PD6 EARTH SPACE AND RADIATION REVISION TOPICS

The Following topics are the MAIN areas of study for this unit for both Foundation and higher level candidates. It is advised that these areas should be revised in more depth.

AREAS OF STUDY
    Solar System
    Motion and Gravity
    Distances in Space
    Big Bang
    Life Of stars
    Red Shift
    Basic Radiaition
    Half Life
    Effects and Uses of Radiation

    Self teach module

    Back to main Physics menu

    1) SOLAR SYSTEM
  1. Order of the nine planets

    2. The Solar System
  2. Rotation of the earth to get day and night
  3. Tilt of the earth the reason we get seasons
  4. Which planet is biggest/smallest, hottest,/coldest, has most moons etc
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    2)MOTION AND GRAVITY
    Acceleration = Change in Velocity ÷ Time
    Acc = D D ÷ t
    m/s2 m/s sec


    Acceleration = Force ÷ Mass
    Acc = F ÷ M
    m/s2 (N) (kg)

  1. Unless there is an opposing force an object moves in a stright line indefinately Block carrys on right

  2. an object moves in the direction of the largest forceblock moves right
  3. an object stays still if the forces acting on it are balancedblock stays still OR if there are no forces acting on it


    4. GRAVITY
  4. Affects weight (on Earth 1kg=10N)

  5. Size of gravity depends on size and density of object (e.g Earth has more gravity than the moon)
  6. Gravity is responsible for centripetal force that keeps planet orbiting sun and the moon orbiting the Earth
  7. Makes all objects accelerate towards earth at same rate (10m/s2)
  8. Heavier objects have higher terminal velocity see the previous unit for more information
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    3)RELATIVE DISTANCES IN SPACE

Know the relative distances (in terms of which is biggest/ smallest distance)
  1. the planets to the sun,
  2. the moon to the earth,
  3. the sun to it’s nearest neighbours

    4. LINK Scale model of the solar system

  4. size of galaxy compared to solar system
  5. size of galaxy
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    4)BIG BANG

    Click here to view slide showBig Bang theory of the Big Bang theory(power point needed)
  1. that the big bang is on of the most likely theories that might explain how the universe began
  2. Evidence that the big bang happened
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    5)LIFE OF A STAR
  1. How a star is born (as gravity makes the hydrogen particles fuse)
  2. How long a star stays as a main sequence star (depending on size/ illuminosity)
  3. How a star "dies" (depending on it’s size)
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    6)DOPPLER EFFECT AND RED SHIFT

Change in frequency as the detector moves towards or away from wave

  1. Doppler effect- sound (going towards sound wave frequency/pitch increases)

e.g. an Ambulance moving towards you sounds high pitched:-

If the Java applet below does not load you need a Java platform (an add on for windows explorer)
Download it here

b) Red shift- light (going toward light wave frequency increases so light looks bluer) eg stars moving away from each other appear redder
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    7)BASIC RADIATION
Click here for more information on radiation

Some Elements have isotopes that are unstable they are "radio active and might emit

  1. Alpha Radiation (a ) Helium nucleus emitted from nucleus of unstable isotope

    2. Not very penetrative thick card can stop it vapour trails can be detected

  2. Beta Radiation (b ) electron emitted from nucleus of radioactive atom

    3. Medium penetrative qualities can be stopped by a thick piece of metal

  3. Gamma Radiation(c ) Electromagnetic wave released from atom

    4. Highly penetrative thick lead needed to stop it

  4. Can be detected by Geiger counter
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    8)HALF LIFE

    Defined as the time it takes for a radio active material to fall to half it’s original value

    Imagine a radio active material with a half life of 2 years. If it has a radioactive count of 1024/sec when it is brand new this is what happens to it
    Time New 2 Years 4 years 6 years 8 years 10 years 12 years 14 years
    Radio active count 1024 512 256 128 64 32 16 8

    this java script shows what happens to the radioactive particles inside the material as it "decays"
    watch the "speed" at which the material decays to begin with. The decay then slows down as time goes on

    If the Java applet below does not load you need a Java platform (an add on for windows explorer)
    Download it here

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    9)EFFECTS OF RADIATION
USES OF RADIATION

Chemotherapy

Irradiating food

Measuring thickness of metals/check for metal defects

Nuclear power

Sterilising of surgical equipment


EFFECTS OF RADIATION

Effects vary according to level of dose and time exposed to it

Headaches/sickness loss of hair are exposure symptoms

Also linked to some cancers

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