Paper 1 COPY Flashcards

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1
Q

how do particles in an ideal gas behave

A
  • 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
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2
Q

Keplers first law

A

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

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3
Q

Keplers second law

A

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

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4
Q

Keplers third law

A

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

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5
Q

satellites

A

objects that orbit other larger objects

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6
Q

geostationary satellites

A

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

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7
Q

gravitational potential

A

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

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8
Q

escape velocity

A

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.

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9
Q

planet

A

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

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10
Q

dwarf planets

A

plants where the orbit has not been cleared of other objects

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11
Q

asteroids

A

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

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12
Q

comets

A

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

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13
Q

solar systems

A

systems conrtaining stars and orbiting objects like planets

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14
Q

galaxies

A

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

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15
Q

what are nebulae

A

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

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16
Q

how do stars form?

A

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

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17
Q

what is a protostar

A

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

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18
Q

what initially happens to a star

A

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

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19
Q

difference between larger stars

A

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

20
Q

evolution of a low mass star to red giant

A

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

21
Q

from red giant to white dwarf

A

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

22
Q

what stops white dwarfs collapsing

A

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

23
Q

what is the Chandrasekhar limit

A

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

24
Q

evolution of a massive star

A

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

25
Q

what is the red supergiant

A

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

26
Q

what happens to a collapsed type 2 supernova

A

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.

27
Q

What are electron levels

A

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

28
Q

emission line spectra

A

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

29
Q

continuous line spectra

A

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

30
Q

absorption line spectra

A

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.

31
Q

diffraction grating

A

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)

32
Q

Weins law

A

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

33
Q

stefans law

A

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

34
Q

distances

A

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

35
Q

arc minutes and arcseconds

A

one degree there are 60 arc minutes and 3600 arc seconds

36
Q

what is a Parsec

A

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

37
Q

what is parallax

A

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

38
Q

cosmological principle

A

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

39
Q

doppler effect

A

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

40
Q

Doppler effect in starlight

A

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

41
Q

Hubbles law

A

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

42
Q

universes expanding Hubbles law

A

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

43
Q

Big Bang theory evidence

A

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

44
Q

evolution of universe

A

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

45
Q

dark energy

A

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