Physics Concepts and Vocabulary

A comprehensive vocabulary set covering key physics terms ranging from motion and forces to circular motion and gravity, based on the provided curriculum notes.

Accelerate

When something changes its velocity

Acceleration

The rate of change of velocity of a moving object. Can result from a change in speed and/or a change in direction

Acceleration due to gravity

On surface of earth, value is $9.8\,ms^{-2}$; increases nearer the poles, decreases with altitude and depth inside the earth

Amplitude (of an oscillation)

The maximum displacement of a body from the equilibrium position during an oscillatory motion

Angular Acceleration

The rate of change of angular velocity of a rotating body.

Angular Displacement

The angle described at the center of the circle by a moving body along a circular path

Angular frequency

Frequency expressed in radians per second

Angular momentum

$\text{Mass} \times \text{angular velocity}$ for an object undergoing circular motion

Angular Velocity

The rate of change of angular displacement of a rotating body.

Average velocity

Total displacement divided by the total time taken

Axis

The imaginary line about which a planet or other object rotates

Balanced Forces

When a number of forces act on a body, and the resultant force is zero

Centripetal force

Force required to keep an object moving in a circle

Change in momentum

Momentum after minus momentum before

Change in velocity

Velocity after minus velocity before

Circular Motion

The motion of a body along a circular path

Circular orbit

An orbit that is circular

Collision

Objects hitting each other

Combined mass

Sum of masses involved

Conservation of Energy

When energy is transformed from one type of energy into another, the total energy before and after are always the same

Conservation of mass

Mass, including single atoms, is neither created nor destroyed in a chemical reaction

Conservation of momentum

The total momentum of a group of a closed system remains constant in the absence of external forces

Constant speed

Speed that stays the same

Dampen

Any effect causing loss of energy during SHM e.g. Air resistance

Deceleration

Negative acceleration

Displacement

The change in the position of an object in a particular direction

Distance

The actual length of the path traveled by a body irrespective of the direction

Elastic collision

Collision where kinetic energy is conserved

Equations of motion

Set of formulas used to describe motion mathematically

Equilibrium Position

Where the mass wants to be in simple harmonic motion

Escape Velocity

The minimum velocity with which an object must be thrown upwards so as to escape into space

Extension of a spring

How much a spring is extended (stretched or compressed) compared to its natural length

Force

Forces change the state of rest or of uniform motion, the direction of motion, or the shape and size of a body

Force of gravitation

The force with which two objects attract each other because of their masses

Free fall

The motion of a body towards the earth when no other force except weight acts on it

Friction

The force that resists the motion of one surface relative to another with which it is in contact

Gravitational constant G

The Universal Gravitational constant G which appears in the equation for Newton's law of gravitation

Gravitational Field Strength

Strength of the gravitational field at a particular point - known locally as g

Gravitational Potential Energy

Energy stored in a gravitational field when an object is moved vertically upwards

Gravity

Force of attraction between two objects due to their mass

Horizontal circle

A circle that involves no gain or loss in gravitational potential energy

Impulse

Change in momentum caused by an external force

Inelastic collision

Collision where kinetic energy is not conserved (some energy is converted to sound or heat etc.)

Inertia

The property of matter that causes it to resist any change in its state of rest or of uniform motion

Kinetic Energy

Energy possessed by a body by the virtue of its motion

Mass

The quantity of matter contained in a body; it remains the same everywhere

Matter

Anything that occupies space and has mass

Momentum

The product of a body’s mass and velocity

Motion

Manner of how a body moves

Net force

The resulting force after all forces have been added using vectors

Newton

A unit of force defined as $1\,Newton$ force is needed to accelerate a $1\,kg$ mass $1\,ms^{-2}$

Newton's first law of motion

A body continues in a state of rest or of uniform motion in a straight line unless it is acted upon by an external force

Newton's law of gravitation

Force between two particles is proportional to their masses & inversely proportional to the square of the distance between them

Newton's second law of motion

The rate of change of momentum is equal to force OR force acting on a body is equal to the product of its mass and acceleration

Newton's third law of motion

To every action there is an equal and opposite reaction. The action and reaction act on two different bodies simultaneously

Non Uniform Acceleration

When the velocity of a body increases by unequal amounts in equal intervals of time

Non Uniform Speed

When a body travels unequal distances in equal intervals of time

Non Uniform Velocity

Covers unequal distances in equal intervals of time in one direction/ Covers equal distances in equal intervals but changes direction

Origin

Initial position of an object

Oscillatory motion

The to and fro motion of a body about its mean position

Pendulum

A mass (called “Bob”) tied to a piece of string

Period

For a particular vibration, the time for one complete oscillation

Pivot

Point upon which an object turns or rotates

Potential Energy

The energy of a body due to its height or the energy of a body due to its shape

Projectile

An object thrown into space either horizontally and under the action of gravity

Radius

Distance from centre of circle to edge

Range

The horizontal distance traveled by a projectile

Rectilinear Motion

The motion of a body in a straight line

Resonant frequency

The frequency of vibration of an elastic object that depends on the size, composition, and shape of the object

Restoring force

The force which moves an oscillating body back towards its mean position whenever it is displaced

Retardation

Negative acceleration

Revolution

One full circle ($2\pi$)

Rotational Inertia

Measure of the reluctance of an object to change its rotation

Simple harmonic motion

The vibratory motion that occurs when there is a restoring force opposite to and proportional to a displacement

Speed

The distance traveled by a body in one unit of time

Spring constant

Force required to extend or compress a spring by one metre

State of Motion

When a body changes its position with respect to a fixed point

State of Rest

When a body does not change its position with respect to a fixed point

Tangential velocity

Velocity in a perpendicular direction to the centripetal force at a given instant

Tension force

Force in object that opposes them being stretched

Time of flight

The time taken by a projectile from the moment it is thrown until it touches the ground

Torque

Turning force (not applied through the centre of mass)

Unbalanced forces

When a number of forces act on a body and the resultant force is not zero

Uniform Acceleration

When the velocity of a body increases by equal amounts in equal intervals of time

Uniform Circular Motion

The motion of an object in a circular path with uniform speed

Uniform Speed

When a body travels equal distances in equal intervals of time

Uniform Velocity

When a body travels along a straight line in particular direction and covers equal distances in equal intervals of time

Universal Gravitational

$6.67 \times 10^{-11}$ used in the formula for Newton’s Law on universal gravitation

Universal law of gravitation

Every object in the universe is attracted to every other object

Vector addition

Numerically add vectors by use of Pythagoras’s theorem to calculate magnitude and direction

Vector components

A vector (e.g. Force) separated into vertical and horizontal components

Vector diagram

Scale diagram to show magnitude and direction of vectors

Vector Quantity

A quantity, which needs both magnitude and direction to describe it

Velocity

Distance traveled by a body in a particular direction per unit time

Vertical circle

Circular motion where the speed, as well as the direction of the object, is constantly changing

Vertical component

Vector quantities can be separated into two components at $90^{\circ}$ to each other – horizontal and vertical

Weight

The force with which a body is attracted towards the center of the earth

Weightless

Apparent loss of weight of a body in free-fall

Weightlessness

When the apparent weight of a body becomes zero. All objects while falling freely experience this

Work

Work is done when force acting on a body moves it