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Description
Flashcards by harry.vinall, updated more than 1 year ago
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Created by harry.vinall
over 10 years ago
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| Question | Answer |
| Name and describe the five main objects in the solar system (putting them in order of size) | Planets- spherical objects orbiting the sun in near circular orbits. Dwarf planets- same as planets but much smaller. Asteroids- Lumpy rocks in near-circular orbits Comets- lumps of ice and dust elongated orbits that stretch far from the sun and may pass very close to it. Moons- balls of rock that orbit a planet in near circular orbits |
| How far is one light year? | 9.5 million million kilometers (9.5 trillion Km) |
| Name and describe two ways to measure distances to stars | 1. Star brightness. Use the real brightnesses of two star (found by assuming similar types of stars have the same brightness), the relative brightnesses (how bright they appear to be) and how far away one star is. This provides an estimate of the distance. 2) Parallax - works by comparing the apparent position of a star (from earth) compared to stars in the background at different points of the earths orbit. The difference in angle is used to measure distance. However this can't be used for stars that are further away as the angle becomes to small to measure. |
| How are elements formed in stars? | Through fusion. Nuclei are jammed so hard together they are crushed together to make a heavier nucleus, meaning a different element is formed. 94% of all atoms in sun are hydrogen. When hydrogen nuclei fuse the form helium and give out heat and light energy, which is the source of light and heat we receive from the Sun. Fusion in the sun creates all the elements up to iron. Heavier elements are formed in supernovas (when stars explode) and all then spread as dust throughout the galaxy. |
| Explain Redshift | Light originating from stars or galaxies moving away from us has a longer wavelength. Red light has a longer wavelength than all other visible light so light from these sources appears redder than from similar sources in our own galaxy. This is called redshift and is evidence that the universe is expanding. The greater the redshift the faster the galaxy is moving away from us. This is detected using a spectrometer. |
| How do scientists believe the Universe was formed and what evidence is there for this? | Scientists believe the universe began 14 billion years ago when a rapid expansion occurred in which matter and energy were flung out- the big bang. Evidence for this includes light that suggests the universe has been expanding for 14 billion years and cosmic background radiation, which is an 'echo' of the initial explosion. |
| How do scientists believe the Sun and our solar system was formed and what evidence is there for this? | About 5 billion years ago our Sun formed at the centre of a huge swirling cloud of gases that collapsed in on itself. A few million years later, the remaining matter swirling around the Sun formed the planets, asteroids and moons. The Earth was formed about 4.5 billion years ago. These ideas have formulated by observing how other new planetary systems form and dating meteorites formed when the solar system was created. Additionally since all objects in the solar system orbit in the same direction it's logical to conclude the whole system formed at the same time. |
| Outline the different possibilities for the future of the Universe | The future of the universe depends on whether the mass of the Universe is in relation to the 'critical' amount needed to balance the expansion of the universe. If it is above critical mass, the universe will reach a maximum size and then start to shrink. If it is equal to critical mass the Universe will simply reach a fixed size. If it is below a critical mass the universe will expand forever. |
| Give four reasons for erosion and name (and explain) the process that occurs when products of erosion are deposited | Moving water, glaciers (moving ice sheets), the wind, gravity (landslides). Sedimentation occurs when eroded material is deposited. Over millions of years sediments are crushed together to form sedimentary rock. |
| Outline the key ideas and evidence for Wegener's theory of continental drift | That the continents used to be joined together and had drifted apart over millions of years. He thought this because the shape of the continents looked as if they could interlock, similar fossils and rocks were founded on different continents, mountain chains made from similar rocks appeared on the edges of different continents. However this theory was rejected. |
| What is 'the spreading seafloor' and what can we learn from it? | The earths core heats rocks in the mantle, as some are hotter than others convection occurs. This causes sections of the Earth's crust to be forced apart making the seafloor spread. The gap left is then filled with fresh rock from the mantle, this spreading forms underwater mountains called oceanic ridges. Evidence for this theory can be found in the magnetisation of the sea floor. The Earths magnetic field changes every couple of million years. Every time rock comes to the surface it is magnetised by the Earth's magnetic field, so the fact that different sections of the ocean are magnetised in different directions is evidence that the seafloor is spreading. |
| Explain plate tectonics | Solid tectonic plates float on top of semi-solid rocks below the crust. The place where two plates meet are called plate boundaries. They move very slowly either pulling apart (causing volcanoes), pushing together (causing mountains) or sliding past each other (causing earthquakes). Fold mountains occur where tectonic plates of similar densities push together, lifting and folding the land. The plates move because of convectional currents in the Earths mantle. |
| What are the main stages if the rock cycle? | Mountains weathered and fragments of rock broken off; these are transported and then deposited on the seabed as sediment; at plate boundaries one plate can be forced beneath another, if an oceanic plate is forced below land, sediments are dragged down as well; as the plate moves deeper the rock melts and becomes magma; pressure can cause magma to rise and either solidify in rock beneath land or escapes as a volcanic eruption to form new mountains. |
| Describe the Earth's structure | Crust: solid rock about 30km thick Mantle: semi-solid rok about 2900Km thick Outer core: thin later of liquid nickel and iron about 2200Km thick Inner core: solid nickel and iron about 1250Km thick |
| What are S and P waves? | Seismic waves produced in an earthquake. P-waves are longitudinal (like sound) travel through solid and liquid are faster than S-waves. S-waves are transverse (like light) and only travel through liquid. By detecting S and P waves scientists can infer things about the Earth's structure. |
| Write the equation for wave motion | distance= wave speed x time |
| What is an oscilloscope and what can it tell us? | A machine that displays waves on a screen. By looking at the amplitude of a sound wave we can determine the volume (bigger amplitude= louder) and by looking at the wavelength we can determine pitch (shorter= higher) |
| Write the wave equation and explain the different components | wave speed (m/s)= frequency (hertz, Hz) x wavelength (meters). Frequency is the number of waves passing a point every second. The wavelength is the length of each wave (e.g. from crest to crest). |
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