physics defintions 2026

Speed

The rate of change of velocity per second. It

Vector quantity

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

Scalar quantity

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

Acceleration

The rate at which an object changes its velocity per unit of time. It is a vector quantity. Formula: $a = \frac{\Delta v}{t}$. Unit: metres per second squared ($\text{m/s}^2$).

Force

A push or pull that can cause an object to accelerate. It is a vector quantity. Formula: $F = m \times a$. Unit: newton ($\text{N}$), where $1\,\text{N} = 1\,\text{kg}\cdot\text{m/s}^2$.

Mass

The amount of matter in an object. It is a scalar quantity measured in kilograms ($\text{kg}$) and does not change depending on location.

Weight

The force of gravity acting on an object's mass. It is a vector quantity measured in newtons ($\text{N}$). Formula: $W = m \times g$. It changes depending on the strength of the gravitational field.

Friction

A force that opposes the relative motion between two surfaces in contact. It slows down moving objects, can prevent stationary objects from moving, and can cause energy to be lost as heat.

Pressure

The amount of force applied per unit area. Formula: $P = \frac{F}{A}$. Unit: pascal ($\text{Pa}$), where $1\,\text{Pa} = 1\,\text{N/m}^2$.

Gravitational potential energy (GPE)

The energy an object possesses due to its position in a gravitational field, usually relative to the Earth's surface. Formula: $E_p = m \times g \times h$. Unit: joule ($\text{J}$).

Kinetic energy

The energy an object possesses due to its motion. Formula: $E_k = \frac{1}{2} \times m \times v^2$. Unit: joule ($\text{J}$).

Work

The amount of force used to move an object over a distance in the direction of the force. Formula: $W = F \times d$. Unit: joule ($\text{J}$).

Power

The rate at which work is done or energy is transferred. Formula: $P = \frac{W}{t} = \frac{E}{t}$. Unit: watt ($\text{W}$), where $1\,\text{W} = 1\,\text{J/s}$.

Electrical conductor

A material that allows electric charge (current) to flow through it easily (e.g., metals like copper and aluminium).

Electrical insulator

A material that does not allow electric charge to flow through it easily (e.g., rubber, plastic, glass).

Electrical resistance

A measure of how much a material opposes the flow of electric current. Formula: $R = \frac{V}{I}$. Unit: ohm ($\Omega$).

Electric current

The amount of electric charge that passes through a specific point in a wire or component per second. Formula: $I = \frac{Q}{t}$ or $I = \frac{V}{R}$. Unit: ampere ($\text{A}$).

Voltage

The electric potential energy per unit charge, providing the push or driving force to move electric charge around a closed circuit. Formula: $V = \frac{W}{Q}$ or $V = I \times R$. Unit: volt ($\text{V}$).