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7th Grade
Unit 6:
Forces and Motion
Lesson 1:
Unbalanced Forces and
Motion
Vocabulary of Instruction:
Accelerate
• Speed up or
to increase
the speed
of an object
(to push the
gas on a
car).
Newton’s First Law of Motion
• An object
remains at
rest or in
motion with
a constant
velocity
unless
acted upon
by an
external
force.
Inertia
• The tendency
of an object to
stay at rest or
to continue to
move at the
same velocity
(speed plus
direction),
unless acted on
by an external
force.
State of Motion
• An object that is
moving from one
place to another
and is defined by
its velocity (the
speed with a
direction).
Decelerate
• To slow down
the speed or
velocity of an
object
(applying the
brakes to a
car).
Kinetic
• Moving or causing motion of an object.
Kinetic Friction
• Is when an object
slides on a surface.
Static
• Is usually used
to describe
objects at rest
or forces in
equilibrium.
Static Friction
• Is a force between
two stationary
surfaces that inhibits
motion. (Static
Friction is always
greater than kinetic
friction).
Equilibrium
• Is when two
forces find a
state of
balance
where no
more change
occurs.
Magnitude
• The size of a force.
Friction
• Is a force that
appears
whenever one
surface rubs
against another
and that impedes
motion (when an
object moves
through water, air,
or any other
liquid or gas.