Junior cycle science physics the earth and beyond
-
Upload
theresa-lowry-lehnen -
Category
Education
-
view
276 -
download
0
description
Transcript of Junior cycle science physics the earth and beyond
12/04/23Junior Cycle Junior Cycle Physics Physics
The Earth and Beyond
Edited and Reproduced by
Theresa Lowry-LehnenRGN, BSc (Hon’s) Specialist Clinical Practitioner (Nursing), Dip Counselling, Dip Adv Psychotherapy,
BSc (Hon’s) Clinical Science, PGCE (QTS) , H. Dip. Ed, MEd, Emotional Intelligence (Level 9) MHS Accredited
12/04/23There are nine planets in our solar There are nine planets in our solar system:system:
Mercury
MarsJupiter
Saturn
Neptune
Uranus
Pluto
VenusEarth
My Very Easy Method Just Speeds Up Naming
Planets
12/04/23
We see planets and the moon because they reflect sunlight:
The sun is different – it produces its own light.
12/04/23The Earth orbits the sun…The Earth orbits the sun………every year (365 every year (365 11//44
days)days)
Ellipse
12/04/23
The Earth is kept in orbit by 2 things…The Earth is kept in orbit by 2 things…
GravityGravity
…and by the fact that it is moving at a high velocity
12/04/23
The Earth spins on an axis…
Because of this spin the sun and stars appear to
“move” across the sky…
12/04/23
GravityGravityGravity is an attractive force that affects anything with mass:
Note that this force goes both ways – the Earth
is attracted to us.
12/04/23Gravity on different Gravity on different
planets:planets:
Jupiter – gravitational field strength = 25N/Kg
Earth – gravitational field strength = 9.8N/Kg
12/04/23More information on gravityMore information on gravity
F
F/9
F/4
If you double the distance the
gravitational force divides by 4…
If you triple the distance the force
divides by 9…
The amount of gravity attracting an object decreases the further out the object is…
12/04/23How much of the moon we see How much of the moon we see depends on where the moon is in depends on where the moon is in
its orbit:its orbit:
Appearance:
12/04/23
Appearance:
12/04/23
Appearance:
12/04/23CometsCometsComets are balls of dust and frozen gas. They have very elliptical orbits:
As the comet approaches the sun gases evaporate from it, forming a “tail”. This tail always faces AWAY from the sun.
12/04/23
Artificial SatellitesArtificial Satellites
Geostationary orbits:
Low polar orbits:
12/04/23Artificial SatellitesArtificial Satellites
1) Observation (e.g. Hubble Space Telescope) – these are in orbit high above the Earth and can observe the universe without interference by the ____________
2) Communications (e.g. ___, phone, car “SatNav” systems) – these satellites are in “geostationary” orbits. This means that the satellite always stays above ____ ____ point on the Earth and takes a ______ to complete an orbit
3) Monitoring (e.g. weather, spy satellites) – these satellites have a “___ _____” orbit and may scan around the Earth several times a day
Artificial satellites have been around for 50 years and have 3 main uses:
Words – the same, atmosphere, low polar, TV, day
12/04/23Solar systems, galaxies and the Solar systems, galaxies and the UniverseUniverse
OUR SUN is one of millions of stars that orbit the centre of…
THE MILKY WAY, which is one of a billion galaxies that orbit AND move away from the centre of…
THE UNIVERSE
(Basically, everything in the universe orbits around something else)
12/04/23Quiz..Quiz..1) What is the sixth planet in the solar system?
2) What is the biggest planet in the solar system?
3) Name 2 differences between stars and planets
4) How long does the Earth take to orbit the sun?
5) What 2 things keeps the Earth in orbit?
6) Why does Mars take longer to orbit the sun than Earth?
7) How long does the moon take to orbit the Earth?
8) Would the acceleration due to gravity on Mars be bigger or smaller than on the Earth and why?
9) Which hemisphere is Britain in?
12/04/23Quiz..Quiz..
10)What is the name of the line that divides the two hemispheres?
11)How long does the Earth take to rotate?
12)Where does the sun rise and set?
13)If you double the distance between two objects what happens to the force of gravity between them?
14)What shape describes the shape of a comet’s orbit?
15)What is a comet made up of?
16)Where does a comet’s tail point and why?
17)What keeps stars in orbit around the centre of a galaxy?
12/04/23
Searching for ETSearching for ETIn any scientific enquiry you have to OBTAIN some evidence and then ANALYSE it. Consider searching for extra-terrestrial life on Mars:
OBTAINING EVIDENCE
•Fly to Mars yourself (takes ages)
•Use robots to bring back samples (not very reliable)
•Use robots to take pictures and send them back (also not very reliable)
ANALYSING EVIDENCE
•Use microscopes to search for fossilised remains inside the samples
•Place the sample in a container and monitor changes in the environment due to living organisms being present in the sample
12/04/23
Evidence about the Evidence about the origins of the universe…origins of the universe…
12/04/23
Source of light “Spectra
”
12/04/23
If you pass the light through a gas something different is seen…
helium
Some wavelengths of light are absorbed by
the gas – an “absorption spectrum”.
12/04/23
After
helium
If the light source is moving away the absorption spectra look a little different…
helium
Before
12/04/23The absorption lines have all been “shifted” towards the longer wavelength end (red end)…
After
BeforeThis is called red
shift. The faster the light source moves the further its light will be “shifted”
A similar effect happens with sound – this is called “The
Doppler Effect”Hear Doppler Effect
12/04/23Light from different stars and from the edge of the universe also shows this “red-shift”. This suggests that everything in the universe is moving away from a single point.
This is the BIG BANG theory
12/04/23
Red shift summaryRed shift summaryLight from other galaxies has a longer _________ than expected. This shows that these galaxies are moving ____ from us very quickly. This effect is seen to a greater extent in galaxies that are _______ away from us. This indicates that the further away the galaxy is, the ______ it is moving.
This evidence seems to suggest that everything in the universe is moving away from a single point, and that this process started around 15 _____ years ago. This is the ____ ________ Theory.
Words to use – faster, away, big bang, billion, wavelength, further
12/04/23
The Life Cycle of a StarThe Life Cycle of a Star
12/04/23
Stage 1: NebulaeStage 1: Nebulae
A nebulae is a collection of dust, gas and rock.
Some examples of nebulae…
12/04/23
Dark nebula
12/04/23
Emission nebula
12/04/23
Planetary nebula
12/04/23
Reflection nebula
12/04/23
Gravity will slowly pull these particles together…
As they move inwards their gravitational potential energy is converted into heat and a PROTOSTAR is formed
Stage 2: ProtostarStage 2: Protostar
12/04/23Stage 3: Main SequenceStage 3: Main Sequence
Our sun is an example of a main sequence star – it’s in the middle of a 10 billion year life
span
In a main sequence star the forces of attraction pulling the particles inwards are _________ by forces acting outwards due to the huge __________ inside the star.
Stars are basically ________ reactors that use _______ as a fuel. During its main sequence a star will release energy by converting hydrogen and helium (light elements) into _________ elements.
Words – heavier, balanced, hydrogen, nuclear, temperatures
12/04/23
Eventually the hydrogen and helium will run out. When this happens the star will become colder and redder and start to swell…
If the star is relatively small (like our sun) the star
will become a RED GIANT
If the star is big (at least 4 times the size
of our sun) it will become a RED SUPERGIANT
Stage 4: Red GiantStage 4: Red Giant
12/04/23
What happens at this point depends on the size of the star…
1) For SMALL stars the red giant will collapse under its own gravity and form a very dense white dwarf:
Stage 5: The DeathStage 5: The Death
White dwarf
Black dwarf
Red giant
12/04/232) If the star was a RED SUPERGIANT it will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas.
AfterBefore
This explosion is called a
SUPERNOVA
12/04/23The dust and gas on the outside of the supernova are thrown away by the explosion and the remaining core turns into a NEUTRON STAR.
If the star is big enough it could become a BLACK HOLE.
12/04/23
The dust and gas thrown out by a supernova can be used to form a new star…
Stage 6: Second generation Stage 6: Second generation starsstars
Our sun is believed to be a “______ ______ star” – this is because it contains some __________ elements along with hydrogen and ________. These heavier elements would have been the products of a previous star that have been thrown out by a ________. These heavier elements are also found on planets, indicating that they might have been made from remains of previous _______ as well.
Words – helium, heavier, second generation, stars, supernova