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Physics > SP7 > Flashcards

SP7 Flashcards

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1
Q

What is a geocentric model

A

Model that Ptolemy made that states that the other planets and the sun orbited the Earth

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2
Q

What is a heliocentric model

A

Model suggested by Copernicus that stated the sun was in the centre and we all orbited it

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3
Q

What’s a difference between Ptolemy and Copernicus’ models

A

In Ptolemy’s models, the planets orbited the Earth. In Copernicus’, they orbited the sun. Ptolemy’s model had planets that moved in small circles while orbiting the Earth

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4
Q

What’s a moon

A

A natural satellite made of rock that orbits planets

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5
Q

What’s an asteroid

A

Remnants of bodies that never grew to become planets

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6
Q

What’s a comet

A

Small bodies made of frozen gases, rock and dust

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7
Q

Why do we use telescopes in orbit

A

They’re clearer than those on Earth since gas and dust don’t interfere with the images

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8
Q

What is the gravitational field strength on Earth

A

9.8N/kg

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9
Q

How is the current version of the solar system different to Copernicus

A

Copernicus’ model doesn’t include Neptune and Uranus

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10
Q

How did Galelio’s discovery support Copernicus’ theory

A

He used a telescope to view Jupiter’s moons, he then plotted their movements, showing not everything orbited the Earth

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11
Q

What is gravitational field strength determined by

A

The body’s mass and the radius (bigger mass smaller radius=larger gravitational field strength)

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12
Q

What is meant by elliptical orbits

A

Oval shaped orbits

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13
Q

What are highly elliptical orbit satellites used for

A

Communications in parts of Earth near the poles

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14
Q

How does a satellite always stay in orbit

A

The gravitational force between the Earth and the satellite is always at a 90 degree angle to its movement of direction. It also moves at a constant speed

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15
Q

What happens if a satellite slows down

A

It will crash into the planet it is orbiting

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16
Q

What happens if a satellite speeds up

A

The gravitational attraction between the satellite and Earth will be too weak and it will spin out of orbit

17
Q

Name the sequences a red supergiant goes through

A

Nebula, Protostar, massive main sequence, supernova, black hole

18
Q

Name the sequences a red giant goes through

A

Nebula, protostar, main sequence star, red giant, white dwarf, black dwarf

19
Q

What is a Nebula

A

A cloud of dust and gas

20
Q

How is a protostar made and what is it

A

when a nebula is pulled together by gravity it creates a protostar, gas and dust gets absorbed and the gravity gets stronger. Particles start to collide more often and the kinetic energy of the particles raises the temperature

21
Q

What is a main sequence star

A

When the temperature of a protostar is high enough, hydrogen nuclei fuse to create helium. The outward pressure caused by nuclear fusion and inward pressure

22
Q

How does a red giant turn into a white dwarf

A

When all reactions have taken place the stars gravity pulls in all of its mass, condensing it. It gives off lots of light

23
Q

What does red shift tell us

A

That galaxies are moving away from each other

24
Q

What happens if you move at the same velocity as a source or if you and the source are stationary

A

The frequency will be constant

25
Q

What happens to the wavelength of a moving source

A

The wavelength will become larger as it moves away from you but smaller if it moves towards you

26
Q

What is red shift

A

The increase in wavelength of light due to the source (galaxy) moving away from the observer (Earth)

27
Q

Why does red shift prove that galaxies are moving away

A

Less distant galaxies compared to more distant galaxies have a smaller red shift, the further away a galaxy is from us, the more it will stretch its wavelength to reach us.

28
Q

Why does red shift prove that the universe is expanding

A

The further away a galaxy, the greater its red shift (larger wavelength) and the faster it is moving. This means that the universe is expanding

29
Q

What is the steady state theory

A

The theory that the universe has always existed and has expanded and will continue to expand

30
Q

What is the big bang theory

A

The theory that the universe existed as a tiny point of concentrated energy about 13.5 billion years ago

31
Q

what does the big bang theory tell us

A

A large amount of radiation was released at the start of the universe called comic microwave background radiation

32
Q

What does CMBR stand for

A

Comic microwave background radiation

33
Q

How does CMBR provide evidence for the expansion of the universe

A

The expansion of the universe has stretched this radiation, resulting in microwave background radiation

Physics (7 decks)

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