Definitions - ALL Flashcards
Instantaneous Speed
the rate of change of distance at one particular time
Projectile Motion
a projectile is an object moving through the air under the influence of only one force (gravity) - trajectory is a parabola
Terminal Velocity
when the upwards air resistance is equal to the downwards gravitational force, the object will no longer accelerate and has reached terminal velocity
Newton’s First Law
“an object continues in uniform motion in a straight line or at rest unless a resultant external force acts.”
Newton’s Second Law
“the resultant force on an object is proportional to the acceleration providing the mass of the object remains constant.”
Newton’s Third Law
“for every action on one object there is an equal but opposite reaction on another object.”
i.e. forces come in pairs and will be of the same type
Hooke’s Law
the extension of a spring is proportional to the applied force
F=K change in X
Work
said to be done when an object moves through a displacement
therefore it is a transfer of energy
Power
the rate at which work is done or energy is transferred
Linear Momentum
the product of mass and velocity
Conservation of Momentum
“the total linear momentum of a system remains constant provided no resultant external force acts.”
Displacement - oscillations
instantaneous distance from the equilibrium position in a specific direction (m)
amplitude - oscillations
the maximum displacement from the equilibrium position (m)
frequency - oscillations
number of oscillations per second (Hz)
period - oscillations
time for one oscillation (s)
phase - oscillations
measure of how “in step” different particles are (one cycle = 360 degrees or 2pi radians)
Simple Harmonic Motion
is a type of oscillation where the objects acceleration (and hence force) is:
- proportional to the objects displacement from the equilibrium position
- but in the opposite direction to displacement
Longitudinal Waves
the particles in the medium vibrate parallel to the direction of energy transfer
Transverse Waves
the particles of the medium vibrate at right angles to the direction of energy transfer
Displacement - waves
distance the medium has moved from the equilibrium position in a particular direction
Frequency - waves
number of complete waves passing a point per second (Hz)
Period - waves
time for one complete oscillation of the medium (or time for one complete wave to pass a given point)
Wavelength
shortest distance between two points that are in phase along a wave
Wave Speed
distance travelled per unit time by the energy of the wave
Amplitude - waves
maximum displacement of the medium from the equilibrium position
Intensity of a wave
power per unit area received by an observer
Total Internal Reflection
will occur when:
- light is travelling from a more to a less optically dense medium
- the angle of incidence at the boundary is greater than the critical angle
Diffraction
when waves move past an obstacle or through a gap, they tend to spread out - longer the wavelength the more they spread out
Principle of Superposition
if two or more waves meet, the resultant displacement at any point is found by adding the displacements produced by each individual wave
Conditions for formation of standing waves
the two waves of the same type meet they must be:
- of the same amplitude
- of the same frequency
- travelling in opposite directions
Polarisation
if and EM wave such as light is polarised, the electric field vector is oscillating in one plane only
Brewster’s Law
when light reflects off a surface it will be polarised in the plane of the surface
if angle between reflected ray an refracted ray = 90 degrees then polarisation is 100%
Malus’ Law
polarising filters
is unpolarised light passes through a polariser it will be reduced by half
Newton’s Law of Gravitation
every single point mass attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of their separation
Gravitational Field
a region of space where a mass experiences a force because of its mass
Gravitational Field Strength
the force per unit mass experienced by a small point test mass placed in the field
Avogadro constant (NA)
the number of atoms in 12g of 12C
boiling
takes place throughout a liquid and always occurs at the same temperature
Boyle’s law
at a constant temperature, the pressure of a gas is inversely proportional to its volume
Charles’ law
at a constant pressure, the volume of a gas is proportional to its temperature (in K)
evaporation
takes place at the surface of a liquid and can happen at all temperatures
internal energy
the sum of the total intermolecular potential energy and the total random kinetic energy of the molecules in a substance
isothermal
constant temperature
molar mass
the mass of one mole of a substance
mole (m)
the amount of a substance that contains the same number
of atoms or molecules as the number of atoms in 12g of 12C
pressure law
at a constant volume, the pressure of a gas is proportional to its temperature (in K)
specific heat capacity (c)
the amount of energy required to raise the temperature of the unit mass of a substance by 1K
specific latent heat (L)
the amount of energy per unit mass of a substance
absorbed or released during a change of phase (with no temperature change)
temperature
a measure of the average random kinetic energy of the molecules in a substance
thermal capacity (C)
the amount of energy required to raise the temperature of an object by 1K
thermal equilibrium
a situation where objects are at the same temperature
thermal energy
the energy that is being transferred between two objects of different temperatures
Main Properties of an Ideal Gas
- undergo perfectly elastic collisions between themselves and the walls of their container
- have no intermolecular forces between them (therefore internal energy = total kinetic energy)
- follows the three gas laws
this model breaks down at low temperatures and high pressures
Electric Field
a region of space where a charged object experiences a force due to its charge
Electric Field Strength
the force per unit charge that a experienced by a small positive test charge when placed in the field
Potential Difference
the work done (or energy transferred) when one unit of charge moves between two points
Current
the rate of flow of electric charge
Resistance
the ratio of potential difference across the component to current flowing through the component
Ohm’s Law
the current flowing through a piece of metal is proportional to the potential difference across it providing the temperature is constant
Light Dependent Resistors
as the light intensity decreases the resistance of the LDR increases
Thermistors
as the temperature increases, the resistance of the thermistor decreases
Electrical Power
amount of energy used or supplied per unit time
EMF
energy supplied per unit charge by the power source to the circuit
Isotopes
different nuclei of an element that have different number of neutrons
Half Life
the time taken for half of the nuclei in a sample to decay (or for the activity to fall to 50% of the initial value)
