Gravitational field is not strong enough to clear its orbit
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Asteroids
-Smaller objects made of metals and rocks
-Elliptical orbit (oval shape around sun)
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Comets
-Small objects made of rock, dust and ice
-Vaporizes to gas as it approaches the sun and products tail
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Calculating gravity
weight (N) = mass (Kg) x gravity field strength (n/kg)
W
----
MxG
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Early ideas of the solar system
(geocentric)
Based on what could be seen with the naked eye
Earth at the centre of the solar system, explanations of the planets became very complex
Plotemy (AD 100-168)
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Early ideas of the solar system
(heliocentric)
Nicolas Copernicus (1473-1543)
Changed model to sun in the centre
Advanced telescopes back up that this is the correct idea
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Orbital motion
-Gravity provides force for stable orbit
-object must be travelling at a correct speed to stay in orbit
-too slow falls to what it is orbiting
-too fast it leaves orbit
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Orbiting Earth
-too quickly (over 11,200 m/s) gravitational attraction between earth and satellite is too weak and will leave orbit and drift to space
-too slowly (under 7,600 m/s) gravitational attraction is too strong and the satellite falls back to earth
-in between
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Orbit + constant speed
-moving in circle with constant speed; direction constantly changes so change in velocity(vector quantity); so there is acceleration despite constant speed
-object accelerates when resultant force acts on it
-circle; resultant force is centripetal force t
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Orbits + changing speed
-gravitational attraction decreases with distance
-closer object→ increase G force→ greater acceleration → faster object moves
-smaller orbits travel faster
-to increase orbit speed radius of orbit must decrease to maintain stable orbit
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Polar orbit
Satellites go over Earths poles
Travel close to Earth and at very high speed (8000 m/s)
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Geostationary orbit
Satellite takes 24hrs to orbit earth so appear stationary from earth
Travel much further from earth and much slower
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