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P1
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- 1How old is the solar system?5000 thousand million years old
- 2How was the solar system formed?It was formed over a very long period from big clouds of dust and gas. One of these clouds started to get squeezed slightly, particles moved closer together, this was when gravity took over and caused everything to collapse on itself. IN the centre formed a protostar - high temperatures resulted in fusion in which hydrogen nuclei joined to make helium.
- 3What is the oldest type of rock?Meteorites - these are rocks that have crashed into earth
- 4What are asteroids and comets?They are made up of stuff leftover from the formation of the solar system
- 5What are asteroids?These are rocks that didn't from planets, made of smallish lumps of rubble and rock and stayed in between Mars and Jupiter.
- 6What are comets?They are balls of rock, dust and ice which orbit the sun in very elongated ellipses.
- 7What happens when a comet passes near the sun?Its ice melts, leaving behind a bright trail of gas a debris. Millions of kilometres long - can be seen from earth
- 8How do we find the distance of nearby stars?We use parallax, this is where astronomers take pictures of the sky six months apart and the apparent movement of the star lets you work out how far away it is. Stars further away move less, movement is small to detect.
- 9What is another method?Is to measure its brightness. They measure the amount of radiation certain types of stars emit, and by examining how bright they look, they can measure how far away it is.
- 10What problems are caused by the atmosphere and light pollution?The atmosphere absorbs quite a lot of light, so some light from space does not reach us. Light pollution, street lights, make it hard to see dim objects. This is why the Hubble space telescope was put in space.
- 11How fast does light in a vacuum travel?300,000 km per second
- 12Why do we see stars and galaxies as they were in the past?This is because only now is the light becoming to reach us
- 13How long does light from the sun take to reach us?8 minutes
- 14What is redshift?Galaxies moving away from us, the wavelength of light emitted changes - it shifts to the red side of the spectrum. The greater the redshift, the faster is moving away. This proves that the whole universe is expanding.
- 15What is the theory of the big bang?All matter and energy in the universe must have been compressed into a very small space, this exploded and started to expand, this expansion is still going on now.
- 16What is the big crunch?if theres enough mass compared to how fast the galaxies are currently moving, the universe will eventually stop expanding and begin contracting
- 17What happens if theres not enough mass?The universe will never stop expanding
- 18How do rocks provide a record that the Earth changed?The grand canyons colorado river has been eroded, leaving an impressive slash through the middle of Arizona. This erosion happens everywhere (cliffs eroded by the sea) something else must be happening otherwise all mountains would have been worn down. This means that something is making new rock (evidence of this is easy) for example when lava from volcanoes sets. Fossils also provide evidence (the animals and plants couldn't have dug themselves into the middle of rocks) the rocks had to have been built around them. From these rocks the age of the earth can be estimated. Oldest rocks were made around 4 thousand million years ago. So earth has been around for at least this long.
- 19How are rocks recycled?Particles eroded from existing rock get washed into the sea and settle as sediment. Over time they get crushed and form sedimentary rocks. These can get pushed to the surface or can descend into the heat and pressure inside the earth. If they descend the structure of the rock can change completely (due to the heat and pressure) they can melt. If they are pushed up to the surface they cycle just starts again - very powerful forces to push rocks up or down. Evidence that rock has been squeezed and folded.
- 20What is Wegener's theory of continental drift?His theory was that once all the continents fitted together and over time moved apart, this offered evidence to way similar fossils were found in different continents.
- 213 pieces of evidence which proves his theory correct?Same fossils found in different continents
Shape of continents fit together
Mountain belts - 22Why was his theory rejected at first?- He was a meteorologist and not a geologist
- His theory explained things that couldn't be explain by the 'land bridge' theory
- His explanation of the continents drifting wasnt convincing (wasnt detectable) he said it was caused by tidal forces and the earth rotation which other geologists proved was impossible - 23Why was his theory accepted in the end?In the 1950s investigated and found that the mid-atlantic ridge and found evidence that magma rises up through the sea floor, solidifies and forms underwater mountain that are roughly symmetrical either side of the ridge. This suggested that the sea floor was spreading (few cm's a year). Even better evidence proved that the continents were moving apart due to the magnetic orientation of the rocks. As liquid magma erupts, iron particles in the rock tend to align themselves with the earth magnetic field and as it cools they set in position. Every half million years or so the earth magnetic field swaps in direction so rocks begin to face the opposite way [(alternate polarity)(seafloor spreading)]. This was convincing evidence that the sea floor was being created and continents were moving apart.
- 24What is the crust of the earth?This is the bit we live on and is very thin (20m); two types 1. continental crust (land) and 2. oceanic crust (sea)
- 25What is the earth mantle?This is below the crust and has the properties of a solid but can flow very slowly, heat from the core and heat from radiative decay in the mantle cause it to flow in convectional currents.
- 26What is the earth core?This is the centre of the earth, which we think is mainly made of iron and nickel
- 27What are tectonic plates?They hold the mantle and crust together and float like big rafts on the mantle.
- 28What causes seafloor spreading?Its the movement of the mantle
- 29What are the two types of seismic waves?P waves and S waves
- 30What are P waves?They can travel through liquid and solids.
Travel faster than S waves
They are also longintudinal - 31What are S waves?Only travel through solids
Slower than P waves
They are transverse waves. - 32What happens when seismic waves hit reach a boundary.Some waves will be reflected. Waves also change speed dependant on the density of the mantle and core (this changes). Most of the time the waves speed changes gradually, resulting in a curved path but when they change suddenly the speed changes abruptly and the path has a kink.
- 33What do seismic graphs tell you?- About half way through the Earth, P waves change direction abruptly - indicates theres a sudden change in properties.
- The fact the S waves are not detected in the cores shadow tells us that the outer core is liquid.
- P waves travel slightly faster through the middle of the core - strongly suggests that theres a solid inner core
- S waves don't travel through the mantle - shows that its a solid - 34What are waves and what do they do?Waves are just disturbances that are caused by a vibrating source and they carry and transfer energy in the direction that the wave travels, but does not transfer matter.
- 35What is the amplitude of a wave?The amplitude is the distance from the middle to the top of the wave (or bottom), the larger the amplitude the more energy the wave has.
- 36What is wavelength?Wavelength is the length of a full cycle of the wave,e.g. from crest to crest
- 37What is frequency?The number of complete waves passing a certain point per second, measured in Herts (Hz)
- 38What is speed?How fast it goes
- 39What are transverse waves?Transverse waves are waves that travel at a 90* angle to the direction of travel of the wave.
- 40What are longitudinal waves?The vibrations are in the same direction as the wave is travelling.
- 41How do you calculate wave speed?Wave speed (m/s) = frequency (Hz) x wavelength (m)
OR
'v=fλ' - 42QUESTION: A wave has a frequency of 92.2 x 10^6 Hz - Find its wavelength (speed of all Em waves is 3x10^8so wavelength = wave speed / frequency
- 3x10^8/92.2x10^6= 3.25m
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- Fichas sobre P1, creado por charlie croxford el 17/05/2014.
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- charlie croxford
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