Unit 1-2 Physics Exam Prep

All three topics including linear motion, waves and nuclear physics.

Scalars

Quantities that have magnitude but no direction.

Vectors

Quantities that have both magnitude and direction.

Distance

The total length of the path travelled by an object, regardless of direction.

Displacement

The distance travelled by an object in a specific direction.

Speed

The rate at which distance changes in meters per second.

Velocity

The rate at which displacement changes, with an included direction, in meters per second.

Acceleration

The rate of change of velocity.

Force

A push or pull upon an object that results from the object's interaction with another object.

Upthrust

The push upwards of something in a fluid.

Friction

The resistive force between two moving objects that are in contact or a moving object in contact with a stable object.

Air resistance

The push upwards of air as something falls through it.

Drag

A resistive force that acts in the opposite direction of an object moving through a fluid.

Normal force

The force that is upwards and perpendicular to a surface.

Tension

The pulling force acting on a wire when it is pulled tight by forces acting from opposite ends.

Electrostatic force

The push or pull of charged particles.

Magnetic force

The push or pull force exerted by magnets or electrically charged particles.

Weight

The effect of gravity on an object's mass.

Inertia

The reluctance of a body to change its velocity.

Newton's first law

Objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an opposing external unbalanced force.

Newton's second law (definition)

The direction of the acceleration of an object is in the direction of the net external force acting on it and proportional to the size of the force and inversely proportional to the mass.

Newton's second law (formula)

F = ma, where F is the net force acting on an object, m is the mass of the object and a is the acceleration of the object.

Air resistance proportionality

The air resistance acting on an object is directly proportional to the square of the speed of the object.

Terminal velocity

The top speed an object can reach when falling through a gas or liquid.

Newton's third law

Every action has an equal and opposite reaction.

Momentum

The product of a body's mass and velocity, represented by the formula p = mv, measured in units kg/m/s.

Impulse

The change in an object’s momentum from one point in time to another.

Law of conservation of momentum

The total momentum of an isolated system remains constant if no external forces act on it.

Energy

A property of matter and systems that describes the capacity to do work or cause a change.

Work

The energy transferred to or from an object when a force acts on it while it moves a distance.

Potential energy

Stored energy that an object or system has because of its position, shape or arrangement relative to other objects within a force field.

Gravitational potential energy

The stored energy an object has because of its place in a gravitational field.

Kinetic energy

The energy an object has because of its motion.

Power

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

Impulse (formula)

I = ΔF*t = m*Δv, where ΔF is the net force applied to an object, t is the duration the force is applied for, m is the mass of the object and Δv is the change in velocity over the same time frame.

Work done by a force on an object

W = F*S*cos(x), where F is the applied force, S is the displacement of the object and x is the angle between the force and displacement.

Elastic interactions

Interactions where momentum and kinetic energy are conserved with no dissipation to other forms of energy.

Inelastic interactions

Interactions where momentum is conserved but some kinetic energy of the colliding particles is transformed into other forms of energy.

Completely inelastic interactions

Interactions where the colliding objects stick together after impact, maximising the loss of kinetic energy.

Wave

A disturbance or oscillation in particles or space that results in the transfer of energy from one place to another.

Mechanical wave

A wave that requires a medium to propagate

Electromagnetic wave

A wave that does not require a medium to propagate

Propagation

The way waves travel and spread energy throughout space or a medium.

Wavelength

The distance between corresponding points on a successive wave EG peak to peak, trough to trough.

Amplitude

The maximum displacement of a wave from its equilibrium.

Crest/peak

The highest point a wave reaches above the equilibrium, indicating maximum positive displacement.

Trough

The lowest point a wave goes below the equilibrium, indicating maximum negative displacement.

Medium

A material or substance that carries energy from one place to another.

Frequency

The number of waves that move past a point in one second.

Period

The time, in seconds, it takes for one wavelength to be completed.

Transverse wave

A wave where the oscillation of particles is perpendicular to the equilibrium, including all waves on the electromagnetic spectrum.

Pulse

An isolated, single disturbance that travels through a medium

Periodic wave

A continuous, repeating series of disturbances within a medium, travelling with constant speed.

Longitudinal wave

A wave where the oscillation of particles is parallel to the equilibrium, including all sound waves.

Compressions

Segments of a longitudinal wave that have high particle density.

Rarefactions

Segments of a longitudinal wave that have low particle density.

Velocity (formula)

The frequency of the waves times by the wavelength.

Polarisation

The restriction of the directions of oscillation for transverse waves.

Angle of incidence/reflection

The angle of incidence is the angle at which light approaches an object relative to the normal, and the angle of reflection is the angle at which light travels away from an object compared to the normal.

Law of reflection

The angle of incidence is equal to the angle of reflection when compared to the normal.

Refraction

The principle that light is deflected while passing through the interface between one medium and another.

Snell's law

n1Sin(i) = n2Sin(r), where n is the refractive index of the respective object, i is the angle of incidence and r is the angle of refraction.

Diffraction

The bending of waves around obstacles or the spreading of waves as they pass through small openings.

Wavefront

A surface over which an oscillation or wave phase is constant.

Huygen's principle

Every point on a wavelength acts as a source of secondary spherical wavelets. The new wavefront is tangent to the wavelets.

Factors affecting diffraction

Longer wavelengths diffract more than shorter wavelengths and smaller apertures cause greater diffraction.

Principal focus

A specific point on the principal axis where parallel light rays converge or diverge from.

Principle of superposition

The overall displacement between two colliding waves is the sum of the individual displacements of the contributing waves.

Constructive interference

When two waves superpose such that their peaks align, resulting in higher amplitudes.

Destructive interference

When two waves superpose such that the peak of one aligns with the trough of another, resulting in the cancellation of amplitudes.

Standing waves

A wave pattern formed by the superposition of identical waves traveling in opposite directions. The length must be a multiple of ½ λ.

Forbidden standing waves

Waves that collapse because their wavelength does not match the space containing the wave, EG when the wavelength is not a multiple of ½ λ.

Nodes

Points along a standing wave that remain stationary due to the cancellation of amplitudes from destructive interference.

Antinodes

Points along a standing wave created by constructive interference, resulting in alternations between maximum and minimum.

Wave speed

V = fλ in one dimension, where v is speed, f is frequency in hertz, and λ is wavelength.

Harmonic frequency

The frequency produced by the natural vibrations in objects.

Fixed end waves

A wave that reflects backwards upside down from a fixed boundary, creating a standing wave with nodes and antinodes.

Resonance

When an object vibrates with maximum amplitude when exposed to a wave that matches its natural frequency.

Free vibrations

Vibrations that occur naturally in a system without external driving forces.

Electromagnetic force

A fundamental, long-range force that acts between electrically charged particles, resulting in a force of attraction between oppositely charged particles and repulsion between similar charges.

Gravitational force

A fundamental, long-range force of attraction between two objects with mass.

Strong nuclear force

A fundamental, short-range force that acts as attraction/repulsion depending on the distance between particles. It acts as the 'glue' that holds atomic nuclei together through the neutrons holding the protons in place.

Weak nuclear force

The fundamental force responsible for particle decay and the change in characteristics of quarks.

Ionising radiation

High energy radiation that can affect the electrons surrounding an atom so that a charged ion is formed. It includes all wavelengths from ultraviolet to gamma radiation, with alpha and beta particles also included.

Non-ionising radiation

Electromagnetic radiation with low energy, ranging from wavelengths of radio waves to that of visible light.

Antimatter

A form of matter which consists of antiparticles, which have the same properties as particles but opposite charges.

Anti-particles

They have the same properties as particles, however they have opposite charges. They include antiprotons, antineutrons and positrons.

Decay series

A series of radioactive transmutations that an unstable nucleus undergoes to decay until it reaches a state of stability.

Alpha decay

A type of decay where a positively charged helium nucleus, containing 2 protons and 2 neutrons, is emitted from an atom.

Beta negative decay

A type of decay where a neutron spontaneously converts into a proton, emitting an electron and an antineutrino in the process.

Beta positive decay

A type of decay where a proton spontaneously converts into a neutron, emitting a positron and a neutrino in the process.

Gamma decay

A type of decay that usually accompanies alpha or beta decay, consisting of a high-energy photon with no rest mass or charge.

Transmutation

Where an unstable element undergoes decay and emits a particle, with the goal of bringing the unstable element closer to being stable.

Inverse-square law

The intensity of radiation from a source is inversely proportional to the square of the distance from the source.

Inverse penetrative/ionising ability

The penetrative ability of a decayed particle is inversely proportional to its ionising ability.

Geiger muller counter

A device that counts the number of radioactive particles that collide with the sensor of the device.

Half-life

The average amount of time it takes for half of all radioactive isotopes of an element to decay.

Half-life formula

N = N0 (1/2)^n, where N is the amount of particles remaining after decay, N0 is the original number of particles and n is the number of half lives that have passed.

Atomic mass units

The unit of measurement for subatomic particles, equal to 1.66 * 10^-27kg.

Electron volts

An alternative unit for energy, defined as the energy an electron gains when subjected to one volt of potential difference. It is equal to 1.6 * 10-19 Joules.

Natural transmutation

One nuclei spontaneously decaying into a daughter nuclei.