space

• what is our galaxy?


  milky way
• what is the structure of the solar system?

  the sun, planets, moons, dwarf planets, asteroids, comets
• what is the sun?

  • largest object in solar system
  • huge gravitational field with other objects orbit
• what is the order of planets from closet to the sun to furthest away?

  Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• what happens as the distance from the sun increases?

  • temperature decreases
  • time taken to orbit sun increases
• what are moons?

  • natural satellites
  • amount of moons vary per planet
• what are dwarf planets?

  • gravitational field isnt strong enough to clear neighbourhood
  • e.g. pluto and ceres
• what are asteroids?

  • orbit sun in highly elliptical orbits which are oval
  • take millions of years to complete
  • made of metals and rocky material
  • many in the asteroid belt between mars and jupiter, and many in the kuiper belt beyond neptune
• what are comets?

  • made of rocky material, dust, ice
  • when approaching sun, it vaporises and produces a distinctive tail
• when was the solar system formed?

  • 4.6 billion years ago
  • nebula which collapsed under its own gravity, transferring gravitational potential energy to kinetic energy in its particles
  • as nebula collapsed it became denser and rotated more rapidly
  • collisions between particles caused kinetic energy to be transferred as internal energy and thermal energy
  • core of nebula began to form a hot, dense protostar
• what happens when suns core becomes hot / dense enough, and nuclear fusion reactions start?

  • hydrogen nuclei join together to form helium nuclei
  • energy’s transferred by radiation
• what is orbital motion?

  Motion of an object around another object under the influence of gravity.
• what happens if the satellite is moving too quickly?

  gravitational attraction between earth and satellite is too weak to keep in orbit so the satellite will move off into space which occurs around 11200 m/s
• what happens if the satellite is moving too slowly?

  gravitational attraction will be too strong, and the satellite will back to earth usually at the below 7600 m/s
• what happens if the satellites speed is right?

  travel around a fixed path
• where do artificial satellites travel?

  in one of two orbits: polar or geostationary
• What happens to the direction of an object moving in a circle at constant speed?

  Its direction constantly changes
• Why does an object moving in a circle experience a change in velocity?

  Because its direction is constantly changing
• What type of quantity is velocity?

  Vector quantity
• What results from a change in velocity?

  Acceleration
• Can an object moving in a circle be accelerating if its speed is constant?

  Yes, because its direction changes
• What is required for an object to accelerate?

  A resultant force must act on it
• What is the resultant force acting on an object moving in a circle?

  Centripetal force
• In which direction does the centripetal force act for an object in circular motion?

  Towards the middle of the circle
• What provides the centripetal force needed for planets and satellites in orbit?

  Gravitational attraction
• What is the relationship between centripetal force and circular motion?

  • Centripetal force is necessary for circular motion
  • It acts towards the center of the circle
  • Keeps objects like planets and satellites in orbit
• What happens to gravitational attraction as distance increases?

  It decreases with distance
• How does distance affect the force of gravity between two objects?

  Closer objects have a stronger gravitational force
• What occurs when the gravitational force between two objects is greater?

  A greater acceleration will occur
• How does greater acceleration affect an object's velocity?

  It causes a greater change in velocity
• What is the relationship between orbit size and speed of objects?

  Objects in small orbits travel faster
• What is the relationship between gravitational force, acceleration, and velocity in orbits?

  • Gravitational attraction decreases with distance
  • Greater gravitational force leads to greater acceleration
  • Greater acceleration results in greater change in velocity
  • Smaller orbits result in faster travel speeds
• what do polar orbits do

  • take satellites over earths poles which travel very close to earth and very high speeds
• what do geostationary orbits do?

  • geostationary satellites take 24 hours to orbit earth so it appears to remain in the same part of the sky when viewed from the ground
  • much higher than polar orbits so satellites travel more slowly
• what is the life cycle of a star similar to the size of our sun?

  1. protostar
  2. main sequence star
  3. red giant star
  4. white dwarf
  5. black dwarf
• what is the life cycle of for stars much bigger than our sun?

  1. protostar
  2. main sequence star
  3. red super giant star
  4. supernova
  5. black hole or neutron star
• what is a nebula?

  • a cloud of dust and gas
  • mostly composed of hydrogen
  • gravity will pull the dust and gas together
• what is a protostar?

  as mass falls together it gets hot. a star is formed when its hot enough for hydrogen nuclei to fuse together to make helium. fusion process releases energy which keeps the core of the star hot.
• what main sequence star?

  force of gravity holding the star together is balanced by higher pressure due to high temperature. gravitational attraction tends to collapse star. radiation pressure from fusion reactions tends to expand star. forces caused by gravitational attraction and fusion energy are balanced
• what stage is our sun at?

  main sequence star