IGCSE Physics: Motion, Forces, Energy, and Measurement Vocabulary

Vocabulary flashcards defining fundamental physics terms, equations, and principles from the lecture notes.

Velocity

The speed of an object in a given direction, defined as a vector quantity possessing both magnitude and direction.

Acceleration

The rate of change of velocity per unit time, represented by the formula $a = \frac{\text{Δ}v}{\text{Δ}t}$ and measured in $\text{m/s}^2$.

Acceleration of Freefall

The constant acceleration experienced by an object falling freely under gravity near Earth's surface, denoted by $g$ and equal to $9.8\,\text{m/s}^2$.

Mass

A measure of the quantity of matter in an object, which resists changes in motion and is measured in kilograms ($\text{kg}$).

Weight

The gravitational force acting on an object with mass, calculated using $W = mg$ and measured in newtons ($\text{N}$).

Density

The mass per unit volume of a substance, defined by the formula $\rho = \frac{m}{V}$ and measured in $\text{kg/m}^3$ or $\text{g/cm}^3$.

Upthrust

An upward force exerted by a fluid on an object submerged within it, acting opposite to the weight force of the object.

Resultant Force

A single net force that represents the combined vector sum and overall effect of all individual forces acting on an object.

Scalar Quantity

A physical quantity that has magnitude only and no specific direction (e.g., speed, mass, energy, distance).

Vector Quantity

A physical quantity that possesses both magnitude and direction (e.g., velocity, acceleration, weight, force, displacement).

Displacement

The distance measured along a straight line from an object's starting point to its finishing point, including the specified direction.

Drag

A resistive frictional force opposing the motion of an object moving through a fluid (gas or liquid), such as air resistance.

Hooke's Law

The principle stating that the extension $x$ of a spring is directly proportional to the applied force $F$ ($F = kx$) provided the limit of proportionality is not exceeded.

Newton's First Law of Motion

States that an object will remain at rest or continue moving with a constant velocity unless acted upon by a non-zero resultant force.

Newton's Second Law of Motion

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

Centre of Gravity

The point through which the entire weight force of an object is considered to act.

Moment

The turning effect produced by a force acting about a fixed pivot, calculated as the force multiplied by the perpendicular distance from the pivot.

Principle of Moments

States that for a balanced object in rotational equilibrium, the sum of the total clockwise moments about a pivot equals the sum of the total anticlockwise moments about that pivot.

Equilibrium

A state of balance where an object experiences zero resultant force and zero resultant turning moment.

Pressure

The force exerted per unit area perpendicular to a surface, defined by the formula $p = \frac{F}{A}$.

System

An object or a group of objects being studied to analyze changes in energy stores and energy transfers.

Principle of Conservation of Energy

States that energy cannot be created or destroyed, only transferred from one store to another, so the total energy in a closed system remains constant.

Kinetic Energy Store

The energy stored in an object due to its motion, calculated using the equation $E_k = \frac{1}{2}mv^2$.

Gravitational Potential Energy Store

The energy stored in an object due to its height position within a gravitational field, calculated as $\text{Δ}E_p = mg\text{Δ}h$.

Work Done

The amount of energy transferred when a force moves an object through a distance, defined as $W = Fd$.

Power

The rate of doing work or transferring energy per unit time, given by $P = \frac{W}{t}$ or $P = \frac{E}{t}$ and measured in Watts ($\text{W}$).

Efficiency

The ratio of useful energy (or power) output to total energy (or power) input, expressed as a percentage.

Renewable Energy Resource

An energy resource that is replenished naturally at the same rate as, or faster than, it is consumed (e.g., solar, wind, hydro, geothermal).

Nuclear Fission

The nuclear process in which a large, heavy atomic nucleus splits into smaller daughter nuclei, releasing neutrons and energy.

Nuclear Fusion

The nuclear process in which two smaller atomic nuclei combine under extreme temperature and pressure to form a larger nucleus, releasing energy.

Fiducial Marker

A fixed visual reference point (such as a line or dot) placed at the equilibrium position of an oscillating system to reduce timing measurement errors.