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28 Cards in this Set
- Front
- Back
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What do planets reflect? |
Sunlight |
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What do planets orbit? How? |
The sun, in ellipses |
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What are ellipses? |
Almost circular paths |
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What's the difference between stars and planets? |
Stars are HUGE, VERY HOT, and VERY FAR AWAY. They give out lots of light. Planets are SMALLER, REFLECT sunlight, MUCH CLOSER TO US. |
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How old do we think the Solar System is? |
5 THOUSAND MILLION YEARS OLD. |
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How was the solar system formed? |
From big clouds of gas and dust over a very long period of time. |
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What happens during fusion? |
Hydrogen nuclei join together to make helium. |
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How old are meteorites? |
4500 million years old |
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What are asteroids and comets made of? What are comets? |
Stuff left over from the formation of the Solar System. Balls of rock, dust and ice which orbit the sun in very elongated ellipses. |
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What do rocks provide? |
A record of changes in the Earth. |
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What did Alfred Wegener hypothesise? |
Africa and South America had previously been one continent which then split. |
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What evidence supported Wegener's theory? |
Rocks on different continents, and similar fossils in both South Africa and South America. |
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What is the Earth's surface made of? |
Tectonic plates. |
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How are volcanoes formed? |
Tectonic plates meet, producing magma which rises. |
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How are mountains formed? |
Plates crash into each other. |
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What do P-waves travel through? |
Solids and Liquids. |
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What do S-waves travel through? |
Solids. |
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When do seismic waves curve? |
With increasing depth. |
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When do seismic waves change speed? |
As the properties (e.g density) of the mantle and core change. - Causes waves to change direction - refraction |
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What do waves have? |
Amplitude, wavelength, frequency and speed. |
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What are waves? |
Disturbances caused by a vibrating source. |
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What is the amplitude? |
The distance from rest position to the crest or trough. the bigger the amplitude, the more energy the wave has. |
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What is the wavelength? |
The length of a full cycle of a wave, e.g. from crest to crest. |
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What is the frequency? |
The number of complete waves passing a certain point per second. OR The number of waves produced by a source each second. |
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What is frequency measured in? |
Hertz (Hz) |
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What is a longitudinal wave? |
Vibrations are along the same direction as the wave is travelling. |
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What is a transverse wave? |
Vibrations are at 90° to the direction of travel of the wave. |
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What is the equation for wave speed? |
Wave speed=Frquency X Wavelength |
