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Physics > Astronomy > Flashcards

Astronomy Flashcards

1
Q

How are planets’ orbits similar

A

They have an elliptical orbit and they orbit the sun.

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2
Q

How are planets’ orbits different

A

They have different orbital radii

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3
Q

How can some moons be faster than others considering the fact that they are orbiting larger planets?

A

Orbital radii of the 2 moons are different; one moon has a orbit radius larger than the other

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4
Q

Supernova

A

An explosion where the outer layer of stars is ejected

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5
Q

Black hole

A

an area of such immense gravity that not even electromagnetic waves such as light can escape from it

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6
Q

How stars produce energy

A

Nuclear Fusion and there are lots of reactions occurring on stars

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7
Q

What waves do black holes emit

A

X-rays

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8
Q

Why does a star remain stable

A

Radiation pressure and gravitational forces are equal

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9
Q

How does a star form (2)

A

Dust and gas particles are pulled together and clumped by gravitational forces pulling inwards

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10
Q

Differences between a protostar and a main sequence star

A

Protostar is at a lower temperature because nuclear fusion’s not started

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11
Q

How does the universe contain a large variety of different elements

A
  • Nuclear fusion takes place within stars where hydrogen nuclei fuse to form helium
  • Fusion continued and formed larger elements.
  • Elements larger and heavier than iron were formed during a supernova
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12
Q

Why is the rate of nuclear fusion in a larger star faster than in a smaller star?

A

larger stars have a shorter main sequence period hence, they use up the hydrogen at a faster rate and therefore they have a faster rate of nuclear fusion occurring

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13
Q

What is meant by the big bang theory?

A

Universe started from a point of singularity where all matter was concentrated and an explosion occurred which sent the matter outwards

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14
Q

What does a larger orbital radius of a planet tell you about its speed?

A

If the planet moves further away from the star, it has to move faster to keep going around it. So, if a planet is far away, it has to go faster than if it is close

Larger the orbital radius of a planet –> The faster it travels

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15
Q

Gravitational field strength is measured in

A

N/kg

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16
Q

There are billions of galaxies in the

A

Universe

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17
Q

Why does a telescope travel fastest when it’s closest to the Earth?

A
  • Gravitational forces increase when it’s closer to the Earth
  • mass remains constant
  • hence, it accelerates
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18
Q

Difference between X-rays and Visible Light?

A

X-rays have a shorter wavelength compared to Visible Light
X-rays have a higher frequency compared to Visible Light

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19
Q

Why does the distance between 2 planets vary?

A

They travel at different speeds and have different orbits

20
Q

There is a vehicle on mars, Why is the speed kept so low?

A

There is a time delay and also damaged is reduced if there is a collision

21
Q

Why does a comet travel fastest at that point nearest to the Sun?

A

The comet is closest to the Sun at that point hence, the gravitational forces are strongest at that point

22
Q

Why is a 24-hour orbit of a satellite an advantage for communication?

A

The satellite always appears in the same part of the sky

23
Q

Describe the evolution of stars of similar mass to the sun

A
  • a cloud of dust and gas particles clump together due to gravitational forces pulling inwards, therefore, forming a protostar
  • Nuclear fusion occurs which releases energy and creates outwards pressure hence, a main sequence star is formed which remains stable for long periods of time
  • Hydrogen runs out therefore, the star collapses, becoming unstable and then turns into a red giant. Helium fusion begins on the Red Giant. Once the helium fusion stops, the red giant contracts to form a white dwarf
  • As the white dwarf cools, the black dwarf forms
24
Q

Explain what red shift is and how it provides evidence that the universe is expanding (6 marks)

A
  • light from galaxies shifts towards the red end of the spectrum
  • wavelength increases as galaxies move further away
  • hence, the farther away the galaxy is and the faster it’s moving away, the greater the redshift
  • therefore, showing galaxies are moving away
  • and that the universe is expanding
25
Q

Why do astronomers usually give the distance from stars as a number of light years instead of kilometres?

A

Distance is too great

26
Q

Describe how careful observation of electromagnetic radiation from distant galaxies and from the whole of space gave evidence supporting Big Bang Theory (6 marks)

A
  • light from galaxies shifts towards the red end of the spectrum
  • wavelength increases as galaxies move further away
  • hence, the farther away the galaxy is and the faster it’s moving away, the greater the redshift
  • therefore, showing galaxies are moving away
  • and that the universe is expanding
27
Q

Describe how the process continues for stars much more massive than the Sun

A
  • After H in main sequence stars runs out, star expands and cools to form a red super giant
  • red super giant explodes into a supernova when outwards pressure is too great
  • remains are a neutron star
  • or a black hole the star was exceptionally massive
28
Q

“The smaller the planet, the shorter its period of orbit”
Evaluate the statement

A

Correct = smaller an object’s orbit, the faster the object travels to increase its velocity and smaller planets travel faster

29
Q

Why do planets nearer to the star take less time to orbit the star?

A

The planets have a shorter orbital path

30
Q

What evidence is there to suggest that the Sun was formed form the material produced when an earlier star exploded?

A

There is presence of nuclei of the heaviest elements

31
Q

Why might scientists think one theory is wrong?

A

New evidence can’t be explained by that theory

32
Q

Define red shift

A

It’s when the wavelength increases

33
Q

Why does red-shift provide evidence that the universe is expanding? (2)

A
  • Red shift provides evidence that the distance of galaxies is increasing
  • Red shift supports the idea of an expanding universe
34
Q

Why might scientists be keen to carry out new research if one theory is similar to another?

A

To find more evidence to support one theory

35
Q

How might the universe have started?

A

From an explosion

36
Q

Explain briefly one piece of evidence which may be used to support that the universe started from an explosion (3 - RS)

A
  • Light from galaxies shifts to the red end of the spectrum
  • The further away the galaxies, the greater the redshift
  • Therefore indicating galaxies are moving away
37
Q

What should scientists do when a theory does not appear to be supported by new data? (2)

A
  • Amend the theory
  • Check the reliability of data
38
Q

Why are there telescopes that detect different types of electromagnetic waves to observe the universe?

A

There are sources emitting different types of electromagnetic waves

39
Q

Are red giants brighter and hotter than the main sequence?

A

Red giants are cooler but brighter than the main sequence as it’s more powerful

40
Q

How is a main sequence star formed from a nebula (3)

A
  • dust and gas particles clump together due to gravitational forces pulling inwards
  • Hence, forming the protostar
  • Nuclear fusion occurs on protostar to form the main sequence star
41
Q

How does a main sequence star form a white dwarf

A
  • Main sequence star collapses
  • Main sequence star expands to form Red Giants
  • Surface temperature of red giant decreases
  • Helium fusion occurs
  • Once helium fusion stops, red giant condenses into a hot and dense white dwarf
42
Q

What does nuclear fusion do in terms of energy?

A

Nuclear Fusion releases energy

43
Q

Define absolute magnitude

A

Measurement of the brightness of a star at a standard distance of 10 parsecs

44
Q

During nuclear fusion and nuclear fission, what energy store of the star increases

A
  • Fusion:
  • Energy store that increases: Kinetic
  • Fission:
  • Energy store that increases: Thermal
45
Q

Describe the evolution of the universe from the Big Bang until the present day

A
  • Supernova explosion occurred and layer of stars was ejected outwards
  • Galaxies moved away
  • and the Universe expanded
46
Q

How is Helium, Carbon and Hydrogen formed in stars and galaxies?

A
  • Stars are mostly made of hydrogen
  • Helium and carbon is formed during fusion

Physics (9 decks)

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