Edexcel International GCSE Physics - Unit 1: Forces and Motion Vocabulary

Vocabulary flashcards covering key terms, definitions, principles, and equations from Unit 1: Forces and Motion.

Average Speed

The total distance moved ($s$) divided by the total time taken ($t$), calculated using $v = \frac{s}{t}$.

Instantaneous Speed

The speed of an object measured at a specific instant in time, as indicated by a vehicle speedometer.

Displacement

The distance travelled in a particular specified direction from a starting point.

Vector Quantity

A physical quantity that has both magnitude (size) and a specific direction, such as displacement, velocity, force, or acceleration.

Scalar Quantity

A physical quantity that has magnitude (size) only and no direction, such as distance, speed, mass, or time.

Velocity

The speed of an object in a particular specified direction, defined as the rate of change of displacement.

Acceleration

The rate at which an object changes its velocity, calculated using $a = \frac{v - u}{t}$.

Deceleration

A negative acceleration that occurs when an object slows down, resulting in a final velocity smaller than its initial velocity.

Uniform Acceleration

Motion in which the rate of increase of velocity remains steady or constant over time.

Gradient of a Distance-Time Graph

The slope of a distance-time graph line, which represents the speed (or velocity) of the object.

Gradient of a Velocity-Time Graph

The slope of a velocity-time graph line, which represents the acceleration of the object.

Area Under a Velocity-Time Graph

The area beneath a velocity-time graph line, which represents the total distance travelled (displacement) by an object.

Newton ($N$)

The unit of force; one newton is the force needed to make a mass of $1\,kg$ accelerate at $1\,m/s^2$.

Friction

The force that opposes motion between surfaces in contact or through fluids, converting kinetic energy into thermal energy.

Normal Reaction Force

The upward supporting force exerted by a surface on an object perpendicular ($90^\circ$) to the surface.

Air Resistance (Drag)

A frictional force exerted by air (or a fluid) opposing the movement of an object passing through it.

Upthrust

The upward push force exerted by a surrounding fluid (air or liquid) on an object.

Resultant Force (Unbalanced Force)

The single overall force produced when all individual forces acting on an object are combined, taking their directions into account.

Hooke's Law

The principle stating that the extension of a spring or wire is directly proportional to the applied load force, provided the limit of proportionality is not exceeded.

Limit of Proportionality

The point beyond which the extension of a stretched material is no longer directly proportional to the applied load force.

Elastic Limit

The maximum force or extension up to which a stretched material will return to its original length when the force is removed.

Elastic Behaviour

The ability of a material to recover its original shape after the forces causing deformation have been removed.

Plastic Behaviour

The permanent deformation of a material such that it fails to return to its original shape or length when the applied force is removed.

Stopping Distance

The total distance travelled by a vehicle from the moment the driver spots a hazard until coming to a complete stop, calculated as thinking distance plus 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 from the moment the brakes are applied until the vehicle comes to a complete stop.

Weight

The downward gravitational force acting on an object, calculated using $W = m \times g$.

Gravitational Field Strength ($g$)

The force exerted by gravity per kilogram of mass, measured in $N/kg$ (taken as approximately $10\,N/kg$ on Earth).

Terminal Velocity

The constant maximum speed reached by a falling object when the upward drag force equals its downward weight force, resulting in zero unbalanced force.

Momentum

A measure of how difficult it is to stop a moving mass, calculated using momentum $p = m \times v$.

Conservation of Momentum

The principle stating that the total momentum before a collision or explosion is equal to the total momentum afterwards, provided no external forces act.

Newton's Third Law

The law stating that for every action force there is an equal and opposite reaction force acting on a different body.

Moment of a Force

The turning effect of a force about a pivot, calculated as force multiplied by the perpendicular distance from the line of action to the pivot.

Principle of Moments

The condition for balance stating that the sum of anticlockwise moments about a pivot equals the sum of clockwise moments about the same pivot.

Centre of Gravity

The single point through which the entire weight force of an object appears to act.