Astronomy

Question 1

Does gravity change when you go to other planets and moons

Answer 1

Yes

Question 2

What is the equation for weight

Answer 2

Weight = mass x gravity

W = mg

Question 3

What does gravitational force cause these objects to do:
1. Planets in the solar system
2. The moon and artificial satellites
3. Comets in the solar system

Answer 3

1. Orbit the sun
2. Orbit the earth
3. Orbit the sun

Question 4

What is the equation for orbital speed

Answer 4

Orbital speed = (2 x pi x orbital radius)/time

(2 pi r)/t

Question 5

How does the orbit of a comet differ from the orbit of a moon or planet

Answer 5

Comets orbit in an elliptical path but moons and planets orbit in a circle

Question 6

What is a satellite

Answer 6

Something that orbits a larger object in space. Can be natural e.g. moons or man made e.g. telecommunication satellites

Question 7

What galaxy is the solar system in

Answer 7

The milky way

Question 8

What is the definition of a galaxy

Answer 8

A large collection of billions of stars

Question 9

What is the definition of the universe

Answer 9

A large collection of billions of galaxies

Question 10

What is the definition of the universe

Answer 10

A large collection of billions of galaxies

Question 11

What is orbital period

Answer 11

The time taken for an object to complete one full orbit

Question 12

When calculating the orbital radius of the moon, must you include the radius of the earth

Answer 12

Yes - measure from the centre of the earth

Question 13

What is the time period of the earth orbiting the sun

Answer 13

365.25 days

Question 14

How long does it take for the earth to rotate on its axis

Answer 14

24 hours

Question 15

How long does it take for the moon to orbit the sun

Answer 15

One month as an approximation but its actually 27 days

Question 16

What is the Doppler effect

Answer 16

The apparent change in frequency of a wave due to the relative motion between the source and observer

Question 17

What is a redshift

Answer 17

The measured wavelength is longer than the emitted wavelength - the object is moving away from the

Question 18

What is a blueshift

Answer 18

The measured wavelength is shorter than the emitted wavelength - the object is moving towards us

Question 19

What are the equations for the wavelengths of light and sound (4 parts)

Answer 19

(Observed wavelength - emitted wavelength)/emitted wavelength = change in wavelength/ emitted wavelength = Z (red shift constant) = V/C where c is the speed of light and V is the relative velocity

Question 20

What is CMB

Answer 20

Cosmic microwave background radiation - after the Big Bang, the radiation emitted cooled as it spread out. A radiotélescope can detect this constant hum of microwaves.

Question 21

What is the temperature of the universe

Answer 21

2.3K (but it is slowly going down)

Question 22

What is hubble’s law

Answer 22

The velocity of a galaxy is directly proportional to the distance from earth (straight line graph with gradient of 69.8)

V = H(constant of 69.8)d

Question 23

How is a red shift shown on a spectra of light

Answer 23

As the lines shift towards the red direction of the spectrum

Question 24

What is a nebula and what stage is it

Answer 24

First stage - clouds of dust and gas

Question 25

What does a nebula become and what is it

Answer 25

A protostar - the dust and gas collapse in due to gravity, meaning that the GPE is converted to KE, which increases core temperature. With high enough temperature and pressure, hydrogen fusion occurs, therefore forming a star

Question 26

What happens after a nebula to an average star

Answer 26

It becomes a main sequence star - like the sun. Hydrogen is fusing to Helium, releasing energy, causing the star to heat up.

Question 27

What is hydrostatic equilibrium

Answer 27

When the outwards pressure from the temperature equals the inwards pressure from gravity

Question 28

What happens to an average size main sequence star

Answer 28

After running out of hydrogen, it becomes a red giant. The star starts collapsing, so higher elements e.g. helium can fuse.

Question 29

What happens to an average size red giant

Answer 29

Eventually when too much iron has been fused in the core, the star collapses and explodes. This outer explosion of dust forms around the white dwarf core, making it a planetary nebula

Question 30

What happens to

Question 31

What happens to a planetary nebula

Answer 31

The gas around the white dwarf core eventually disperses, leaving behind a white dwarf

Question 32

What happens to a white dwarf

Answer 32

It cools and becomes a black dwarf (the universe isn’t old enough for this to have happened yet though)

Question 33

What happens to a massive star after the nebula stage

Answer 33

It becomes a main sequence star

Question 34

What happens to a massive main sequence star

Answer 34

It becomes a red super giant

Question 35

What happens to a red super giant

Answer 35

It becomes a supernova - an extremely powerful and bright explosion

Question 36

What happens to the most massive supernovas

Answer 36

It becomes a black hole

Question 37

What happens to the normal sized supernovas

Answer 37

It becomes a neutron star - a star made of neutrons which ejects powerful jets of matter

Question 38

Is a planetary nebula for massive or normal stars

Answer 38

Normal

Question 39

Which is for massive and which is for normal: planetary nebula, supernova

Answer 39

Normal - PN Massive - supernova

Question 40

What reaction type fuels a star

Answer 40

Fusion - two nuclei coming together to form a high mass nucleus

Question 41

What conditions do fusion reactions require and why

Answer 41

Very high temperature and pressure, to overrule the electrostatic repulsive force

Question 42

When does a star become classed ‘dead’

Answer 42

When it stops fusing hydrogen