Earth and Space

Earth and Space

1. FORCES

   • Forces are a push, pull or a twist.
     • Altitude is the height of an object
   • A contact force is a force that acts only with the physical contact between 2 objects
   • A non-contact force is a force that can be applied to an object without any physical contact between the object and another
   • Gravitational Field is a field of force surrounding a body of mass
     • Air preasure is the force exerted by air, by any surface in contact with it.
       • Air density is the mass per unit volume of air.

2. GRAVITY

   • A force of attraction between 2 objects. It is a non-contact pulling force that attracts an object to downwards to the centre of the earh
   • Mass is a measure of how much matter in in an object
   • Weight is the measure of the force of gravity on an object
   • WEIGHT = MASS X GRAVITY (w=mxg)

3. Creation of the Earth

   • THE RAINBOW SERPENT (aboriginals), BIG BANG THEORY (scientists)
   • There are many viewpoints of the creation of the earth.

4. OUR SOLAR SYSTEM

   • Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
   • Objects Galileo could see: Stars, Moons, Neptune, Saturns Rings
   • Geocentric model: stationary earth lies in center and all other planets orbit it.
     • Heliocentric model: Sun lies in center and other planets orbit it.
   • Earth both rotates and revolves, around the sun and its own axis.
   • ALL orbiting planters travel along elliptical paths
   • Some of the technilogical advances of the telescope have contributed to our current model of the Solar System as we have been able to see objects in space.

5. EARTH

   • The earth rotates around its axis once every 24 hours. As the earth moves along its orbit, the orientation of its axis changes with respect to the sun. This is what creates day ad night.
   • As the earth revolves around the sun, it also revolvesaround its axis. This is what creates seasons. For example, the Southern Hemisphere - around december is tilted toward the su, causing summer.
     • LAYERS OF THE EARTH:
     • Crust: Hard, solid layer. Mantle: Thick, semi-solid layer. Hotter and denser than crust. Outer Core: Liquid layer made of metals. Inner Core: solid layer made of metals
   • Allignment of sun, moon and earth in Lunar eclipse:
     • Biopshere: Everything living.
       • Atmosphere: Cotains ALL gases on earth.
         • Hydrosphere: Contains ALL water on the earth
           • Lithosphere: Rigid layer of NON-LIVING things.

6. NATURAL AND MAN-MADE RESOURCES

   • Man-made: Net (nylon), plastic (plastic), synthetic cloth (raincoat)
   • Natural: Paper (wood), balloon (rubber), leather (leather), chair (wood), spoon (metal), coal, silk, fur
   • A resource is a material with properties that make it useful.
     • Non-renewable resources such as gas can be good for jobs and the econmony HOWEVER can: affect environmeny, affect health from gases in air, ruin land, pollution, harmful levels of sir pollution, accidents//danger