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Space Physics
The Universe
Circular motion and orbital speed: Space physics: Physics: GCSE (9:1)
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Created by
Harry Parker
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Cards (20)
Velocity
The
speed
of an object in a
given direction
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Acceleration
The rate of
change
of
speed
or
velocity
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Resultant force
A
single force
that
replaces
all the
forces
acting on an
object
and causes an object to
accelerate
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Circular motion
When an object follows a
circular path
, usually at a
constant speed
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Velocity (object in circular motion)
The
velocity
of an object travelling in a
circle
is
changing
(even when its speed is
constant
) because its
direction
is
changing
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Acceleration (object in circular motion)
An object travelling in a circle is
accelerating
because its
direction
(and therefore its
velocity
) is
changing
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Centripetal force
The
resultant force
that causes the
acceleration
of an object travelling in a
circle
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Direction of centripetal force
The
centripetal force
always acts
towards
the
centre
of a
circle
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Gravitational attraction
Provides the centripetal force that keeps satellites in orbit around planets and planets in orbit around stars
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How the force of gravity between two objects varies with distance
The
closer
the two objects are, the
stronger
force of gravity between them
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Effect of the force of on velocity
The
greater
the
force
of
gravity
between two objects, the
greater acceleration
and therefore the
velocity
so the object will
move faster
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Effect of orbit size on the speed of an satellite
Objects in
small
orbits travel
faster
than objects in
large
orbits
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Polar orbit
Satellites
in a
polar orbit
travel over the
Earth’s poles
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Height above the Earth for a satellite in a polar orbit
The satellites travel as low as
200 km
above
sea level
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Speed of a satellite in a polar orbit
The satellites have a
small
orbit so travel very
fast
, at nearly
8,000
m/s
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Geostationary orbit
Satellites in a geostationary orbit take
24
hours to orbit the
Earth
so appear to remain above the same point on the
Earth's surface
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Height above the Earth for a satellite in a geostationary orbit
The satellites travel around
36,000
km above sea level
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Speed of a satellite in a geostationary orbit
The satellites have a
large
orbit so travel
slower
than a satellite in a
polar
orbit, at around
3,000
m/s
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Relationship between orbital speed of a satellite and its height above the Earth's surface
The
further
from the
Earth's surface
a satellite is, the
slower
it
travels
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Relationship between
orbital
speed of
planet
and its
distance from
the Sun
The further
from
the Sun
a
planet
is,
the slower
it
travels
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