Paper 1

Question 1

kelvin to degrees

Answer 1

k = c + 273.16

Question 2

thermal equilibrium

Answer 2

if two substances are in contact and one is hotter than the other there will be a new flow of thermal energy from the hotter object to the cooler object till they reach thermal equilibrium

Question 3

properties of solids

Answer 3

*strong electrostatic forces of attractions
* kinetic energy and they vibrate around their fixed positions

Question 4

properties of liquid

Answer 4

greater mean seperation
more kinetic energy still electrostatic attraction

Question 5

properties of gaseous phase

Answer 5

most kinetic energy
travel with random speed and direction

Question 6

brownian motion

Answer 6

molecules of a gas travel in random directions with random velocity, can be observed in smoke particles under a microscope, random movement because of collisions with other particles which transfers momentum

Question 7

internal energy

Answer 7

sum of the randomly distributed kinetic and potential energies associated with the atoms or molecules which make up the substance

Question 8

when a substance is heated but remains in the same state

Answer 8

kinetic energy of the molecules increases but the potential energy remains the same

Question 9

when a substance changes state

Answer 9

potential energy increases but the kinetic energy remains the same. temperature of the substance stays the same because the thermal energy is being used to overcome electrostatic bonds between molecules.

Question 10

absolute zero

Answer 10

this is at 0 kelvin and when all the molecules in a substance stop moving completely.

Question 11

specific heat capacity

Answer 11

energy required per unit mass to increase the temperature by 1k.

given by the equation E = mc∆𝜃

Question 12

how can we know the specific heat capacity of a substance using an electrical heater

Answer 12

1. known mass of a substance is heated by an electrical heater with known power for a given time
2. initial and final temperatures of the substance are measured.
3. energy transfer is equal to power multiplied by time, VI = mc∆𝜃/t and rearrange to find c.
4. an insulator is used around the substance to minions external energy transfer.

Question 13

Specific latent heat

Answer 13

energy required per unit mass to change the phase of a substance from solid to liquid

Question 14

Specific latent heat of vaporisation

Answer 14

energy required per unit mass to change the phase of a substance from liquid to gas, the formula being E = mL

Question 15

determine specific latent heat of a substance

Answer 15

use similar setup when an object is chasing phase the temperature is constant is used as the time when calculating the energy transferred to the substance

Question 16

how many particles in a mole

Answer 16

6.02x10^23 this can be determined by multiplying the number of moles of a substance by avagadros constant. the number of moleskin, of a substance is determined as
m = mass, M = molar mass

n = m/M

Question 17

how do particles in an ideal gas behave

Answer 17

• gas contains large number of atoms with brownian motion
• volume is negligible when compared to the total volume of the gas
• all collisions are perfectly elastic
  *time taken for atoms to collide is negligible compared to the time between collisions
• electrostatic forces between atoms are negligble except when colliding

Question 18

Boyles law

Answer 18

for a fixed mass of gas at a constant temperature the pressure is inversely proportional to the volume

Question 19

Charles law

Answer 19

for a fixed mass of gas at a constant volume, the pressure is proportional to temperature.

Question 20

what 2 laws are compiled to produce the pressure volume equation

Answer 20

pV =nRT

Charles law and Boyles law
p = pressure, V = volume, n = no. of. moles, R = molar constant, T temperature

Question 21

investigating Boyles law

Answer 21

pressure exerted is inversely proportional to its volume,
sealed syringe filled with gas connected to a pressure gauge. string can be used to vary the volume of the container and values of volume and pressure are recording.

Question 22

root mean square speed

Answer 22

pressure exerted by a gas and the mean kinetic energy of molecules in the gas are related to the root mean square speed of the molecules.

pV = 1/3 Nmc^2

Question 23

the Maxwell Boltzmann distribution

Answer 23

shows the number of molecules with each speed against speed c, area under the graph represents total number of molucules. as temperature increases the peak of the graph shifts to a higher speed

Question 24

Boltzmann constant

Answer 24

pV = nKT

Question 25

internal energy of an ideal gas

Answer 25

sum of the kinetic and potential energies, the kinetic energy is equal to the total internal energy as there are no electrostatic forces between the molecules

Question 26

angular velocity

Answer 26

rate of change of angle it is given by the formula w = ∆𝜃/t = 2(pi)(f)

Question 27

centripetal force

Answer 27

net force which acts perpendicular to the direction of the velocityy towards the centre of the circle. F = mv^2 /r v = 2πr/t = wr

Question 28

simple harmonic motion

Answer 28

type of oscillation where the acceleration of the oscillator is directly proportional to the displacement from the equilibrium position and acts towards the equilibrium position. a = -w^2x

Question 29

analysing simple harmonic motion, equations for the displacement of an oscillator

Answer 29

x = Asin(wt) x = Acos(wt)

Question 30

velocity and acceleration of oscillations

Answer 30

maximum velocity occurs at equilbrium position with the oscillator being stationary at the amplitude points. maximums accerlation occurs at the amplitude points and is 0 when the oscillator is at equilibrium v = +-W sqrt(A^2 - X^2)

Question 31

damping

Answer 31

the process by which the amplitude of the oscillations decreases over time this is due to energy loss to resistive forces such as drag and friction

Question 32

types of damping

Answer 32

light - occurs naturally and the amplitude decreases exponentially heavy - amplitude decreases dramatically critical - object stops before one oscillation is completed

Question 33

free oscillation

Answer 33

no external forces are being applied it oscillates at its natural frequency

Question 34

forced oscillation

Answer 34

occurs when a periodic driving force is applied to an object which causes it to oscillate at a particular frequency

Question 35

when does resonance occur

Answer 35

when the driving frequency of the external force applied to the object is the same as the natural frequency of the object resonance occurs

Question 36

what is resonance

Answer 36

when the amplitude of oscillation rapidly increases, and if there is no damping the amplitude will increase till the system fails

Question 37

gravitational field strength

Answer 37

gravitational force experienced per unit mass by an object at that point in a gravitational field. only works when the mass of the objects gravitational field is negligible compared to the external gravitational field the object is in

Question 38

newtons law of gravitation

Answer 38

two point masses attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of their seperation

Question 39

gravitational field strength for a point mass

Answer 39

can be given by dividing the gravitational force between two point masses but he mass of the other point mass. this shows the field strength for any object only depends on the mass of the planet and the distance between them.

Question 40

Keplers first law

Answer 40

the orbit of a planet is an ellipse with the sun at one focus. the motion can be modelled as circular

Question 41

Keplers second law

Answer 41

a line segment joining a planet and the sun sweeps out equal areas during intervals of equal time

Question 42

Keplers third law

Answer 42

the square of the orbital period is proportional to the cube of the average distance r from the sun

Question 43

satellites

Answer 43

objects that orbit other larger objects

Question 44

geostationary satellites

Answer 44

have an orbital period of one day they travel in the same direction as the rotation of the earth along the equatorial plane. therefore remaining above the same point on earth

Question 45

gravitational potential

Answer 45

work done per unit mass to move an object to that point from infinity

Question 46

escape velocity

Answer 46

for an object to escape a gravitational field produced by a mass M the kinetic energy of the object at the start must be equal to or greater than the gravitational potential energy required to lift it to infinity.

Question 47

planet

Answer 47

objects with mass sufficient for their own gravity to force them to take a spherical shape where no nuclear fusion occurs and the object has cleared its orbit of other objects

Question 48

dwarf planets

Answer 48

plants where the orbit has not been cleared of other objects

Question 49

asteroids

Answer 49

objects which are too small and uneven in shape to be planets

Question 50

comets

Answer 50

irregularly sized balls of rock dust and ice. orbit the sun in eccentric elliptical orbits

Question 51

solar systems

Answer 51

systems conrtaining stars and orbiting objects like planets

Question 52

galaxies

Answer 52

a collection of stars, dust and gas. Each galaxy contains around 100 billion stars

Question 53

what are nebulae

Answer 53

gigantic clouds of dust and gas and are the birthplace of all stars

Question 54

how do stars form?

Answer 54

over years the gravitational attraction between dust and gas particles pulls them together to form clouds. some regions become denser and pull in more dust and gas due to the gravitational collapse. the gravitational energy is converted to thermal energy. the resultant sphere of very hot dense dust and gas is a protostar

Question 55

what is a protostar

Answer 55

for a start to form the temp and pressure must be high enough for the hydrogen gas nuclei in the protostar to overcome the electrostatic forces of repulsion and undergo nuclear fusion this produces helium nuclei producing a star

Question 56

what initially happens to a star

Answer 56

remains in stable equilibrium the gravity forces act to compress the star but radiation pressure from photons emitted in fusion and gas pressure within the core counteract this keeping the size constant. this is the main phase of the star

Question 57

difference between larger stars

Answer 57

they are hotter and undergo fusion faster using up more available hydrogen, therefore have a shorter main phase,

Question 58

evolution of a low mass star to red giant

Answer 58

0.5m-10m, once hydrogen drops the gravity forces overcome radiation and gas so star begins to collapse inwards, turn into a red giant, the core of the red giant is too cool and the outer shell allows fusion to occur

Question 59

from red giant to white dwarf

Answer 59

evolved into a white dwarf outer shells drift off as planetary nebula, core remains very dense, has temperature around 3000k no fusion occurs.

Question 60

what stops white dwarfs collapsing

Answer 60

electron degeneracy pressure (as two electrons cannot exist in the same state)

Question 61

what is the Chandrasekhar limit

Answer 61

as long as the core mass is below 1.44M the white dwarf star is stable

Question 62

evolution of a massive star

Answer 62

>10M, hydrogen depletes helium fusion occurs into heavier elements forming a red supergiant.

Question 63

what is the red supergiant

Answer 63

has layers of increasingly heavy elements produced from fusion with an inert iron core, the star becomes unstable. a type 2 supernova occurs where there is a shockwave which ejects the materials in the outer shells out in to space and the core collapses

Question 64

what happens to a collapsed type 2 supernova

Answer 64

elements heavier than iron are formed in supernovas, if the remaining mass is greater than 1.44M, protons and electrons form neutrons. This makes a neutron star, if the mass is greater than 3M the gravitational forces are so strong the escape velocity of the core is greater than the speed of light, this is a black hole.

Question 65

What are electron levels

Answer 65

bound to an atom can only exist in certain discrete energy levels, each element has its own set of energy levels. when an electron is excited it moves up when it is the opposite it moves towards the down state, releases photon with a specific wavelength

Question 66

emission line spectra

Answer 66

each element produces a unique emission line spectrum because of the unique set of energy levels associated with its electron

Question 67

continuous line spectra

Answer 67

all visible wavelengths of light are present produced by heated solid metals

Question 68

absorption line spectra

Answer 68

dark spectral lines against background of the continuous spectrum with each line corresponding to a wavelength of light used to excite atoms of that element.

Question 69

diffraction grating

Answer 69

regularly spaced slits that can diffract light, different colours of light have different wavelength have different wavelengths so will be directed at different angles. dsinx = n(lamda)

Question 70

Weins law

Answer 70

the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the temperature of the object. where lamda is the wavelength of light produced with maximum intensity, T is the absolute surface temp (lamda)(temp) = 2.9x10^-3

Question 71

stefans law

Answer 71

for a black body, the total radiant heat energy emitted from a surface is proportional to the fourth power of its absolute temperature. used to relate temp with luminosity

Question 72

distances

Answer 72

Astronomical Unit = 1.5 x 10^11 average distance from earth to sun light year = light travels in one year

Question 73

arc minutes and arcseconds

Answer 73

one degree there are 60 arc minutes and 3600 arc seconds

Question 74

what is a Parsec

Answer 74

the distance at which a radius of 1 AU subtends an angle of 1 arcsecond in metres, 1 Parsec is 3.1x10^16

Question 75

what is parallax

Answer 75

can be used to measure the distance to nearby stars, it is the apparent shift in position of an object against a backdrop of distance objects that dont appear to move accurate up to 100pc

Question 76

cosmological principle

Answer 76

the universe is isotropic (same in all directions no centre or edge) and homogenous, and the laws of physics are universal.

Question 77

doppler effect

Answer 77

apparent shift in wavelength occurring when the source of the waves is moving. if moving to detector wavelength appears to decrease, otherwise contrary

Question 78

Doppler effect in starlight

Answer 78

shifts the position of spectral lines, can be used to determine relative speed of a star ∆wavelength/wavelength = v/c

Question 79

Hubbles law

Answer 79

recessional velocity of a galaxy is proportional to its distance from earth, further away the star the faster it is moving away from us V = Hd

Question 80

universes expanding Hubbles law

Answer 80

all light from distant galaxies are red shifted showing they are moving away from earth fabric of space time expanding

Question 81

Big Bang theory evidence

Answer 81

all objects were initially contained in a singularity which suddenly expanded outwards. - microwave background radiation originally high energy gamma photons were distributed across the universe

Question 82

evolution of universe

Answer 82

10^-35 s = universe expands rapidly with accerlation known as inflation. no matter only high energy gamma photons and em radiation 10^-6 s =first fundamental particles gain mass 10^-3 s =most mass is created using pair production hadrons come from quarks 1s = production of mass halted

Question 83

dark energy

Answer 83

used to explain the accelerating expansion and should make up 68% of the total energy in the universe