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#Post#: 355--------------------------------------------------
Physics
DIR By: Red
Date: April 22, 2013, 3:01 pm
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This thread is dedicated to an explanation of what is listed in
the California Standards for Physics. I'll try to give as good
of an explanation for some things as possible, but for many
topics, I might have to link readers to an external resource. I
can only remember so much.
(\ (\
( -.-)
(> )> *~gomen~*
TTTT
Physics
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Motion and Forces
1. Newton’s laws predict the motion of most objects. As a
basis for understanding this
concept:
a. Students know how to solve problems that involve constant
speed and average
speed.
b. Students know that when forces are balanced, no acceleration
occurs; thus an
object continues to move at a constant speed or stays at rest
(Newton’s first law).
c. Students know how to apply the law F=ma to solve
one-dimensional motion
problems that involve constant forces (Newton’s second
law).
d. Students know that when one object exerts a force on a second
object, the second
object always exerts a force of equal magnitude and in the
opposite direction
(Newton’s third law).
e. Students know the relationship between the universal law of
gravitation and the
effect of gravity on an object at the surface of Earth.
f. Students know applying a force to an object perpendicular to
the direction of its
motion causes the object to change direction but not speed
(e.g., Earth’s gravita
tional force causes a satellite in a circular orbit to change
direction but not speed).
g. Students know circular motion requires the application of a
constant force directed
toward the center of the circle.
h.* Students know Newton’s laws are not exact but provide
very good approxima
tions unless an object is moving close to the speed of light or
is small enough that
quantum effects are important.
i.* Students know how to solve two-dimensional trajectory
problems.
j.* Students know how to resolve two-dimensional vectors into
their components and
calculate the magnitude and direction of a vector from its
components.
k.* Students know how to solve two-dimensional problems
involving balanced forces
(statics).
l.* Students know how to solve problems in circular motion by
using the formula for
centripetal acceleration in the following form: a=v2/r.
m.* Students know how to solve problems involving the forces
between two electric
charges at a distance (Coulomb’s law) or the forces
between two masses at a
distance (universal gravitation).
Conservation of Energy and Momentum
2. The laws of conservation of energy and momentum provide a way
to predict and
describe the movement of objects. As a basis for understanding
this concept:
a. Students know how to calculate kinetic energy by using the
formula E=(1/2)mv2.
b. Students know how to calculate changes in gravitational
potential energy near
Earth by using the formula: <change in potential energy> = mgh
(h is the change in
the elevation).
c. Students know how to solve problems involving conservation of
energy in simple
systems, such as falling objects.
d. Students know how to calculate momentum as the product mv.
e. Students know momentum is a separately conserved quantity
different from
energy.
f. Students know an unbalanced force on an object produces a
change in its momen
tum.
g. Students know how to solve problems involving elastic and
inelastic collisions
in one dimension by using the principles of conservation of
momentum and
energy.
h.* Students know how to solve problems involving conservation
of energy in simple
systems with various sources of potential energy, such as
capacitors and springs.
Heat and Thermodynamics
3. Energy cannot be created or destroyed, although in many
processes energy is trans
ferred to the environment as heat. As a basis for understanding
this concept:
a. Students know heat flow and work are two forms of energy
transfer between
systems.
b. Students know that the work done by a heat engine that is
working in a cycle is
the difference between the heat flow into the engine at high
temperature and the
heat flow out at a lower temperature (first law of
thermodynamics) and that this
is an example of the law of conservation of energy.
c. Students know the internal energy of an object includes the
energy of random
motion of the object’s atoms and molecules, often referred
to as thermal energy.
The greater the temperature of the object, the greater the
energy of motion of the
atoms and molecules that make up the object.
d. Students know that most processes tend to decrease the order
of a system over
time and that energy levels are eventually distributed
uniformly.
e. Students know that entropy is a quantity that measures the
order or disorder of a
system and that this quantity is larger for a more disordered
system.
f.* Students know the statement “Entropy tends to
increase” is a law of statistical
probability that governs all closed systems (second law of
thermodynamics).
g.* Students know how to solve problems involving heat flow,
work, and efficiency in
a heat engine and know that all real engines lose some heat to
their surround
ings.
Waves
4. Waves have characteristic properties that do not depend on
the type of wave. As a
basis for understanding this concept:
a. Students know waves carry energy from one place to another.
b. Students know how to identify transverse and longitudinal
waves in mechanical
media, such as springs and ropes, and on the earth (seismic
waves).
c. Students know how to solve problems involving wavelength,
frequency, and
wave speed.
d. Students know sound is a longitudinal wave whose speed
depends on the proper
ties of the medium in which it propagates.
e. Students know radio waves, light, and X-rays are different
wavelength bands in
the spectrum of electromagnetic waves whose speed in a vacuum is
approxi
mately 3 x 108m/s (186,000 miles/second).
f. Students know how to identify the characteristic properties
of waves: interference
(beats), diffraction, refraction, Doppler effect, and
polarization.
Electric and Magnetic Phenomena
5. Electric and magnetic phenomena are related and have many
practical applications.
As a basis for understanding this concept:
a. Students know how to predict the voltage or current in simple
direct current (DC)
electric circuits constructed from batteries, wires, resistors,
and capacitors.
b. Students know how to solve problems involving Ohm’s
law.
c. Students know any resistive element in a DC circuit
dissipates energy, which heats
the resistor. Students can calculate the power (rate of energy
dissipation) in any
resistive circuit element by using the formula Power = IR
(potential difference) ×
I (current) = I2R.
d. Students know the properties of transistors and the role of
transistors in electric
circuits.
e. Students know charged particles are sources of electric
fields and are subject to the
forces of the electric fields from other charges.
f. Students know magnetic materials and electric currents
(moving electric charges)
are sources of magnetic fields and are subject to forces arising
from the magnetic
fields of other sources.
g. Students know how to determine the direction of a magnetic
field produced by a
current flowing in a straight wire or in a coil.
h. Students know changing magnetic fields produce electric
fields, thereby inducing
currents in nearby conductors.
i. Students know plasmas, the fourth state of matter, contain
ions or free electrons or
both and conduct electricity.
j.* Students know electric and magnetic fields contain energy
and act as vector force
fields.
k.* Students know the force on a charged particle in an electric
field is qE, where E is
the electric field at the position of the particle and q is the
charge of the particle.
l.* Students know how to calculate the electric field resulting
from a point charge.
m.* Students know static electric fields have as their source
some arrangement of
electric charges.
n.* Students know the magnitude of the force on a moving
particle (with charge q) in
a magnetic field is qvB sin(a), where a is the angle between v
and B (v and B are
the magnitudes of vectors v and B, respectively), and students
use the right-hand
rule to find the direction of this force.
o.* Students know how to apply the concepts of electrical and
gravitational potential
energy to solve problems involving conservation of energy.
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These are the California standards taken directly from their
PDF. I've only modified them slightly for formatting, but other
than that, no changes have been made. If there are any questions
on ANY of the subject matter, you can ask in this thread or in a
message. Also consult your local physics teacher, since they'll
probably do a much better job at explaining things that I will.
FORMULAS
Subject to change
Force=mass*acceleration | (Newton's 2nd Law)
acceleration=velocity*2/radius | (Centripetal Acceleration *WE
PROBABLY WON'T COVER THIS*)
Energy=(1/2)mass*velocity*2 | (Calculating Kinetic Energy)
<change in potential energy> = mass*gravity*height |
(Calculating Change of Potential Energy)
Calculating Electricity
HTML http://www.ict4us.com/r.kuijt/images/en_ohm.jpg
Speed(C or v)=Wavelength(λ(lambda))*Frequency(f) |
(Calculating Wavelength, Frequency, and Speed)
#Post#: 368--------------------------------------------------
Re: Physics
DIR By: Red
Date: April 25, 2013, 11:12 am
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Motion and Forces
<reserved>
#Post#: 369--------------------------------------------------
Re: Physics
DIR By: Red
Date: April 25, 2013, 11:13 am
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Conservation of Energy and Momentum
<reserved>
#Post#: 370--------------------------------------------------
Re: Physics
DIR By: Red
Date: April 25, 2013, 11:14 am
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Heat and Thermodynamics
<reserved>
#Post#: 371--------------------------------------------------
Re: Physics
DIR By: Red
Date: April 25, 2013, 11:15 am
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Waves
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What is a wave?
Waves, at their most basic, are oscillations or vibrations of
energy with or without a medium (matter to be channeled
through).
All waves have four fundamental details which describe them.
These are Frequency, Wavelength, Speed, and Amplitude.
Frequency - How often a wave oscillates, or completes one cycle
of going up and down, or high and low. These are measured in Hz,
or oscillations per second. 1 GHz (Gigahertz) is 1,000,000,000
oscillations per second, for example.
Wavelength - The literal length of one oscillation. These are
measured in meters and can be extremely small or gigantic (over
several kilometers).
Speed - How quickly the wave's energy travels across space.
These are measured in meters per second I believe.
Amplitude - The strength or potency of a wave. Amplitude is a
measure of how much energy a wave transmits, which is measured
in joules. We won't worry about this too much. A sound frequency
sent through an amplifier will produce a louder sound than
before, giving the wave much more volume than before.
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Types of waves
There are two main types of waves that we will cover in this
guide, that those are Mechanical and Electromagnetic.
Mechanical waves are probably the most straightforward to
understand. If you take a rope, lay it straight across the
ground and then whip your arm up and down while holding an end
of it, you can see long arcs of energy transfer across the rope.
You can also see this if you throw a stone into a body of water.
The ripples on the surface are also mechanical waves.
Additionally, all sound waves are mechanical. Sound waves are
transferred through the air by changes is air pressure. When
sound is produced by a speaker, the speaker vibrates and hits
the air particles around it, giving them kinetic energy and
creating a change in air pressure right on its surface. This
increased pressure naturally wants to transfer to the areas of
low pressure surrounding it, and so it does, and the compressed
particles of air hit other particles of air which hit other
particles, transferring energy from one to the next. This
process repeats until the particles run out of the supplied
kinetic energy and go back to what they were doing. When air
particles hit your eardrum, they cause it to vibrate, and the
mechanics within your ear allow you to effectively hear things.
The other type of wave is the Electromagnetic wave. The
difference between electromagnetic and mechanical waves is that
mechanical waves need some sort of matter to be transferred
through. The energy in mechanical waves is only good when
there's something there to manipulate. Electromagnetic waves
don't need particles to transfer through, and thus, can travel
through space and other vacuums, and also walls.
(The following delves more into chemistry) Quantum theory, or
the study of the basics of matter, suggests that all particles
have some sort of frequency around them (this also relates to
String Theory -
HTML http://en.wikipedia.org/wiki/String_theory).<br
/>Most of the frequencies of particles would be considered
electromagnetic waves, also know as radiation. This means that
everything gives off some sort of radiation, as long as it's
matter. The more unstable the atom, the more radiation it gives
off in several forms, and one of these forms is known as Gamma
radiation (Y). Gamma radiation can be harmful in large amounts,
since it is one of the electromagnetic waves with the smallest
wavelength, and can effect how atoms behave.
Light and radio waves are also electromagnetic waves.
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[center]
HTML http://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/EM_spectrum.svg/787px-EM_spectrum.svg.png[/center]
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As far as how waves travel and disperse energy, they do so in
two forms. These identify a wave as Transverse or Longitudinal.
Wikipedia does an excellent job of explaining them.
Transverse:
HTML http://en.wikipedia.org/wiki/Transverse_wave
Longitudinal:
HTML http://en.wikipedia.org/wiki/Longitudinal_wave
<will be continued>
#Post#: 372--------------------------------------------------
Re: Physics
DIR By: Red
Date: April 25, 2013, 11:16 am
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Electric and Magnetic Phenomena
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