Physics A Level Paper 1 inc FM

Angular speed

A measure of the speed of an object's angular rotation. It is equal to the frequency of rotation multiplied by 2𝝅.

Centripetal acceleration

The acceleration of an object moving in circular motion. Any object in circular motion must have an acceleration since the direction of the object, and therefore the velocity of the object, is constantly changing.

Centripetal force

The resultant force responsible for an object moving in circular motion. Centripetal forces always act towards the centre of the object's rotation.

Critical damping

The form of damping that reduces the displacement of an oscillating object to its equilibrium position in the quickest time possible and without further oscillation.

Damping

The dissipation of energy from an oscillating system. The consequence is that the amplitude of oscillation will decrease. This occurs when a force opposes the system's motion.

Forced vibrations

Repeated up and down oscillations, at the frequency of a driver. The amplitude of oscillation is small at high frequencies and large at low frequencies.

Free vibrations

Oscillations that are not caused by a driver. An object will naturally oscillate at its natural frequency.

Overdamping

A type of damping where the system is damped more than required to stop the oscillations. It takes longer for the system to return to equilibrium than for critical damping.

Radian

A unit of angle.

Resonance

This occurs when the frequency of oscillations is equal to the natural frequency of the oscillating system. The rate of energy transfer is at a maximum during this process.

Simple harmonic motion

Motion where the acceleration of an object is directly proportional, and in the opposite direction, to its displacement.

Underdamping

A type of damping where energy is gradually removed from the system and the amplitude of oscillations slowly decreases.

Angular speed

A measure of the speed of an object's angular rotation. It is equal to the frequency of rotation multiplied by 2𝝅.

Centripetal acceleration

The acceleration of an object moving in circular motion. Any object in circular motion must have an acceleration since the direction of the object, and therefore the velocity of the object, is constantly changing.

Centripetal force

The resultant force responsible for an object moving in circular motion. Centripetal forces always act towards the centre of the object's rotation.

Critical damping

The form of damping that reduces the displacement of an oscillating object to its equilibrium position in the quickest time possible and without further oscillation.

Damping

The dissipation of energy from an oscillating system. The consequence is that the amplitude of oscillation will decrease. This occurs when a force opposes the system's motion.

Forced vibrations

Repeated up and down oscillations, at the frequency of a driver. The amplitude of oscillation is small at high frequencies and large at low frequencies.

Free vibrations

Oscillations that are not caused by a driver. An object will naturally oscillate at its natural frequency.

Overdamping

A type of damping where the system is damped more than required to stop the oscillations. It takes longer for the system to return to equilibrium than for critical damping.

Radian

A unit of angle.

Resonance

This occurs when the frequency of oscillations is equal to the natural frequency of the oscillating system. The rate of energy transfer is at a maximum during this process.

Simple harmonic motion

Motion where the acceleration of an object is directly proportional, and in the opposite direction, to its displacement.

Underdamping

A type of damping where energy is gradually removed from the system and the amplitude of oscillations slowly decreases.

Breaking stress

The maximum stress that an object can withstand before failure occurs.

Brittle

An object with this property will show very little strain before reaching its breaking stress.

Centre of Mass

The single point through which all the mass of an object can be said to act.

Conservation of energy

Energy cannot be created or destroyed - it can only be transferred into different forms.

Conservation of momentum

The total momentum of a system before an event, must be equal to the total momentum of the system after the event, assuming no external forces act.

Couple

Two equal and opposite parallel forces that act on an object through different lines of action. It has the effect of causing a rotation without translation.

Density

The mass per unit volume of a material.

Ductile

A material that will show large amounts of plastic deformation, they can easily be drawn into wires. Eg. copper.

Efficiency

The ratio of useful output to total input for a given system.

Elastic behaviour

If a material deforms with this, it will return to its original shape when the deforming forces are removed. The object will not be permanently deformed.

Elastic collision

A collision in which the total kinetic energy of the system before the collision is equal to the total kinetic energy of the system after the collision.

Elastic limit

The force beyond which an object will no longer deform elastically, and instead deform plastically. Beyond this, when the deforming forces are removed, the object will not return to its original shape.

Elastic strain energy

The energy stored in an object when it is stretched. It is equal to the work done to stretch the object and can be determined from the area under a force-extension graph.

Equilibrium

When this occurs, both the resultant force and resultant moment acting on an object must be equal to zero.

Hard

A material that is difficult to cut or scratch, so it resists plastic deformation. Eg. diamond.

Hooke's Law

The extension of an elastic object will be directly proportional to the force applied to it up to the object's limit of proportionality.

Impulse

The change of momentum of an object when a force acts on it. It is equal to the product of the force acting on the object and the length of time over which it acts.

Inelastic collision

A collision in which the total kinetic energy of the system before the collision is not equal to the kinetic energy of the system after the collision.

Malleable

A material that shows large plastic deformation without cracking or breaking, they can be hammered into sheets or foils. Eg. gold.

Moment

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

Momentum

The product of an object's mass and velocity.

Newton's First Law

An object will remain in its current state of motion, unless acted on by a resultant force. An object requires a resultant force to be able to accelerate.

Newton's Second Law

The sum of the forces acting on an object is equal to the rate of change of momentum of the object. F=ma

Newton's Third Law

Every action has an equal and opposite reaction. If an object exerts a force on another object, then the other object must exert a force back, that is opposite in direction and equal in magnitude.

Plastic behaviour

If a material deforms with this, it will not return to its original shape when the deforming forces are removed. The object will be permanently deformed.

Principle of moments

For an object to be in equilibrium, the sum of the clockwise moments acting about a point must be equal to the sum of the anticlockwise moments acting about the point.

Scalar

A quantity that only has a magnitude. Examples include length, mass and temperature.

Stiff

A material with a high Young Modulus, a large stress is needed to cause a small extension. Eg. steel.

Spring constant

The constant of proportionality for the extension of a spring under a force. The higher this value is, the greater the force needed to achieve a given extension.

Stiffness

A measure of how difficult it is to stretch a given object.

Strength

The maximum stress that a material can tolerate before it fractures. This is not necessarily at the point of maximum extension.

Tensile strain

The ratio of an object's extension to its original length. It is a ratio of two lengths and so has no unit.

Tensile stress

The amount of force acting per unit area. Its unit is the Pascal (Pa).

Terminal speed

The maximum speed of an object that occurs when the resistive and driving forces acting on the object are equal to each other.

Tough

Materials that are not brittle, they do not crack easily. They exhibit a small plastic deformation when a large force is appled. Withstand large impact forces. Eg. steel.

Yield point

The point at which the material shows a big increase in extension (or strain) for a small increase in force (or stress).

Vector

A quantity that has both a magnitude and a direction. Examples include velocity, displacement and acceleration.

Young Modulus / e

The ratio of stress to strain for a given material. Its unit is the Pascal (Pa).

Amplitude

A wave's maximum displacement from its equilibrium position.

Antinode

A position of maximum displacement in a stationary wave.

Cladding

A protective layer on an optical fibre to improve the tensile strength of the fibre, prevent scratching and to prevent signal transfer between adjacent fibres.

Coherence

This occurs when waves have the same wavelength and frequency, as well as there being a fixed phase difference between them.

Diffraction grating

A grating with hundreds of slits per millimetre, that results in sharper interference patterns. They are used to calculate atomic spacing and to analyse elements.

Diffraction

The spreading of waves as they pass through a gap of a similar magnitude to their wavelength.

Electromagnetic waves

Waves that consist of perpendicular electric and magnetic oscillations.

Frequency

The number of waves that pass a point in a unit time period. It is the inverse of the time period.

Fringe spacing

The distance between two adjacent bright fringes or two adjacent dark fringes.

Interference

The name given to the superposition of waves that occurs when two waves meet. If the waves are in phase they will do so constructively, but if they are out of phase, they will do so destructively.

Laser

A light source that produces a collimated and coherent beam.

Longitudinal wave

A wave with oscillations that are parallel to the direction of energy propagation. Sound waves are an example.

Material dispersion

Waves of different wavelengths travel at slightly different speeds through an optical fibre and so reach the end of the fibre at slightly different times, causing pulse broadening. The use of monochromatic light fixes this.

Modal dispersion

Waves enter an optical fibre at slightly different angles, meaning the distance each beam has to travel is slightly different. This leads to the beams reaching the end at different times and so causes pulse broadening.

Node

A position of minimum displacement in a stationary wave.

Optical fibre

A thin glass fibre through which signals are passed through. They usually have cladding surrounding them.

Path difference

A measure of how far ahead a wave is compared to another wave, usually expressed in terms of the wavelength.

Phase difference

The difference in phase between two points on a wave. It is usually expressed in radians.

Phase

A measure of how far through the wave's cycle a given point on the wave is.

Polarisation

The restriction of a wave so that it can only oscillate in a single plane. This can only occur for transverse waves.

Pulse broadening

The elongation of a signal passed down an optical fibre, commonly due to modal or material dispersion.

Refractive index

A material property that is equal to the ratio between the speed of light in a vacuum, and the speed of light in a given material.

Snell's Law

A law linking a wave's angle of incidence to its angle of refraction, with the use of the refractive indexes of the mediums involved.

Speed

The product of a wave's frequency and wavelength.

Stationary wave

A wave that stores, but does not transfer, energy.

Total internal reflection

An effect that occurs in optical fibres, where full reflection occurs at the inside boundary of the fibre, meaning no radiation passes out.

Transverse wave

A wave with oscillations that are perpendicular to the direction of energy propagation. Electromagnetic waves are an example.

Wavelength

The distance between two identical positions on two adjacent waves. It is commonly measured from peak to peak or trough to trough.

Young's Double Slit Experiment

An experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes.

alpha decay

The process of an unstable nucleus emitting an alpha particle (two protons and two neutrons) to become more stable.

annihilation

The process of a particle and its antiparticle colliding and being converted into energy. The energy is released in two photons to conserve momentum.

antiparticle

All particles have a corresponding antiparticle with the same mass but opposite charge and conservation numbers.

baryon number

:A quantum number that is conserved in all particle interactions. Baryons have a baryon number of +1 and non-baryons have a baryon number of 0.

baryon

A class of hadron, that is made up of three quarks. The proton is the only stable baryon.

beta minus decay

The process of a neutron inside a nucleus turning into a proton, and emitting a beta-minus particle (an electron) and a antineutrino.

beta plus decay

The process of a proton inside a nucleus turning into a neutron, and emitting a beta-plus particle (a positron) and a neutrino.

electron diffraction

The spreading of electrons as they pass through a gap similar to the magnitude of their de Broglie wavelength. It is evidence of the wave-like properties of particles.

electron volt

The work done to accelerate an electron through a potential difference of 1V. 1eV is equal to the charge of an electron (E=qv).