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An Abridged Highschool Physics course....

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votefornimitz

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<p>In the "Welcome to Physics" thread on this forum, dryson asked if anyone would be willing to start a thread covering basic physics principles and there application. Granted, I'm not a physicist (not yet at least, planning on an Astronomy or Astrophysics major with an Atmospheric Sciences minor), I am in a rather high level physics course in high school.</p><p>Its a two year course, but being that I am only in the first year, I'll cover one topic each week so I can give my instructor time to get the topics in before I get to them on this forum....</p><p>This would also be the place where you ask questions and what not, and I will answer them to the bet of my ability, and if I or others here cannot answer them, I will bring them to my physics instructor. &nbsp;</p><p>Topics cover will be...</p><ul><li>Kinematics</li><li>Two Dimensional Motion and Vectors</li><li>Forces, Motion, Application of Newton's 2nd Law</li><li>Energy, Work, and Energy Relationships</li><li>Collisions and One Dimensional Momentum</li><li>Centripetal Forces, Universal Gravitation, and Kepler's Laws</li></ul><p>This is all I have covered so far in class, and thus all I am qualified to share knowledge the knowledge of. </p><p>I'm assuming that anyone participating in this thread is familiar with the scientific method, precision and accuracy, propagation of error, and the metric system. If not, ask, but unless asked, I do not plan on covering these subjects....</p><p>I'll post the Kinematics lesson later today for discussion.&nbsp;</p> <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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votefornimitz

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<p>Physics is a science, and like all sciences, it requires the use of large, complicated sounding words to illustrate rather simple things. This allows physicists to feel more like gurus and less like nerds. </p><p>Essentially, (linear) Kinematics is motion. Motion in a straight line, with <span style="font-weight:bold">constant acceleration</span>. Velocity can change, but acceleration must be maintain throughout the problem in order for kinematics equations to be used to solve it. There are 4 equations it would be best to commit to memory if you want to be good at kinematics (which are luckily almost identical for rotational and linear kinematics, the former being covered quite a bit down the road.) but before we get into them, we need to know what you need to know, aka, what the variables indicate.</p>&nbsp;<span style="font-weight:bold">u: The starting velocity, the speed essentially at which the object you are looking at starts in the problem. Measured in meters per second (m/s)</span><br /><span style="font-weight:bold">&nbsp;</span><br /><span style="font-weight:bold">v: The final velocity, the final velocity is the speed after whatever is going to happen to the object has happened, bit it slowing down or speeding up for a set amount of time. Measured in meters per second (m/s)</span><br />&nbsp;&nbsp;<p><span style="font-weight:bold">s: The distance covered in the problem. How far it goes over a period of time or acceleration. Measured in Meters (m)</span></p><p>&nbsp;</p><p style="font-weight:bold">a: Acceleration, the speed up or slowing down of an object. Positive for speeding up, negative for slowing down. Measured in meters per second squared (m/s^2).</p><p style="font-weight:bold">&nbsp;</p><p style="font-weight:bold">t: The time it takes for the velocity to change from u to v or the time it takes for distance s to be covered. Measured in seconds (s)</p><p style="font-weight:bold">&nbsp;</p><p>The four base equations we can manipulate are...</p><p style="font-weight:bold">s=1/2(u+v)t</p><p style="font-weight:bold">v=u+at</p><p style="font-weight:bold">s=ut+1/2a(t^2)</p><p style="font-weight:bold">v^2=(u^2)+2as</p><p>&nbsp;</p><p>So, if you drop an object off a 50 meter build and want to know what speed it will be going the instant before it hits the ground, you'd find out what values you have and what equation to use.</p><p>You have s, it being 50 meters</p><p>You have u, being 0 m/s</p><p>You have a, as the value of acceleration due to gravity on Earth is 9.8 m/s^2 .</p><p>You want v.</p><p>Looking at the above equations, you would input all of those values into equation four, to find v.</p><p>&nbsp;<em>v^2=u^2+2as</em></p><p><em>v^2=0^2+2(9.8)(50)</em></p><p><em>v^2=245</em></p><p><em>v= ~15.65</em></p><p>Because v is a velocity variable, you know the units will be in meters per second....&nbsp;</p><p>&nbsp;</p><p>****Note that all of linear kinematics and most of physics at the high school level ignores air resistance*****&nbsp;</p> <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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majornature

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In the "Welcome to Physics" thread on this forum, dryson asked if anyone would be willing to start a thread covering basic physics principles and there application. Granted, I'm not a physicist (not yet at least, planning on an Astronomy or Astrophysics major with an Atmospheric Sciences minor), I am in a rather high level physics course in high school.Its a two year course, but being that I am only in the first year, I'll cover one topic each week so I can give my instructor time to get the topics in before I get to them on this forum....This would also be the place where you ask questions and what not, and I will answer them to the bet of my ability, and if I or others here cannot answer them, I will bring them to my physics instructor. &nbsp;Topics cover will be...KinematicsTwo Dimensional Motion and VectorsForces, Motion, Application of Newton's 2nd LawEnergy, Work, and Energy RelationshipsCollisions and One Dimensional MomentumCentripetal Forces, Universal Gravitation, and Kepler's LawsThis is all I have covered so far in class, and thus all I am qualified to share knowledge the knowledge of. I'm assuming that anyone participating in this thread is familiar with the scientific method, precision and accuracy, propagation of error, and the metric system. If not, ask, but unless asked, I do not plan on covering these subjects....I'll post the Kinematics lesson later today for discussion.&nbsp; <br />Posted by votefornimitz</DIV></p><p>&nbsp;Man I missed those days...By the way, I'm a chemistry/physics!&nbsp; And it all started in highschool.&nbsp; I couldn't choose between the two so I took both.&nbsp; Mainly i stuck with chemistry so my degree will be in that field.&nbsp; I have like a semester left before obtain my degree and then to finish conquering physics.</p><p>&nbsp;</p><p>Oh, there's a nice oxford's dictornary of Physics!&nbsp; I mean it has everything dealing with physics...it's pretty interesting...<br /></p> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>
 
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votefornimitz

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I can't stand the dimensional analysis aspect of Chemistry, so I am in Physics and Biology this year and next..... <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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Saiph

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<p>Vote, I'll help out by keeping an eye on your posts for mistakes, misconceptions, or miscommunications.&nbsp; Hopefully my B.S. in physics and astronomy will help prevent myself from doing the same :)</p><p>Perhaps I'll start a thread that solves and discusses various physics problems.&nbsp; I could certainly use the practice.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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votefornimitz

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<p>Much Appreciated Saiph....</p><p>How was it like Majoring in Astronomy?</p><p>I've printed off some college astronomy labs, and apart from "error bars", everything on them seemed rather simple, calculating parallax a stellar luminosity, stuff I can do right now... How in depth did it get...</p><p>Basically tell me everything about astronomy in college....</p><p>(I'd love to take stabs at your physics problems threads as well...)&nbsp;</p> <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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Saiph

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<p>Well, to keep it simple (so we don't get to off topic :) ):&nbsp; What you're familiar with is only the 100 and 200 level material most likely.&nbsp; For an idea of what you have to deal with later look at the "Saha-Boltzmann equation" for determining the true composition of a stellar atmosphere.</p><p>Then consider the fact that while an astronomer doesn't need to be awesome at mechanics, quantum theory, electromagnetics, and thermodynamics...his work is spread broadly across all the topics, so you can't just focus on one like, say, a scientist developing new semi-conductors can focus primarily on&nbsp; quantum and solid state.</p><p>&nbsp;_______________________</p><p>As for the physics lecture topics, don't forget to define what these words actually mean.&nbsp; in this case: Velocity, Accelertaion, and distance (i.e. the concept of net displacement)</p> <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Physics is a science, and like all sciences, it requires the use of large, complicated sounding words to illustrate rather simple things. This allows physicists to feel more like gurus and less like nerds. Essentially, (linear) Kinematics is motion. Motion in a straight line, with constant acceleration. Velocity can change, but acceleration must be maintain throughout the problem in order for kinematics equations to be used to solve it. There are 4 equations it would be best to commit to memory if you want to be good at kinematics (which are luckily almost identical for rotational and linear kinematics, the former being covered quite a bit down the road.) but before we get into them, we need to know what you need to know, aka, what the variables indicate.&nbsp;u: The starting velocity, the speed essentially at which the object you are looking at starts in the problem. Measured in meters per second (m/s)&nbsp;v: The final velocity, the final velocity is the speed after whatever is going to happen to the object has happened, bit it slowing down or speeding up for a set amount of time. Measured in meters per second (m/s)&nbsp;&nbsp;s: The distance covered in the problem. How far it goes over a period of time or acceleration. Measured in Meters (m)&nbsp;a: Acceleration, the speed up or slowing down of an object. Positive for speeding up, negative for slowing down. Measured in meters per second squared (m/s^2).&nbsp;t: The time it takes for the velocity to change from u to v or the time it takes for distance s to be covered. Measured in seconds (s)&nbsp;The four base equations we can manipulate are...s=1/2(u+v)tv=u+ats=ut+1/2a(t^2)v^2=(u^2)+2as&nbsp;So, if you drop an object off a 50 meter build and want to know what speed it will be going the instant before it hits the ground, you'd find out what values you have and what equation to use.You have s, it being 50 metersYou have u, being 0 m/sYou have a, as the value of acceleration due to gravity on Earth is 9.8 m/s^2 .You want v.Looking at the above equations, you would input all of those values into equation four, to find v.&nbsp;v^2=u^2+2asv^2=0^2+2(9.8)(50)v^2=245v= ~15.65Because v is a velocity variable, you know the units will be in meters per second....&nbsp;&nbsp;****Note that all of linear kinematics and most of physics at the high school level ignores air resistance*****&nbsp; <br />Posted by votefornimitz</DIV></p><p>The dictionary definition of kinematics (quite accurate) is "&nbsp;a branch of dynamics that deals with aspects of motion apart from considerations of mass and force".&nbsp; Thus linear kinematics is usually construed to mean motion in one dimension, whether at constant velocity or not.&nbsp; The reason that your high school class is focused on the case of constant acceleration is two-fold.&nbsp; First, the case of a falling object, relatively close to the earth is one of constant acceleration.&nbsp; Second, by limiting consideration to constant acceleration, you do not have to use calculus to do the computation.&nbsp; You simply apply the algebraic formulas that you have quoted.</p><p>An unfortunate aspect of that approach is that you are forced to memorize the equations of motion.&nbsp; If the calculus were available, then memorization would not be necessary since the equations of motion can be derived with almost no work from the assumption of linear motion and constant acceleration.&nbsp; In fact the origin of calculus itself is in mechanics and the application is straightforward.</p><p>The development of calculus by Newton goes something like this.&nbsp; Once upon&nbsp;a time in a land far far away there live a man called Tycho Brahe and his faithful servant Johanne Kepler.&nbsp; Tycho was quite wealthy and spent his time accumulating a vast amount of data on the motion of the planets.&nbsp; Kepler was quite clever and analyzed Tycho's data exhaustively.&nbsp; He noticed a regularity in that data, and purely from an empirical point of view developed a set of laws of planetary motion.&nbsp; He noticed that the planets moved in eliptical orbits and did so in such a way as to sweep out equal areas in equal time.&nbsp; Newton, A VERY CLEVER GUY, wondered why such laws might be true on a more fundamental basis.&nbsp; To explain Kepler's laws de developed the theory of universal gravitation, then formulated laws of motion in what we would today call differential equations.&nbsp; In order to both formulate and solve differential equations he was forced to invent calculus.&nbsp; Stir these together and add in the notions of mass force and momentum and, voila, you have Newtonian mechanics -- the centerpiece of classical physics and one of the great successes of the human mind.&nbsp;&nbsp; Newtonian mechanics is really simplicity itself -- all of the theory of classical mechanics is summed up in three very simple laws, and little bit of mathematics.</p><p>Now as to your statement that "Physics ... requires the use of large, complicated sounding words to illustrate rather simple things."&nbsp; Reality is quite the contrary.&nbsp; Physics has always sought to explain the world in the simplest possible terms, and simplicity is the hallmark of the best physical theories.&nbsp; Einstein spent his entire life in the search for simplicity.&nbsp; His special relativity is based on the astounding simple notion that the speed of light in a vacuum is a constant, independent of the reference frame.&nbsp; From that astoundingly simple assumption came one of the great theories of physics, one that upset the Newtonian apple cart.&nbsp; General relativity is, at its base, just as simple -- gravity and acceleration are indistinguishable.</p><p>&nbsp;When you run across so-called scientists who complicate things unnecessarily be skeptical.&nbsp; Complicaton can come from humble beginnings and be appropriate at times, but it can also come from an attempt to obfuscate ignorance.&nbsp; Physics is at the core simple in nature.&nbsp; And to quote James Rutherford "All science is either physics or stamp collecting."&nbsp; Stamp collecting can appear to be quite complicated, but that is due to lack of fundamental principles and deep understanding.</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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