Space - paper 2 Flashcards

To revise space (Paper 2)

1
Q

Describe our solar system

A

the Sun, plus the eight planets and the dwarf planets that orbit around the Sun. Natural satellites, the moons that orbit planets, are also part of the solar system.

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2
Q

State the name of our galaxy

A

The milky way

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3
Q

How was the sun formed

A

The Sun was formed from a cloud of dust and gas (nebula) pulled together by gravitational attraction. This cloud heats up until fusion can start.

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4
Q

What reaction takes places in all stars

A

Nuclear fusion

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5
Q

Why are stars stable?

A

usion reactions lead to an equilibrium between the gravitational collapse of a star and the expansion of a star due to fusion energy.

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6
Q

Describe the life cycle of a small star, like the sun

A
Nebula
Protostar
Main sequence star
Red Giant
White dwarf
Back dwarf
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7
Q

Describe the life cycle of a large star

A
Nebula
Protostar
Main sequence star
Red Super Giant
Supernova
Neutron star or Black hole
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8
Q

Which was the first element created by the big bang

A

Hydrogen nuclei (protons)

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9
Q

How were the light elements made

A

Fusion in stars

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10
Q

How were the heavy elements made

A

Fusion in supernovas

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11
Q

How were all the elements distributed through the universe

A

By supernovas

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12
Q

What forces keeps planets in orbit around a star

A

Gravity

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13
Q

What is a stable orbit?

A

A stable orbit is one in which the satellite’s speed is just right - it will not fly off into space (too fast) or spiral into the Earth (too slow) but will travel around a fixed path.

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14
Q

What is the relationship between orbit radius and speed.

A

The gravitational attraction between two objects decreases with distance. This means that the closer the two objects are to each other, the stronger the force of gravity between them.
This means that objects in small orbits travel faster than objects in large orbits. In order to change orbital speed, an object must change the radius of its orbit at the same time, to maintain a stable orbit.

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15
Q

Define red shift

A

There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength.

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16
Q

What evidence does red shift provide?

A

The observed red-shift provides evidence that space itself (the universe) is expanding and supports the Big Bang theory.

17
Q

What is the big bang theory

A

The Big Bang theory suggests that the universe began from a very small region that was extremely hot and dense.

18
Q

How can an object in orbit be travelling at a constant speed but still be accelerating

A

the object is constantly changing direction,
so the velocity must be changing
A change in velocity is an acceleration
The object is always accelerating towards the centre of the orbit

19
Q

How many stars are in our solar system?

A

One - the sun

20
Q

What are natural satellites?

A

The moons that orbit planets

21
Q

What type of star is the sun?

A

A main sequence star

22
Q

How is a red giant formed?

A

Hydrogen runs out and the star initially collapses as gravity is now the stronger force.
After a star collapses, the star heats up enough for helium to fuse and it expands (radiation pressure > gravity)

23
Q

How is a white dwarf formed?

A

The red giant starts to run out of its fuel (Helium) Gravity is bigger than radiation pressure so the star collapses

24
Q

Define the doppler effect

A

The change in frequency of a wave, caused by relative motion between the source of the wave and the observer

25
Q

Why is the pitch higher when a car is moving towards you?

A

Wavelength is decreased so frequency is increased

26
Q

Why is the pitch higher when a car is moving away from you?

A

Wavelength increases so frequency has decreased

27
Q

Describe the universe before the big bang

A

Hot and dense