Combined Physics: Motion & Forces

Comprehensive vocabulary flashcards covering fundamental definitions, equations, units, and principles from the Motion & Forces unit of GCSE Physics.

Magnitude

The size or numerical value of a physical quantity.

Scalar Quantity

A physical quantity that is completely described by its magnitude (size) only, possessing no direction.

Vector Quantity

A physical quantity that is completely described by both a magnitude (size) and a direction.

Distance

The magnitude of displacement between two positions; a scalar quantity that measures how far an object has moved without regard to direction.

Distance Travelled

The total length of the path taken between two positions; a scalar quantity.

Displacement

The distance moved in a straight line, in a given direction, from the starting position; a vector quantity.

Resultant Vector

A single vector quantity that is equivalent to the combined effect of two or more component vectors acting at the same point.

Tip-to-Tail Diagram

A graphical method used to find a resultant vector by linking component vectors head to tail.

Speed

The rate of change of distance travelled; a scalar quantity measured in metres per second ($\text{m/s}$).

Instantaneous Speed

The speed of an object measured at one specific moment during a journey.

Average Speed

The total distance travelled divided by the total time taken for an entire journey ($\text{average speed} = \frac{\text{total distance}}{\text{time taken}}$).

Velocity

The rate of change of displacement; a vector quantity representing the speed of an object in a specific direction.

Acceleration

The rate of change of velocity over time ($a = \frac{v - u}{t}$), measured in metres per second squared ($\text{m/s}^2$).

Deceleration

A negative acceleration that occurs when an object is slowing down over time.

Force

A push or pull that acts on an object due to an interaction with another object, measured in newtons ($\text{N}$).

Newton-meter

A calibrated spring balance used to measure force directly in newtons ($\text{N}$).

Contact Force

A force that acts only when the interacting objects are physically touching.

Non-contact Force

A force that acts at a distance without physical contact between objects, operating through a field.

Friction

A contact force that opposes the motion between two surfaces in contact rubbing against each other.

Air Resistance

A type of frictional drag force that opposes the motion of an object moving through air.

Tension

A pulling contact force produced in a connected length (such as a string, cable, or rope) when a force is applied to it.

Normal Reaction Force

A contact force pushing upward perpendicular to a supporting surface when an object rests upon it.

Gravitational Force

An attractive non-contact force experienced between objects that possess mass.

Electrostatic Force

A non-contact force experienced between electrically charged bodies, which can be attractive or repulsive.

Magnetic Force

A non-contact force experienced between magnetic poles, which can be attractive or repulsive.

Free-Body Diagram

A diagram modelling all individual forces acting upon an isolated body, represented by scaled, directed, and labelled arrows.

Resultant Force

The single overall net force produced by combining all individual forces acting on an object as vectors.

Balanced Forces

Forces acting on an object in opposite directions that are equal in size, resulting in a resultant force of zero.

Unbalanced Forces

Forces acting on an object that do not cancel out completely, producing a non-zero resultant force.

Equilibrium

A state in which the vector sum of all forces acting on an object is zero, resulting in balanced forces.

Newton's First Law

The law stating that an object remains at rest or continues to move with a constant velocity unless acted upon by a non-zero 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 ($F = ma$).

Newton's Third Law

The law stating that when two bodies interact, they exert equal and opposite forces of the same type on each other (action-reaction pairs).

Centripetal Force

The resultant perpendicular force acting toward the centre of a circle required to keep an object in uniform circular motion.

Mass

The quantity of matter contained within a physical body; a scalar quantity measured in kilograms ($\text{kg}$).

Weight

The downward gravitational force acting on an object's mass ($W = mg$), measured in newtons ($\text{N}$).

Gravitational Field Strength

The force of gravity per unit mass exerted at a specific location, measured in newtons per kilogram ($\text{N/kg}$) or $\text{m/s}^2$.

Centre of Mass

The single point through which an object's entire weight is considered to act.

Inertia

The natural tendency of an object to resist any change in its state of rest or uniform motion.

Inertial Mass

A measure of how difficult it is to change an object's velocity, defined as the ratio of applied force to acceleration ($m = \frac{F}{a}$).

Terminal Velocity

The constant maximum velocity reached by a falling object when the upward drag force balances the downward weight force, resulting in zero acceleration.

Momentum

The product of an object's mass and its velocity ($p = mv$); a vector quantity measured in kilogram metres per second ($\text{kg}\,\text{m/s}$).

Conservation of Momentum

The principle stating that the total momentum of a closed system before an interaction or collision equals the total momentum after it, in the absence of external forces.

Stopping Distance

The total distance a vehicle covers from the moment a hazard is spotted until it halts completely; the sum of thinking distance and braking distance.

Thinking Distance

The distance travelled by a vehicle during the driver's reaction time, before the brakes are applied.

Braking Distance

The distance travelled by a vehicle while the braking system acts to bring it to a stop.

Reaction Time

The time duration taken by an observer to detect and respond to an external stimulus.

Crumple Zone

A vehicle safety structure designed to collapse during an impact, increasing deceleration time and reducing the resultant impact force on passengers.