Forces & Motion
Big Ideas
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Every force is part of an interaction between
two objects
Forces are pushes and pulls that can be contact
or non-contact forces
Motion is described relative to something else
(point of reference)
A change in motion is due to unbalanced forces
No change in motion and an object at rest are
due to balanced forces
Forces
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Force: a push or pull that causes an object to
accelerate in the direction of the force
Contact Forces: pushes and pulls that result
from direct touching of objects
Friction: the force of two surfaces in contact
with each other
Non-contact Forces: pushes and pulls that result
without the direct touching of objects acting at a
distance
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Magnetic attraction: a force that pulls objects
with opposite poles towards on another
Magnetic repulsion: a force that pushed objects
with the same poles away from one another
Gravitational force: a force that pulls objects
toward each other. This force acts between all
objects.
Identify the following as Contact or
Non-Contact Forces
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A foot kicking a soccer
ball
An apple falling off a
tree
A paper clip sliding
towards a magnet
A bat stricking a baseball
Two magnets pushing
apart from one another
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The moon orbiting the
Earth
A compass needle
turning North
A hand pushing an
object
Shoes rubbing against
the floor
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Contact Forces
Friction
Drag (air resistance)
Physical Contact with an
object
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Non-Contact Forces
Gravity
Magnetism
Magnetism
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http://player.discoveryeducation.com/index.cf
m?guidAssetId=FF1B9001-1689-4319-B062F13E2EB2F7C6&blnFromSearch=1&productc
ode=US
Create a Cartoon
Today you are making a cartoon strip. Your
cartoon strip should be about a super hero who
uses the power of forces to save people. Your
cartoon should have eight sections that include
examples of:
 3 Contact Forces
 3 Non-Contact Forces
 Labels for each force
 Color
Balanced & Unbalanced Forces
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http://player.discoveryeducation.com/index.cf
m?guidAssetId=04269900-C995-41A9-8DFCB16580A3CCE8&blnFromSearch=1&productc
ode=US
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Net force: the combination of all forces acting on an
object. This determines if an object moves and in which
direction
Non-zero net force: when forces act in the same
direction the net force is found by adding the strengths
of the individual forces. When forces act in opposite
directions, they combine by subtraction.
Zero net force: when the combined forces are zero.
The motion of an object will not change. (If it is at rest
it stays at rest, if it is in motion it stays in motion)
Balanced force: equal forces acting on one object in
opposite directions. These do not change the object’s
motion
Unbalanced forces: whenever a net force acts on an
object. This can cause it to start moving, stop moving
or change direction
Unbalanced Forces
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http://www.mansfieldct.org/schools/mms/staf
f/hand/lawsunbalancedforce.htm