P8.2 Powering Earth Flashcards

1
Q

2 types of seismic waves

A

P (primary) waves and S (secondary) waves

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2
Q

P waves

A

Longitudinal
Fast (5 km/s)
Can go through solids and liquids

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3
Q

S waves

A

Transverse
Slower (3 km/s)
Can go through solids only

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4
Q

Shadow zones

A

Where one or both types of waves are not detected

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5
Q

Proof that Earth has a liquid outer core

A

Lack of propagation of S waves (shadow zones for S waves are present)

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6
Q

Type of EM radiation stars emit

A

All but mainly visible light

It is a black body meaning it emits and absorbs every wavelength of EM radiation

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7
Q

Relationship between temperature and wavelength

A

The hotter an object, the shorter wavelength peak it has

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8
Q

What colour will hotter stars and cooler stars emit

A

Hotter - blue
Cooler - yellow and red

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9
Q

3 main greenhouse gases

A

Carbon dioxide
Methane
Water vapour

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10
Q

How greenhouse gases are NATURALLY released into the atmosphere

A

Volcanoes (CO2)
Respiration (CO2)
Oceans evaporating (H2O as steam)

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11
Q

How greenhouse gases are released into the atmosphere due to HUMAN ACTIVITY

A

Combustion of fossil fuels (CO2)
Deforestation (CO2)
Extensive cattle farming (CH4)

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12
Q

Explain greenhouse effect

A

Short wavelength visible light passes through the atmosphere mainly unobstructed
Some reflects from clouds
Earth absorbs the radiation and heats up
It is warm enough to emit only long wavelength infrared radiation
Infrared radiation is absorbed by greenhouse gases in the atmosphere
This heats the atmosphere
IR radiation absorbed by the atmosphere is then re-emitted in all directions
Some is emitted back to the Earth’s surface

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13
Q

Force which works on all planets around the sun

A

Centripetal force
This force always acts towards the centre of the orbit
The force/acceleration must be at right angles to the direction of movement
The velocity is changing because the direction is changing, but the speed is constant

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14
Q

Why are planets closer to sun able to move faster than objects away from sun

A

Since they are closer, they have a larger force of gravity working on it as it’s closer to the sun and likewise with the opposite according to the inverse square law

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15
Q

Geostationary orbit satellites

A

Take 24 hours to orbit
Remain in fixed position above Earth’s surface
Orbit above Earth’s equator
Used for satellite communication

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16
Q

Low polar orbit satellite

A

Have a very short time period (90 mins)
Travel pole to pole
Can observe every part of the planet over time
Relatively close to the Earth’s surface
Used as weather, mapping and spy satellites

17
Q

Life cycle of a stars (formation)

A

Interstellar gas clouds (nebulae) collapse due to gravity, producing a protostar
When a star is large and hot enough, it starts to fuse hydrogen into helium in its core
This is when a star is stable: the main sequence star

18
Q

Life cycle of a stars (death of small stars like the sun)

A

Smaller stars, like the sun, expand and cool to become red giant stars
They lose their outer gas layers to produce planetary nebula.
Centre of the red giant star collapses and forms a small and hot white dwarf star
Cools to form a brown dwarf then a black dwarf

19
Q

Life cycle of a stars (death of larger stars)

A

Larger stars expand and cool and become red supergiant stars
Centre of the star continues to collapse until it explodes in a supernova explosion
Remaining star then collapses to form a neutron star or a black hole if the star is that large
Black holes have such a large mass and large gravity that not even light can escape

20
Q

Evidence of the Big Bang

A

Doppler effect
Cosmic microwave background (CMB)

21
Q

Doppler effect

A

Light from all far away galaxies is red shifted
Shows that the galaxies are moving away from us
The further away a galaxy is, the more its light is red shifted and the faster it is moving away from us
Therefore, if you put it in reverse, it would mean that the universe was much closer together at one small dense point

22
Q

Cosmic microwave background radiation (CMBR)

A

In the 1960s, scientists discovered that microwave radiation was coming from all directions of the universe
This radiation is believed to be the heat radiation that is left over from the original explosion
This radiation had a high frequency but as it has been stretched over time, it now has a frequency in the microwave region of the EM spectrum