Transcript Phases of the Moon ppt File - Watford Grammar School for Boys

9J Gravity and space
9J Gravity and space
Gravity
Old and new ideas
Space travel and
satellites
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9J Gravity and space
Gravity
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9J Keeping your feet on the ground
Wherever you are on Earth,
the same force keeps your
feet on the ground.
It holds our atmosphere
around us and keeps the
oceans on the Earth.
What is it?
You remember – it’s...
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9J Feel the force
Gravity is a force that acts between two objects.
It depends on two things.
How does gravity depend on mass and distance?
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9J Galactic Gnome Inc.
Galactic Gnome Inc. exports garden gnomes to planets
across the Universe.
What do these gnomes weigh on Earth?
Remember that on Earth
1 kg weighs 10 N.
gravitational
weight = mass ×
field strength
(in N) (in kg)
(in N/kg)
THE
BIG DAN
1.1 kg
DIGBY
0.4 kg
BOB COMMANDER
0.1 kg
0.5 kg
gravitational field
= 10 N/kg
strength on Earth
The company pays tax when each gnome reaches its new
home planet. For every newton of weight they pay 1 Galacto.
Get ready to work out some tax bills!
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9J Galactic Gnome Inc.
Work out the tax due for each gnome.
1 Galacto per newton
gnome
weight on
Earth (N)
export to planet…
Big Dan
11
Sirius 7
3
33
Big Dan
11
Betelgeuse 3
1
11
0.5 
2
gravity
compared
with Earth’s
tax due
(Galacto)
Digby
4
Kessell System 5
Bob
1
Nebula 2
8
8
The
Commander
5
Nebula 2
8
40
Does a gnome’s mass change on its new planet?
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9J The NASA diet?
An astronaut’s weight changes on a journey to the Moon.
Match these weights to the astronaut’s position.
0N
730 N
750 N
125 N
launch pad on
Earth
750 N
low Earth
orbit
730 N
on surface
of Moon
in space between
Earth and Moon
Distances not to scale
125 N
0N
What happens at C?
Why is C nearer the Moon than the Earth?
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9J Are you on solid ground?
True or False?
1. A
2.
3.
4.
5.
6.
7.
Gravity
Magnetism
Weight
The
6 Nmass
force
weight
is the
measured
a
of
ofis
force
gravity
aon
force
the
body
Earth
that
opposite
of
on
changes,
ingravity
attracts
would
the
newtons.
surface
force
weigh
acting
two
buttoits
bodies.
of
gravity.
only
on
weight
the
a 1body
Moon
N stays
onnear
is
thethe
the Earth.
lower
Moon.
same
than
whenon
the
Earth
forcebecause
of gravity
the
changes.
Moon has a smaller
mass.
FALSE! Gravity
TRUE!
Gravity
Gravity
Your
Wrong
weight
depends
is
isway
aholding
force,
is
aa measure
upon
and
you
the
and
forces
weight
of
mass
the
how
are
Earth
of
changes
measured
much
anof the
Magnetism
isround!
different
force
from
The
Moon’s
gravity
isThe
only
one-sixth
object.
in
together
the
because
newtons.
Earth
The
even
isitsmaller
attracting
depends
now!
theboth
you
on
object,
the
(and
gravitational
the
you
smaller
areact at
gravity.
But
they
are
forces
that
Earth’s.
its
attracting
gravitational
The
it!).mass
pull.stays the same because it
aforce.
distance.
depends on how much ‘stuff’ there is in the
body.
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9J Gravity and space
Old and new ideas
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9J The old ones are the best?
Thousands of years ago people moved these enormous
rocks hundreds of miles to make Stonehenge.
They must have been
very clever engineers.
Would you know how
to do it?
But their ideas of the
world and space were
much more limited.
What did a Stonehenge-builder believe about the Earth
and the Sun?
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9J Stonehenge, the Sun and stars
For Stonehenge-builders the Earth
was flat.
The Sun was a giant fire and the Moon was… well,
we don’t know exactly. We do know that these ancient
people could predict eclipses with great accuracy.
How clever do you think the Stonehenge-builders were?
Were their ideas sensible for their time?
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9J The Greeks have it...
The Greeks were probably the first people to study the
Earth and the Sun scientifically.
Match each idea about the Earth to the correct person.
It’s a sphere at
the centre of
the Universe.
It’s a sphere
rotating
It’s
a discaround
a hugeinfire.
floating
water.
It’s a sphere
rotating around a
huge fire.
Pythagoras
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Thales
It’s a sphere thatIt’s
turns
on
It’s
disc
a sphere
thataturns
It’s a sphere
its axis every 24 on
hours
and every
floating
its axis
24 in
at the centre
moves around the
Sun and moves
water.
hours
of the
with all the other around
planets.the Sun with all
Universe.
the other planets.
Aristotle Aristarchus
9J Towards a modern view
After the Greeks our view of the Universe hardly
changed for another thousand years.
Ideas built up slowly.
Tycho
Copernicus
Galileo
Kepler
Brache
The
TheEarth
planets
and
orbit
planets
the
move
Sun,
orbit
orbit
but
around
thethe
Sun.
Sun
Sun.
theThe
Sun
and
Moon
Moonin
orbits
orbit
ellipses.
the
the Earth.
Earth.
Jupiter also has moons
orbiting it.
Why was it so hard to work out how the Universe works?
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9J Quiz
How much do you know about our Universe?
1. The Moon orbits the Earth in…
a) a circle
b) an ellipse
c) a spaceship.
2. Jupiter’s gravitational pull is…
a) larger than Earth’s
b) smaller than Earth’s
c) the same as Earth’s.
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9J Quiz
3. The Sun is at the centre of the…
a) Earth
b) Universe
c) Solar System.
4. The stars and planets stay in their places because of…
a) glue
b) gravity
c) speed.
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9J Gravity and space
Space travel and
satellites
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9J Space words
Match each word to its correct meaning.
gravity
solar
orbit
lunar
ellipse
geostationary
word
meaning
orbit
the path a satellite takes around a body
ellipse
a ‘flattened circle’ shape
gravity
force that pulls two bodies towards each other
geostationary
describes a satellite that is always above the same
point on the Earth’s surface
lunar
to do with the Moon
solar
to do with the Sun
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9J Working outwards from the Sun
Label the planets in order, starting with Mercury nearest the Sun.
Earth
Mercury
Jupiter
Saturn
Neptune
Uranus
Mars
Pluto
Sun
Venus
Distances not to scale
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9J Let’s stay together
Why do planets orbit the Sun? It’s the result of gravity.
What will happen if you switch the gravity off?
Explain how gravity keeps the planet orbiting the Sun.
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9J Satellite links
So theWhat’s
Moon is
a a
satellite
of the Earth.
satellite?
There are also pieces of broken
Anything
spaceship and other debris in
that’s in orbit
orbit, that have been trapped by
around aput artificial
Scientists
the Earth’s gravitational field.
larger body.
satellites
in orbit round
the Earth too.
Artificial satellites have different orbits.
Can you name three types of orbit?
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9J Orbits
The three types of satellite orbit are shown below.
geostationary
keeps
the
A
low-Earth
orbit orbit
isover
closer
Satellites
travelling
the North
satellite
above
the
same
point
to
the
Earth’s
surface.
and
South
poles
have
polar
orbits.
on the Earth.
N N
N
S
SS
How long does a satellite in a geostationary orbit take to
orbit the Earth?
Which satellite has the shortest orbit time? Why?
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9J What are satellites for?
Weather satellites take
pictures of weather systems
moving across the globe to
help meteorologists predict
the weather.
Communications satellites
relay messages from mobile
phones and television stations
around the world.
Research satellites
measure things like the
concentration of ozone or the
temperature of the Earth’s
oceans.
Survey satellites look down
on the Earth and find out
about anything from mineral
deposits to the size of the
Sahara desert.
The Hubble telescope is a satellite orbiting the Earth that
looks out at stars and galaxies in the very distant Universe.
Why does the Hubble telescope take better
pictures than telescopes on Earth?
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9J Satellite images
This picture of volcanoes in Ecuador was taken from a
satellite.
What might people use images like this for?
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9J Satellite images for research
The ‘hole’ in the ozone layer as seen by a satellite.
The purple areas show the thinnest part of the ozone layer.
This picture was created by putting together a number of
separate images.
What has caused the hole in the ozone layer?
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9J Weather forecasting
You can see the clouds in this weather satellite image. By
putting together a sequence of images you can see the
weather moving across the UK.
How do you think satellite pictures help
meteorologists forecast the weather?
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