# Force and Motion by xiaoyounan

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```									Force and Motion
Sir Isaac Newton (1642 - 1727)
   His ideas are built upon
the ideas of Galileo.
Newton's three Laws of
Motion are general,
universal LAWS that
explain a wide range of
situations. (Newton also
invented Calculus and
in Optics, including
inventing the reflecting
telescope).
   Observe elephants and
feathers, automobiles
and skydivers to learn
air resistance, free-fall,
inertia, and Newton's
laws of motion.
Motion
   According to Newton's first law, an object in
motion continues in motion with the same speed
and in the same direction unless acted upon by an
unbalanced force. It is the natural tendency of
objects to keep on doing what they're doing. All
objects resist changes in their state of motion. In
the absence of an unbalanced force, an object in
motion will maintain this state of motion. This is
often called the law of inertia.
Force
   A force is a push or pull upon an object
resulting from the object's interaction with
another object. Whenever there is an
interaction between two objects, there is a
force acting on each of the objects. When
the interaction ceases, the two objects no
longer experience a force. Forces only
exist as a result of an interaction.
Types of Forces
Contact Forces          Action-at-a-Distance Forces

Frictional Force        Gravitational Force

Tensional Force         Electrical Force

Normal Force            Magnetic Force

Air Resistance Force

Applied Force

Spring Force
   Speed - how fast
an object is
moving.“
   Velocity – speed in
a given direction
   Acceleration - the
rate at which an
object changes its
velocity
   Sports announcers will occasionally say that a
person is accelerating if he/she is moving fast.
Yet acceleration has nothing to do with going
fast. A person can be moving very fast, and
still not be accelerating. Acceleration has to do
with changing how fast an object is moving. If
an object is not changing its velocity, then the
object is not accelerating.
   If the forces acting
upon an object are
balanced, then the
object
   A is not moving.
   B. is moving with a
constant velocity.
   C. both A and B.
   D. accelerating.
If the forces acting upon an object are
balanced, then the object

   A is not moving.
   B. is moving with a constant velocity.
   C. both A and B.
   D. accelerating.
MASS
   The mass of an object (measured in kg) will be the same no
matter where in the universe that object is located. Mass is
never altered by location, the pull of gravity, speed or even
the existent of other forces.
   For example, a 2-kg object will have a mass of 2 kg whether
it is located on Earth, on the moon, or on Jupiter; its mass
will be 2 kg whether it is moving or not and its mass will be
2 kg whether it is being pushed or not.
WEIGHT
   On the other hand, the weight of an
object will vary according to where in the
universe the object is. Weight depends
upon which planet is exerting the force
and the distance the object is from the
planet. Weight is equivalent to the force of
gravity.
Falling
   Falling with Air
Resistance
    As an object falls
through air, it usually
encounters some degree
of air resistance. Air
resistance is the result of
collisions of the object's
molecules.
   Suppose that an elephant and a feather
are dropped off a very tall building from
the same height at the same time.
Suppose also that air resistance could be
eliminated such that neither the elephant
nor the feather would experience any air
drag during the course of their fall. Which
object - the elephant or the feather - will
hit the ground first? The
 "Doesn'ta massive object
accelerate at a greater rate
than a less massive object?".
Elephant and Feather - Air
Resistance


Suppose that an elephant and a feather
are dropped off a very tall building from
the same height at the same time. We will
assume the realistic situation that both
feather and elephant encounter air
resistance. Which object - the elephant or
the feather - will hit the ground first?
Words to know!
 motion               unbalanced

 reference   point forces
 speed            average speed

 force            constant speed

 balanced forces  velocity

 acceleration
The table and graph both present
position at certain times.
Time/s   Distance
from
start/m
0        0
2        20
4        40
6        60
8        80
Did we cover these
objectives?
What is the relationship
between force and motion?
Why is it important to
understand the relationship
between
force and motion?
What mathematical skills can a
science student use to collect
and analyze data?
Identify and describe the
changes in position, direction of
motion, and speed of an object
when acted upon by force.
Demonstrate that changes in
motion can be measured and
graphically represented.
How can changes in motion
be measured and graphed?
What do forces do to the
position, direction, or speed of
an object?
Works Cited
   http://www.math-
science.sfasu.edu/physics101/Newton%27
sLaws.html
   http://www.oldsci.eiu.edu/physics/DDavis/
1350/05Laws/ToC.html
   http://www.physicsclassroom.com/mmedi
a/newtlaws/cci.html

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