Gravity%20and%20Space

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Gravity and Space

• W Richards
• The Weald School

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Gravity
Gravity is an attractive force that affects
anything with mass
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Gravity
Gravity depends on 2 things
1) The mass of the objects
2) The distance between them
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Weight vs. Mass
Earths Gravitational Field Strength is 10N/kg.
In other words, a 1kg mass is pulled downwards by
a force of 10N.
Weight Mass x Gravitational Field Strength (in
N) (in kg) (in N/kg) To
Remember Weight measured in Newtons Mass
measured in kilograms

1. What is the weight on Earth of a book with mass
   2kg?
2. What is the weight on Earth of an apple with mass
   100g?
3. Dave weighs 700N. What is his mass?
4. On the moon the gravitational field strength is
   1.6N/kg. What will Dave weigh if he stands on
   the moon?

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Rockets
When a rocket flies away from Earth the force
needed to keep it accelerating decreases
Words gravity, smaller, large, lighter
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Natural Satellites
These planets are all satellites of the sun
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
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Artificial Satellites
Artificial satellites have been around for 50
years and have 3 main uses
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
Words the same, atmosphere, low polar, TV, day