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===Quick links=== ==This wiki== * [[start|Main classwiki page]] * [[CLASS INFORMATION|Class Info]] * {{:Kuzma_Syllab_Spr2014_v4.pdf|Syllabus}} * [[FREQUENTLY ASKED QUESTIONS|FAQ]] * [[CLASS MATERIALS|Class materials]] * [[PHYSICS LABORATORY|Labs]] * [[http://web.pdx.edu/~ralfw/physics/lab/index_files/LabScheduleSpring.pdf|Schedule]] * [[PHYSICS WORKSHOP|Workshop]] * {{:workshops:ph299_syllabus_14sp.pdf|W/S syllabus}} * [[Computational Projects|Projects]] * [[White noise project|White noise]] * [[Rainbow project|Rainbow]] * [[Digital sound project|Digital sound]] * [[Announcements]] ==Earlier material== * [[Chapter 13]] * [[Chapter 14]] * [[Exam 1 review]] * [[Chapter 25]] * [[Chapter 26]] * [[Chapter 27]] * [[Exam 2 review]] * [[Final exam review]] ==Previous wikis== * [[http://web.pdx.edu/~nkuzma/Ph202_2014_wiki|Ph202 - 2014]] ==Other learning tools== * [[http://d2l.pdx.edu|University D2L site]] * [[http://masteringPhysics.com|Text & homework]] \\ <sub><color magenta>PH203KUZMASPRING2014</color></sub> ==Knowledge & computation== * [[http://wolframalpha.com|Wolfram]] $\alpha$ * [[wp>Physics_portal|Wikipedia]] * [[http://physics.nist.gov/cuu/Constants/index.html|Physical constants]] * [[http://physics.info/| The Physics Hypertextbook]] * [[http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html| HyperPhysics]] ==Add more by editing:== * [[sidebar|This sidebar]] * [[Tasks to do]] ==Help for editors== * [[doku>wiki:syntax|Help on wiki codes]] * [[http://en.wikibooks.org/wiki/LaTeX/Mathematics|Help on wiki math]] * [[Tips on editing]] =="Sandboxes" for practice== * [[Draft page|Practice here]] * [[Draft page 2|Or here if locked-out]]

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=====Practice/work here if other pages are temporarily locked by other editors===== ---- ===Problem 1.3.13.13=== Two pendulums (or, //pendula//) are made of identical 1 kg masses suspended on two weightless strings, 40.0 and 40.5 cm in length. If these pendulums are deflected from vertical by 5 cm and released at the same time, how long will it take for them to get completely "out of step" with each other? Steps: - Convert **relevant** quantities to SI units: * $l_1$ = 40.0 cm = 0.400 m * $l_2$ = 40.5 cm = 0.405 m * masses and (small) deflections are irrelevant for finding periods and timing of oscillations - Find each period: * $T_1=2\pi\sqrt{\frac{l_1}{g}}$ $\approx 6.283\sqrt{\frac{0.400\,{\text m}}{9.8\,\frac{\text m}{ {\text s}^2}}}=1.269\,$s * $T_2=2\pi\sqrt{\frac{l_2}{g}}$ $\approx 6.283\sqrt{\frac{0.405\,{\text m}}{9.8\,\frac{\text m}{ {\text s}^2}}}=1.277\,$s - By the time $t$ the two pendulums are "out of step", one would have completed an extra 1/2 periods compared to the other: * $t = \left(n+\frac{1}{2}\right)T_1=nT_2$ {{ :figs:lec01fg4.png?nolink|}} - Use this relationship to solve for $n$, then find $t$: * first, open the parentheses: $t= nT_1+\frac{1}{2}T_1=nT_2$ * then, isolate $n$ by combining terms: $\frac{1}{2}T_1=nT_2-nT_1=n\,(T_2-T_1)$ * lastly, $n=\frac{T_1}{2(T_2-T_1)}$ $=\frac{1.269\,{\text s}}{2\,\cdot\,8\times 10^{-3}\,{\text s}}$ $=79$ * $t=nT_2$ $=79\cdot1.277\,{\text s}\approx 100\,$s - Make sense of the answer: * This is much longer than the periods of oscillations, but short enough to observe the effect before the oscillations die down due to friction

draft_page_2.1396332882.txt.gz · Last modified: 2014/04/01 06:14 by wikimanager