# forces - Teaching Natural Science Project ```
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Forces are contact forces or field forces.
When two bodies are in contact with each
other, contact forces can result e.g. friction,
twisting, pulling or pushing forces.
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Forces are contact forces or field forces.
Field forces (non-contact forces) work over a
distance e.g. gravity, electrostatic forces and
magnetism.
A force can ...
 make a moving object
stop.
 cause a stationery
object to move.
 change speed of
moving object.
 change direction of
moving object.
 change shape of
object.
 have no effect at all.
Force of attraction that
two bodies have on
each other as a result
of their mass.
1.
The bigger the
mass, the stronger the
force of attraction.
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2.
The smaller the
distance the stronger the
force.
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Weight on Earth
calculated using
formula: F = mg
F = force (gravitation),
m = mass, g =
gravitational
accelleration of
9,8 m/s2.
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Weight of 50 kg person
on Earth = 50 x 9,8
= 490 N
Weight on moon?
50 x 1,6 = 80 N
g on moon = 1,6 m/s2
MASS vs WEIGHT
Mass stays the same, weight
different on earth and moon
 Charge
cannot be created
or destroyed, it can only
be transferred or
distributed.
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Like poles (N and N, or S and S) repel each
other.
Opposite poles (N and S) attract each other.
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We know that the apple probably didn’t fall