Edexcel IAL Physics Unit 1 – Mechanics & Materials Vocabulary

A set of vocabulary flashcards covering key definitions for Mechanics (Unit 1.1) and Materials (Unit 1.2) in Edexcel IAL Physics A-level.

Acceleration

The rate of change of velocity.

Acceleration-Time Graph

A plot of acceleration against time; the area under the graph gives the change in velocity and the gradient gives the rate of change of acceleration (jerk).

Centre of Gravity

The single point through which an object’s weight can be considered to act.

Conservation of Energy

Energy cannot be created or destroyed; it can only be transferred from one form to another.

Conservation of Linear Momentum

In the absence of external forces, the total linear momentum of a system before an event equals the total after the event.

Coplanar Vectors

Vectors that lie in the same plane.

Displacement-Time Graph

A plot of displacement against time; the gradient gives velocity and curvature indicates acceleration.

Efficiency

The ratio of useful energy output to total energy input.

Equilibrium

When both the resultant force and resultant moment on an object are zero.

Free-Body Force Diagram

A diagram showing all the forces acting on a single object.

Free-Fall

Motion in which gravity is the only force acting on the object.

Gravitational Field Strength

The force per unit mass experienced by a small test mass placed in the field.

Gravitational Potential Energy

Energy an object possesses because of its position in a gravitational field.

Kinetic Energy

Energy possessed by a moving object; proportional to its mass and the square of its velocity.

Moment of a Force

The product of a force and the perpendicular distance from its line of action to a pivot.

Momentum

The product of an object’s mass and its velocity.

Newton’s First Law of Motion

An object remains at rest or in uniform motion unless acted on by a resultant force.

Newton’s Second Law of Motion

The resultant force on an object equals the rate of change of its momentum (often expressed as F = ma).

Newton’s Third Law of Motion

For every action there is an equal and opposite reaction.

Power

The rate at which energy is transferred or work is done.

Projectile Motion

Motion of an object launched and then acted on only by gravity; analysed in independent horizontal and vertical components.

Scalar Quantity

A quantity that has magnitude only, with no direction (e.g., speed, distance, temperature).

Terminal Velocity

The maximum constant speed of an object when resistive and driving forces are balanced.

Uniformly Accelerated Motion

Motion with constant acceleration, allowing the use of SUVAT equations.

Vector Quantity

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

Velocity-Time Graph

A plot of velocity against time; the gradient gives acceleration and the area under the graph gives displacement.

Weight

The gravitational force acting on an object; equal to mass multiplied by gravitational acceleration.

Work Done

Energy transferred by a force acting over a distance (force × distance).

Breaking Stress

The maximum stress a material can withstand before fracturing.

Compression

The effect of two coplanar forces pushing into an object, usually shortening it.

Density

Mass per unit volume of a material.

Elastic Deformation

Temporary deformation that disappears when the forces are removed; the object returns to its original shape.

Elastic Limit

The maximum stress that can be applied without causing permanent deformation.

Elastic Strain Energy

Energy stored in an object when it is stretched; equal to the work done and the area under a force-extension graph.

Force-Compression Graph

Graph for a compressed spring; the gradient equals the spring constant, and the area under the graph is the work done.

Force-Extension Graph

Graph for a stretched spring; the gradient equals the spring constant, and the area under the graph is the work done.

Hooke’s Law

The extension of an elastic object is directly proportional to the applied force up to the limit of proportionality.

Laminar Flow

Smooth fluid flow in parallel layers with little or no mixing between them.

Limit of Proportionality

The point beyond which stress is no longer proportional to strain and Hooke’s law ceases to apply.

Plastic Deformation

Permanent deformation that remains after the deforming forces are removed.

Stiffness

A measure of how difficult it is to stretch or compress an object (related to its spring constant).

Strain

The ratio of extension to original length; a dimensionless quantity.

Stress

Force acting per unit area; measured in Pascals (Pa).

Stress-Strain Graph

Plot of stress versus strain; its gradient gives the Young modulus.

Tensile Forces

Forces that act to stretch a material, increasing its strain.

Turbulent Flow

Chaotic fluid flow in which layers mix unpredictably.

Upthrust

The upward force exerted by a fluid on an object, equal to the weight of the displaced fluid (Archimedes’ Principle).

Viscosity

A measure of a fluid’s internal friction; it resists flow and is temperature dependent.

Viscous Drag

Resistive force on a sphere moving through laminar fluid; proportional to radius, velocity, and fluid viscosity.

Yield Point

Point on a force-extension graph where a material begins to extend rapidly without additional stress.

Young Modulus

The ratio of stress to strain for a material; a measure of stiffness in Pascals (Pa).