vector quantity.

Speed

The distance travelled per unit time by an object.

Velocity

The rate of change of displacement per unit time, representing speed in a specified direction.

Acceleration

The change in velocity per unit time of an object.

Acceleration of free fall

The uniform acceleration experienced by all bodies falling freely under gravity when air resistance is negligible, denoted as $g$ and equal to about $9.8\,m/s^2$ on Earth.

Terminal velocity

The maximum constant velocity reached by a falling object when air resistance equals its weight, resulting in zero net acceleration.

Mass

A measure of the quantity of matter in an object at rest relative to an observer, measured in kilograms ($\text{kg}$).

Weight

The gravitational force acting on an object that has mass, measured in newtons ($\text{N}$).

Gravitational field strength

The force per unit mass acting on an object, which on Earth's surface is equal to $9.8\,N/kg$.

Density

The measure of mass per unit volume of a substance, given by the formula $\rho = \frac{m}{V}$.

Spring constant

The force needed to cause a unit extension in a spring, represented by $k = \frac{F}{x}$.

Resultant force

A single force that has the same effect on an object as all individual forces acting together.

Newton’s First Law

The principle that an object remains at rest or continues to move at a constant speed in a straight line unless acted upon by a resultant force.

Newton’s Second Law

The law stating that the acceleration of an object is directly proportional to the resultant force acting on it and inversely proportional to its mass, expressed as $F = ma$.

Static friction

The frictional force that opposes the starting of motion between surfaces in contact.

Kinetic friction

The frictional force that opposes the motion of surfaces sliding past each other.

Centripetal force

The force directed towards the centre of a circle that causes an object to travel along a curved path.

Moment of a force

The turning effect of a force around a pivot point, calculated as the force multiplied by the perpendicular distance from the pivot ($M = F \times d$).

Principle of moments

The rule stating that for a beam in equilibrium, the sum of clockwise moments about any point equals the sum of anticlockwise moments about the same point.

Centre of gravity

The single point through which the entire weight of an object acts.

Momentum

A vector quantity defined as the product of an object's mass and its velocity ($p = mv$).

Conservation of momentum

The law stating that the total momentum of a closed system remains constant provided no external forces act on it.

Impulse

The change in momentum of an object caused by a force acting over a period of time ($J = F \Delta t = \Delta p$).

Kinetic energy

The energy an object possesses due to its motion, calculated using $E_k = \frac{1}{2} m v^2$.

Gravitational potential energy

The energy an object possesses due to its position relative to a reference point in a gravitational field, calculated as $E_p = mgh$.

Work

The energy transferred when a force displaces an object through a distance in the direction of the force ($W = F \cdot d$).

Power

The work done or energy transferred per unit time, measured in watts ($\text{W}$).

Pressure

The force per unit area acting perpendicular to a surface, defined as $p = \frac{F}{A}$.

Brownian motion

The random motion of small particles suspended in a fluid, caused by collisions with smaller, rapidly moving particles.

Absolute zero

The lowest possible temperature ( $-273\,^\circ\text{C}$ or $0\,\text{K}$) at which all particle motion ceases.

Specific heat capacity

The energy required per unit mass to increase the temperature of a substance by $1\,^\circ\text{C}$, expressed as $c = \frac{\Delta E}{m \Delta \theta}$.

Conduction

The transfer of thermal energy through matter from hot to cold regions without movement of the matter as a whole.

Convection

The transfer of thermal energy in fluids due to the bulk movement of the fluid caused by temperature and density variations.

Radiation

The transfer of thermal energy via electromagnetic waves, which can occur across a vacuum.