Download Forces and Motion

Newton’s
rd
3
Law of Motion
Unit Standards
5.P.5A.1 Use mathematical and computational thinking to describe and predict
the motion of an object (including position, direction, and speed).
5.P.5A.2 Develop and use models to explain how the amount or type of force
(contact and non-contact) affects the motion of an object.
5.P.5A.3 Plan and conduct controlled scientific investigations to test the effects
of balanced and unbalanced forces on the rate and direction of motion
of objects.
5.P.5A.4 Analyze and interpret data to describe how a change of force, a change
of mass, or friction affects the motion of an object.
5.P.5A.5 Design and test possible devices or solutions that reduce the effects of
friction on the motion of an object.
What is Newton’s Third Law?
• When one object pushes on a second object,
the second pushes back on the first with the
same strength.
What is Newton’s Third Law?
• Action forcethe push of the
first object on
the second
object
• Reacting forcethe push of the
second object
back on the
first object
What is Newton’s Third Law?
• Newton’s Third Law of Motion- All forces
occur in pairs, and these two forces are equal
in strength and opposite in direction.
What is Newton’s Third Law?
• More commonly people say “for every action
there is an opposite but equal reaction.”
What is Newton’s Third Law?
• It is important to remember that action and reaction
forces are not balanced forces. This is because action
and reaction forces always act on separate objects.
What is Newton’s Third Law?
• When you sit in a
chair, your weight
is pushing down
on the chair. A
reaction force
from the chair
pushes back up on
you. This reaction
force is what you
feel as your
weight.
What is Newton’s Third Law?
• When you are
falling the force of
gravity is still acting
upon you. You do
not feel gravity
because there is
nothing providing a
reaction force. This
is why you feel
“weightless” when
you are in a free fall.