1.)
Newton’s First Law -
“Every object continues in a state of rest
or of uniform speed in a straight line unless acted on by a nonzero net force.”
Another way to say this is that an object
at motion with stay in motion and an object at rest will stay at rest unless
acted on by an outside force. The prime example of this law is where someone
has set up a dinner ware set and pulls the table cloth out from underneath it.
The dishes stay in their restful state because their inertia is greater than
the force acted on it.
This same concept applies to objects in
motion. An object at motion with continue to move without turning or gaining
speed. This was the concept demonstrated
by our hovercraft lab in the beginning of the year. Although, this concept is mainly evident in
space, we were able to recreate a friction-less environment by keeping the
craft floating above the ground.
2.)
Newton’s Second Law –
We learned all about Newton's Second Law
and its behavior towards objects that may have an unbalanced force on them in
the air. Newton's second law states that the acceleration of an object is
dependent upon two variables - the net force acting upon the object and the
mass of the object. The acceleration of an object depends directly upon the net
force acting upon the object, and inversely upon the mass of the object. So as
force acting on an increase, the acceleration of that object increases. As the
mass of the object increases, the acceleration of that object decreases.
In other words acceleration is directly
proportionate to force and inversely proportionate to mass. The equation below
uses Fnet which can also be determined by mass times acceleration.
A = Fnet/m
3.)
Newton’s Third Law of Motion
Newton's third law of motion states that,
"for every action there is an equal but opposite reaction." In the
beginning of this lesson, we start to understand the concept of forces and
interactions. We grasp a concept of forces such as pushing or pulling, but
realize that no force or interaction occurs alone. Every force is part of an
interaction between one thing and another. For example when a boxer uses his
force to punch a large punching bag, the first force on the bag is from the
boxer's fist, which causes the bag to dent. However, the punching bag also
applies a force back on the boxer's fist. If the boxer was to punch a lighter
tissue that was in midair, then the tissue could only exert how much force was
exerted on it. This is why an interaction requires a pair of forces action on
two separate objects.
After understanding this concept, we then
moved to learn about Newton's Third Law of Motion and how it cooperated with
action and reaction pairs. Newton's Third Law is summarized by stating,
"whenever one object exerts a force on a second object, the second object
exerts an equal and opposite force on the first." But how do we grasp this
concept using demonstrations. For example, when you walk, you interact with the
floor. You push against the floor and the floor pushes against you. These pairs
of forces are the same. So when stating "YOU PUSH on FLOOR" (This
being the action) "FLOOR PUSHES on YOU" (This being the reaction)
Next, this concept goes further in depth, which helps you understand how
actions and reactions work when two object differentiate in mass. The book
states, "As strange as it may seem, a falling object pulls upward on
Earth with as much force as Earth pulls
downward on the object. The resulting acceleration of the falling object is
evident, while the upward accelration of the Earth is too small to
detect." When am apple is falling out of a tree the apple is pulling the
Earth upward as much as the Earth is pulling the apple downward. Therefore
"EARTH PUSHES APPLE DOWN" = "APPLE PUSHES EARTH UP." And to
an extent we learn about how force is related to mass and acceleration
proportionately with the demonstration of a cannon and a cannonball. When using
the formula (F/m) = a, we know that if you have a smaller force then you are
going to have a greater acceleration, and if you have a smaller acceleration
you are going to have a greater force. We see this when demonstration a cannon
firing. The force exerted against the recoiling cannon is just as great as the
force that drives the cannonball inside the barrel. During the class we also
played a game of tug of war that helped us understand the concept of forces
applied. The guys competed against the girls in the game of tug of war, with
one exception the guys were wearing socks on the hardwood floor. Anyways, the
girls one because they were able to put more force on the ground which allowed
them to pull harder.
4.)
Rotational Inertia–
The definition of tangential speed is the
direction of the motion tangent to the circumference of the circle. We learned
that tangential and linear speed can be used interchangeably. Rotational speed,
however, involves the number of rotations or revolutions per unit of time. We
used these two definitions with many everyday problems and scenarios that
correlate appropriately. The real life exercise we used was the merry go round
question. All of the fine physics students in Ms. Lawrence's class embarked on
a journey to the outside world, were we lined up and locked arms. We learned
now that even though the inside center point of the rotating line, trying to
represent the merry go round, the students who were on the outside of the line
were moving at a faster speed in order to cover the same ground as the students
on the inside. This is due to the fact that they have the same rotational speed
because they are connected, but have different tangential speeds because the
outside needs to cover more distance than the inside.
5.)
Law of Gravity and Free Fall –
This animation demonstrates that when an
two objects are in free fall they hit the ground at the same time disregarding
the mass difference of each object. It also demonstrates that when two objects
are dropped and are encountered with air resistance they most likely will not
hit the ground at the same time. This for many reasons. One reason being that
each object may have a different surface area that causes more or less air
resistance. Another reason is that they will have different mass and have a
stronger force of gravity pulling them towards the Earth.
6.)
Law of Conservation of Momentum
Momentum is simply inertia in motion. Or
can also be defined as Momentum = (Mass x Velocity) We learned that a moving
object can have a large momentum if either its mass or velocity are large or if
both its mass and its velocity are large. One example we used in class was
comparing a truck and a small car and seeing how their mass and speed compared
to their momentum proportionately. Next, we learned about momentum. We learned
that if the momentum of an object changes. then either the mass or the velocity
or both changes. This is shown by the quantity force times time interval, or,
Impulse = Ft. The greater the impulse exerted on something, the greater will be the change in momentum. So
therefor, Impulse = change in momentum. One example that really helped me grasp
this concept was the example that showed that if a boxer "rolled with the
punches then the impulse would be less."
This was shown as (little F)(BIG t)= (Big F)(little t) This is where the
force over a greater time period would be less as opposed to the force being
greater over a shorter time period. Then, we moved into the concept of objects
bouncing. We learned that when an object hits something it has an initial
impact and if it is not absorbed, has another impact that makes the object
bounce off. This creates two forces on the object if the force is not absorbed.
The demonstration where Mrs. Lawrence was in the rolling chair and threw and
caught a heavy object and she continued to move backwards really helped me
understand this more in depth. The final thing we looked at in this unit was
the conservation of momentum.
From Newton's second law, we learned that
to accelerate an object, a net force must be applied to it. This was generally
the same in this chapter except written and explained differently. If we wished
to change the momentum we would have to change the impulse. The demonstration
the Mrs. Lawrence used where two cue balls were hit together and one stopped
and the other kept moving helped me understand in real life terms of how
momentum is transferred.
7.)
Law of Conservation of Mass
This Law states that matter cannot be
created nor destroyed only transformed. The mass is transformed when the
transformation is preformed and the matter stays the same.
8.)
Law of Conservation of Electric Charge
When dealing with electric current
it is important to understand how conductors and insulators work. A conductor is a when any material that make
the electrons “loose” and transfer energy between it. A good conductor for
example, is any type of metal. Electrical wires in circuits consist of metal to
allow the electrons to flow through the wire and bring energy to the source. On
the outside of the wire is a coating that is an insulator. An insulator is an
item that does not allow electrons to pass through it.
9.)
Coulomb’s Law
Coulomb’s Law deals with an electric charge
over a distance.
“Coulomb's law states that the electrical force between two
charged objects is directly proportional to the product of the quantity of
charge on the objects and inversely proportional to the square of the
separation distance between the two objects.”
10.) Ohm's Law
Ohm's law states that “the current through a conductor
between two points is directly proportional to the potential difference across
the two points.”
V=I/R
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