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30 Cards in this Set
- Front
- Back
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Why do planets stay in orbit around the sun? |
Due to gravitational attractions |
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Whats centripetal force? |
When any object moving in a circle needs a force towards the centre of the circle. The force is called centripetal force |
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The larger the mass, the gravitational force is lower or greater? |
Greater |
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Why is the orbit time for a plant closer to the sun lower? |
Because the planet travels a shorter distance The planet travels faster due to greater gravitational force |
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Polar orbit? |
Satellites orbit above the north and south poles |
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Most polar orbit satellites take about how many minutes to orbit the earth ? |
90 mins |
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What is polar orbit satellites used for? |
Imaging the earth including short range weather forecasting |
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A geostationary satellite orbits...? |
Above the equator |
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The time for one orbit for geostationary satellite is? |
24 hours |
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Tip |
The nearer a satellite is to earths surface the shorter it's orbit time |
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Equation to find out how much time it took for satellite orbit once? |
Time = distance / speed = 2TTr (r= height ) \ speed |
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Why can't geostationary satellites be too close together? |
Because if they are their signals would overlap due to diffraction |
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Just so you know... |
A ball thrown horizontally from the top of a tower will fall to the ground at the same rate as a ball dropped from the top of the tower |
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Whats trajectory? |
The path object moves |
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The curved trajectory of a projectile is called a _____, and is described as ____ |
Is called a parabola And is described as parabolic |
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Newton theory |
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Forces always occur in? |
Pairs |
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The action and reaction pairs of forces are... |
Are equal in magnitudes (size) Are opposite in direction Act on different objects |
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Cute fact |
Newtons third law |
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Every material is made of...? |
Tiny moving particles with KE |
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The higher the temp the more __ the particles have and faster they move |
Ke |
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The particles collide with the walls of the container, creating a ___, and hence a ____ , on the walls |
Force Pressure |
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Tippy tip |
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Refraction |
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Dispersion? |
The separation of different speeds in a medium and have different refractive indices. This means each colour has different angle of refraction |
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Critical angles |
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Optical fibres are used for...? |
- To carry telephone conversations and computer data as pulse of laser light - in endoscopes to look inside the body without surgery |
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Focal points. The action of convex lens |
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A camera is a box with a lens at one end and film at the other. How does it work...? |
- light from an object passes via the lens and is focused on the film - the size of the image is smaller than the object |
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In a projector, the film is placed closer to the lens than the object is to the camera. How does it work...? |
- light from a bulb passes via the film and the lens and is focused on the screen - the size of the image is larger than the object |
