{VERSION 4 0 "IBM INTEL NT" "4.0" } {USTYLETAB {CSTYLE "Maple Input" -1 0 "Courier" 0 1 255 0 0 1 0 1 0 0 1 0 0 0 0 1 }{CSTYLE "" -1 23 "Courier" 1 10 0 0 0 0 0 0 0 0 0 0 3 0 0 1 }{PSTYLE "Normal" -1 0 1 {CSTYLE "" -1 -1 "" 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 }0 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 }} {SECT 0 {EXCHG {PARA 0 "" 0 "" {TEXT 23 64 "Math 2250 Maple Lab 2b, N ovember 2005. Mechanical Oscillations." }}{PARA 0 "" 0 "" {TEXT 23 0 " " }}{PARA 0 "" 0 "" {TEXT 23 72 "NAME _______________________ CLASSTI ME ____ VERSION A-E, F-K, L-R, S-Z" }}{PARA 0 "" 0 "" {TEXT 23 0 "" } }{PARA 0 "" 0 "" {TEXT 23 66 "Circle the version - see problem 2.4. Th ere are three (3) problems" }}{PARA 0 "" 0 "" {TEXT 23 58 "in this pro ject. Please answer the questions A, B, C , ..." }}{PARA 0 "" 0 "" {TEXT 23 52 "associated with each problem. The original worksheet" }} {PARA 0 "" 0 "" {TEXT 23 65 "\"2250mapleL2b-F2005.mws\" is a template \+ for the solution; you must" }}{PARA 0 "" 0 "" {TEXT 23 65 "fill in the code and all comments. Sample code can be copied with" }}{PARA 0 "" 0 "" {TEXT 23 61 "the mouse. Use pencil freely to annotate the workshe et and to" }}{PARA 0 "" 0 "" {TEXT 23 29 "clarify the code and figures ." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 59 "The \+ problem headers for the Fall 2005 version of Mechanical" }}{PARA 0 "" 0 "" {TEXT 23 26 "Oscillations maple lab 2b." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 47 " __________2.4. UNDER-DAMPED FR EE OSCILLATIONS." }}{PARA 0 "" 0 "" {TEXT 23 45 " __________2.5. UNDAM PED FORCED OSCILLATIONS." }}{PARA 0 "" 0 "" {TEXT 23 36 " __________2. 6. PRACTICAL RESONANCE." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 45 "2.4. PROBLEM (UNDER-DAMPED FREE OSCILLATIONS)" }} {PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 67 "FREE OSCI LLATIONS. Consider the problem of free linear oscillations" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 32 " m x'' \+ + c x' + k x=0," }}{PARA 0 "" 0 "" {TEXT 23 28 " x(0)=0, x' (0)=1." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 66 "Here, m, c and k are non-negative constants. The under-damped case" } }{PARA 0 "" 0 "" {TEXT 23 63 "is studied here, c^2 < 4km, as on page 3 27 in E&P. Depending on" }}{PARA 0 "" 0 "" {TEXT 23 43 "the first lett er of your last name, assume:" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }} {PARA 0 "" 0 "" {TEXT -1 115 " Version A-E: m=1, c=5 Versi on F-K: m=2, c=3\n Version L-R: m=4, c=6 Version S-Z: m=4, c=5\n\n" }{TEXT 23 68 " A. Display a Hooke's constant k > 0 so tha t the solution x(t) is" }}{PARA 0 "" 0 "" {TEXT 23 63 " under-da mped. Check that x(t)=0 for infinitely many t>0." }}{PARA 0 "" 0 "" {TEXT 23 64 " Display the exact solution x(t) obtained by maple \+ methods" }}{PARA 0 "" 0 "" {TEXT 23 31 " as in the example below ." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 70 " \+ B. Plot the exact symbolic solution x(t) on a suitable t-interval." }} {PARA 0 "" 0 "" {TEXT 23 62 " Check the graphic against Figure 5 .4.9 page 328 of E&P." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 70 " C. Estimate from the graph the decimal value of th e pseudo-period." }}{PARA 0 "" 0 "" {TEXT 23 70 " Display the gr aphical estimate and also the exact pseudo-period" }}{PARA 0 "" 0 "" {TEXT 23 72 " 2Pi/w, where w is the natural frequency of the tri gonometric term" }}{PARA 0 "" 0 "" {TEXT 23 48 " in the solution x(t) found in item 2.4.A." }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}} {EXCHG {PARA 0 "" 0 "" {TEXT 23 93 "EXAMPLE(Wrong parameters! Change i t!) # Use semicolons to see what you have done." }}{PARA 0 "" 0 "" {TEXT 23 84 "de:=3*diff(x(t),t,t)+1.5*diff(x(t),t)+4*x(t)=0: # Define the differential equation" }}{PARA 0 "" 0 "" {TEXT 23 86 " solve(3*r^2+1.5*r+4=0,r); # Solve the characte ristic equation." }}{PARA 0 "" 0 "" {TEXT 23 81 "ic:=x(0)=0,D(x)(0)= 1 : # Define the initial conditions" }}{PARA 0 "" 0 "" {TEXT 23 79 "p:=dsolve(\{de,ic\},x(t),method=laplace): \+ # Symbolically solve for x(t)" }}{PARA 0 "" 0 "" {TEXT 23 79 "X:= unapply(rhs(p),t): # Capture the dsolve sy mbolic" }}{PARA 0 "" 0 "" {TEXT 23 77 " \+ # answer as a function X(t)" }}{PARA 0 "" 0 "" {TEXT 23 69 "plot(X(t),t=0..5); # Plot \+ the solution" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{EXCHG {PARA 0 "" 0 "" {TEXT 23 66 "Maple tip: Click with the mouse on the graphic to print the cursor" }}{PARA 0 "" 0 "" {TEXT 23 65 "location (left upper corner of the maple window). The coordinates" }}{PARA 0 "" 0 "" {TEXT 23 66 "printed are of the form (x,y). From this coordinate infor mation, a" }}{PARA 0 "" 0 "" {TEXT 23 40 "simple subtraction estimates the period." }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "#2.4-A Define k, then solve." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 65 "# under-damped means mr^2+cr+k=0 has two conjugate co mplex roots." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 12 "#2.4-B Plot ." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 34 "#2.4-C Pseudo-period c alculations." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{PARA 0 "" 0 "" {TEXT 23 44 "2.5. PROBLEM (UNDAMPED FORCED OSCILLATIONS )" } }{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 71 "FORCED L INEAR OSCILLATIONS. Consider the undamped (c=0) forced problem" }} {PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 30 " mx' ' + k x = 5 cos(wt)," }}{PARA 0 "" 0 "" {TEXT 23 23 " x(0)=0, x '(0)=0," }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 67 "where m, k and w are non-negative constants. Depending on the firs t" }}{PARA 0 "" 0 "" {TEXT 23 33 "letter of your last name, assume:" } }{PARA 0 "" 0 "" {TEXT -1 0 "" }}{PARA 0 "" 0 "" {TEXT 23 118 " Versio n A-E: m=1, k=3.7 Version F-K: m=2, k=2.7\n Version L-R: m=3 , k=4.8 Version S-Z: m=4, k=4.6" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 72 " A. Choose the forcing angu lar frequency w to be 3 times larger than" }}{PARA 0 "" 0 "" {TEXT 23 72 " the natural angular frequency w0, w0^2=k/m. Solve for x(t) using" }}{PARA 0 "" 0 "" {TEXT 23 72 " dsolve(). Plot the solu tion x(t) on a suitable interval in order" }}{PARA 0 "" 0 "" {TEXT 23 68 " to show the global behavior of the solution x(t). See Figu re" }}{PARA 0 "" 0 "" {TEXT 23 24 " 5.6.2, page 350." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 67 " B. The solu tion x(t) is the sum of two functions, one of period" }}{PARA 0 "" 0 " " {TEXT 23 70 " 2Pi/w and the other of period 2Pi/w0. Display th e exact period," }}{PARA 0 "" 0 "" {TEXT 23 67 " as calculated f rom the solution formula for x(t) -- see page" }}{PARA 0 "" 0 "" {TEXT 23 23 " 350 for details." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 62 " C. Suggest a value for the forcing \+ frequency w so that the" }}{PARA 0 "" 0 "" {TEXT 23 67 " oscilla tions exhibit resonance. Show resonant behavior on a" }}{PARA 0 "" 0 "" {TEXT 23 51 " graph. Check against Figure 5.6.4, page 352." } }{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{EXCHG {PARA 0 "> " 0 " " {MPLTEXT 1 0 6 "#2.5-A" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 6 " #2.5-B" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 6 "#2.5-C" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{PARA 0 "" 0 "" {TEXT 23 34 "2. 6. PROBLEM (PRACTICAL RESONANCE)" }}{PARA 0 "" 0 "" {TEXT 23 37 " Co nsider the damped forced problem" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }} {PARA 0 "" 0 "" {TEXT 23 37 " mx'' + c x' + k x = 5 cos(w t)," }} {PARA 0 "" 0 "" {TEXT 23 23 " x(0)=0, x'(0)=0." }}{PARA 0 "" 0 " " {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 56 "Depending on the first \+ letter of your last name, assume:" }}{PARA 0 "" 0 "" {TEXT -1 0 "" }} {PARA 0 "" 0 "" {TEXT 23 111 " Version A-E: m=1, k=35 Version F-K: m=2, k=38\n Version L-R: m=3, k=48 Version S-Z: m=4, k= 58" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 70 " \+ A. Consider the damping constants c=2, c=1 and c=1/2. Compute the" } }{PARA 0 "" 0 "" {TEXT 23 68 " amplitude function C(w) [page 357 ] for these three equations," }}{PARA 0 "" 0 "" {TEXT 23 71 " th en plot for w=0 to w=20 the three amplitude graphs on a single" }} {PARA 0 "" 0 "" {TEXT 23 72 " set of axes. Compare against Figur e 5.6.9 page 357 of E&P (it has" }}{PARA 0 "" 0 "" {TEXT 23 38 " \+ one curve, yours has 3 curves)." }}{PARA 0 "" 0 "" {TEXT 23 0 "" }} {PARA 0 "" 0 "" {TEXT 23 67 " B. For each case c=2, c=1, c=1/2, pri nt the values w*, C* where" }}{PARA 0 "" 0 "" {TEXT 23 70 " C*=C (w*)=max \{C(w) : 0 <= w <= 20\}. The three data pairs should" }} {PARA 0 "" 0 "" {TEXT 23 70 " show that C* becomes larger as c t ends to zero. SAVE YOUR MAPLE" }}{PARA 0 "" 0 "" {TEXT 23 22 " F ILE FREQUENTLY" }}{PARA 0 "" 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 69 " Maple Hint: Use Maple's mouse interface on the graphi c of Part C." }}{PARA 0 "" 0 "" {TEXT 23 69 " Specifically, click o n a possible maximum (horizontal tangent) in" }}{PARA 0 "" 0 "" {TEXT 23 66 " the graph to display the values w*, C* on the screen. Copy \+ the" }}{PARA 0 "" 0 "" {TEXT 23 20 " values on paper." }}{PARA 0 " " 0 "" {TEXT 23 0 "" }}{PARA 0 "" 0 "" {TEXT 23 30 "EXAMPLE(Beware! Wr ong values!)" }}{PARA 0 "" 0 "" {TEXT 23 35 "F:=15: m:=1: k:=25: c:='c ': w:='w':" }}{PARA 0 "" 0 "" {TEXT 23 38 "C:=(w,c)->F/sqrt((k-m*w*w)^ 2+(c*w)^2):" }}{PARA 0 "" 0 "" {TEXT 23 49 "plot(\{C(w,4),C(w,3),C(w,2 )\},w=0..15,color=black);" }}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 " " }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 51 "#2.6-A Plot C(w), three graphics on one set of axes" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 42 "#2.6-B Table of six data values for w*, C*" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}}{MARK "0 0 0" 54 }{VIEWOPTS 1 1 0 1 1 1803 1 1 1 1 }{PAGENUMBERS 0 1 2 33 1 1 }