AP Physics

Precision

The tightness of the spread of the data

Accuracy

The closeness to the true value of the data

Systematic Error

An error caused by a fault in the measuring equipment. Cannot be averaged out

Random Error

An error caused by a change in technique (human error). Can be averaged out

Thermal Contact

When two objects can exchange energy between them

Thermal Equilibrium

Two objects in thermal contact cease to have any exchange of energy

0th Law of Thermodynamics

If bodies A and B are in thermal equilibrium with body C, but separate from one another, the A and B will be in thermal equilibrium with each other if places in thermal contact

Thermal Energy

the combined microscopic kinetic and potential energies

Thermometer

any small macroscopic instrument used to measure the thermal energy of a system that undergoes a measurable change when subject to a change in thermal energy

Absolute 0

When there are no collisions of particles in a system

Specific Heat Capacity

The amount of heat required to change the temperature of 1kg of substance by 1C

Specific Latent Heat

the amount of heat required to change the phase of 1kg of substance by 1C without a change in temperature

Isotope

Atoms of the same element with a different mass number

Mass Defect

the difference between the mass of a particular nucleus and the total mass of its constituent parts

Binding Energy

The energy required to completely disassemble the nucleus of an atom into its constituent parts

Binding Energy per Nucleon

The average amount of energy required to remove an individual nucleon from a nucleus

Decay Constant

the probability per unit time that a nucleus will decay

Decay Rate

The number of disintegrations per second

Half Life

The time takes for half of the original nuclei to decay

Four fundamental forces

Gravitational Force, Strong Force, Weak Force, Electromagnetic Force

Gravitational Force

Attraction of objects that have mass or energy Graviton

Electromagnetic Force

The force between charged particles. Photon

Strong Force

Binds the fundamental particles together. Pions (particles) and Gluons (quarks)

Weak Force

Responsible for particles decay. W Bosons

Hadrons

All particles affected by the strong nuclear force. (Baryon and Meson)

Leptons

Particles not affected by the strong nuclear force

Bosons

Exchange particles

Leptons (list)

electron/positron and neutrino/anti-neutrino

Baryon

Consists of 3 quarks

Meson

Consists of 2 quarks

Conservation of Baryon number

Baryons (B=+1), Antibaryons (B= -1), all other particles (B= 0)

Conservation of Lepton number

Leptons (L = +1), Antileptons (L = -1), all other particles (L= 0)

Proton - Proton Fusion

1. Two protons fuse and form deuterium

2. A third proton fuses with the deuterium resulting in helium-3

3. Two helium-3 atoms fuse and create beryllium-6

4. The beryllium-6 decays into helium-4 and 2 protons

Wiens Displacement Law

For a blackbody (or star), the wavelength of maximum emissions of any body in inversely proportional to its absolute surface temperature

Blackbody

An object that is perfect at absorbing and emitting radiation

Classes

OBAFGKM

Luminosity

The measure of the amount of light

emitted by an object per second

Factors that affect Luminosity

Distance from the earth and the amount of energy radiated by the star

Apparent Brightness

The intensity received at the Earth

Mass Luminosity Relation

As luminosity increases, so does Mass by a factor of 4

Chandrasekhar Limit

determines if a star is white dwarf

Oppenheimer - Volkoff Limit

The upper limit of a neutron star before it collapses into a black hole

Protostar

a smaller young star still forming from the parent gas cloud. Produces energy due to reactions on the surface of the star

Proportions of matter

Matter - 5%, Dark matter - 26%, Dark energy - 69%

Dark Matter

Responsible for how galaxies are organised

Dark Energy

Responsible for the expansion of the universe

Gravitational Lensing

Can be measured, occurs between galaxies and can be reverse engineered to prove dark matters existence

Centripetal Acceleration

The acceleration that points towards the center of a circle

Centripetal Force

The resultant force that acts towards the center of the circle causing the centripetal acceleration

Factors of a Force to cause rotation

1. magnitude of the force

2. distance from the point of application to the pivot

3. angle at which the force is applied

Torque

A force as its tendency to cause a body to rotate about a fixed point or axis

Static equilibrium

When an object is completely stationary. (No net force, therefore sum of forces = 0 and sum of and torque = 0;

Gravitational field

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

Electric field

A region in space where a charge experiences a force.

Electric field strength

The electric force per unit positive charge.

Uniform electric field

An electric field with constant magnitude and direction, typically created between two parallel plates.

Magnetic field

A region in space where a moving charge experiences a magnetic force.

Oscillation

Back and forth periodic motion.

Periodic motion

Any motion that repeats itself at regular time intervals.

Simple harmonic motion (SHM)

Occurs when a linear restoring force is exerted on an object displaced from an equilibrium position.

Amplitude

The maximum displacement from the equilibrium position in an oscillation.

Period (T)

The time taken to complete one full cycle of oscillation.

Frequency (f)

The number of oscillations completed per second.

Angular frequency (ω)

The rate of change of the phase of the oscillation; ω = 2πf.

Phase difference (φ)

The difference in the positions or states of two oscillating objects, measured in degrees or radians.

Restoring force

A force that acts to return a system to its equilibrium position.

Velocity selector

A device using perpendicular electric and magnetic fields to select particles of a specific velocity.

Geostationary satellite

a satellite that orbits the Earth at the same speed as the Earth's rotation

Kepler’s First Law

Planets move in elliptical orbits with the Sun at one focus.

Kepler’s Second Law

A line drawn between the Sun and a planet sweeps out equal areas during equal intervals of time.

Kepler’s Third Law

The square of a planet’s orbital period is proportional to the cube of the semi-major axis of its orbit

Potential energy in SHM

Energy stored in the system due to displacement; \( U = \frac{1}{2}kx^2 \).

Kinetic energy in SHM

Energy of motion during oscillation; \( K = \frac{1}{2}mv^2 \).

Total mechanical energy in SHM

The sum of kinetic and potential energy; conserved in an ideal system.