{ "information": { "Title": "ejss_model_dopplerxywee01 Doppler Effect Sound Wave JavaScript Applet", "Author": [ "Fu-Kwun Hwang and remixed by lookang (weelookang@gmail.com)", "lookang" ], "AuthorLogo": [ "./01authorfu-kwun.hwang.png", "./01authorlookang50x50.png" ], "Password": "", "Keywords": "", "Abstract": "http://weelookang.blogspot.sg/2016/03/doppler-effect-sound-wave-javascript.html", "Copyright": "Creative Commons Attribution", "Level": "", "Language": "", "Logo": [ "./doppler/Screen Shot 2017-05-25 at 11.17.57 AM (2).png" ], "RunAlways": "true", "ModelTab": "", "ModelTabTitle": "", "ModelName": "", "FixedNavigationBar": "false", "CSSFile": "", "DetectedFiles": [ "./01authorfu-kwun.hwang.png", "./01authorlookang50x50.png", "./doppler/Screen Shot 2017-05-25 at 11.17.57 AM (2).png" ], "AuxiliaryFiles": [ "./doppler/" ], "HTMLHead": "\n\n", "SaveInXMLFormat": "false", "IncludeSource": "true", "IncludeLibrary": "true", "UglifyJS": "false", "PreviewFullModel": "false", "UseInterpreter": "true", "UseDeltaForODE": "false" }, "description": { "pages": [ { "Name": "Intro Page", "Active": "true", "Internal": "true", "Type": "DESCRIPTION_EDITOR", "Locale": "_default_", "Title": "Intro Page", "External": "false", "Code": "\n\n\n

Designed by Fu-Kwun Hwang http://www.phy.ntnu.edu.tw/ntnujava/ remixed by lookang Reference taken from Juan M. Aguirregabiria's http://www.compadre.org/osp/items/detail.cfm?ID=7902 and Andrew Duffy's http://www.compadre.org/osp/items/detail.cfm?ID=9982 which made the remixing of this simulation a lot easier :) lookang thanks to the all of them great physics teachers. For more info: http://weelookang.blogspot.sg/2011/09/ejs-open-source-1-dimension-doppler.html

The Doppler effect

The Doppler effect describes the shift in frequency of a wave that is produced by the motion of either the wave source or the observer of the wave (or both).

A sound source is moving with velocity v along the horizontal axis. Every period T a wave front leaves the source and travels with velocity c with respect to a medium (say air), assuming no air motion. A detector is located at position (x, y) and may move with velocity (dx/dt, dy/dt). To promote ease of learning, only the x direction is enabled, thus, making exploration confined to 1 Dimension.

In the graphics window below the animation a vertical red (green) bar is displayed each time a wave front leaves the source (reaches the detector).

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document.webkitExitFullscreen();\n }\n }\n}" }, { "Name": "playpause", "Active": "false", "Internal": "false", "Type": "LIBRARY_EDITOR", "Comment": "", "Code": "function playpause () {\n if(label==l_play){\n label=l_pause;\n _play();\n }else{\n label=l_play;\n _pause();\n }\n}" }, { "Name": "distance", "Active": "true", "Internal": "false", "Type": "LIBRARY_EDITOR", "Comment": "", "Code": "function distance ( dx, dy) {\n return Math.sqrt(dx*dx+dy*dy);\n}" } ] }, "elements": { "list": [] } }, "view": { "Tree": [ { "Name": "panel", "Type": "Panel", "Expanded": "true", "Properties": [ { "name": "Width", "value": "Width" } ], "Children": [ { "Name": "controlpanel", "Type": "Panel", "Expanded": "false", "Properties": [ { "name": "Display", "value": "!print?\"inline-flex\":\"none\"" }, { "name": "Font", "value": "font" } ], "Children": [ { "Name": "scenariobox", "Type": "ComboBox", "Properties": [ { "name": "Options", "value": "[\"Stationary source\",\"\",\"Doppler effect\",\"vs = 0.3c\",\"vs = 0.5c\",\"vs = 0.7c\",\"Break sound barrier vs=c\",\"Supersonic vs=1.4c\",\"Moving observer\",\"vo = 0.3c\",\"vo = 0.5c\",\"vo = 0.7c\",\"vo = c\",\"vo = 1.4c\",\"Scenario 2\",\"Scenario 3\",\"Scenario 4\",\"Scenario 5\",\"\",\"print\"]" }, { "name": "OnChange", "value": "var opts1 = _view.scenariobox.getProperty(\"SelectedOptions\"); // array of options\nvar option1 = (opts1.length > 0)? opts1[0]:\"\"; // selected option \nif ( option1==\"Stationary source\"){\nvx = 0;\nx = 0;\nxe = 6*v0;\nvxobserver = 0; //put far\n_initialize();\n}\n//\"vs = 0.1c\",\"vs = 0.5c\",\"vs = 0.7c\",\"vs = 0.76c\"\n//print\nelse if (option1 == \"print\"){\n print = true;\n }\n//print\nelse if ( option1==\"vs = 0.3c\"){\nvx = v0*0.3;\nx = -vx*20;\nxe = 0;\nvxobserver = 0;\n_initialize();\n}\nelse if ( option1==\"vs = 0.5c\"){\nvx = v0*0.5;\nx = -vx*10;\nxe = 0;\nvxobserver = 0;\n_initialize();\n}\nelse if ( option1==\"vs = 0.7c\"){\nvx = v0*0.7;\nx = -1848;\nxe = 0;\nvxobserver = 0;\n_initialize();\n}\nelse if ( option1==\"Break sound barrier vs=c\"){\nvx = v0;\nx = -vx*6;\nxe = 0;\nvxobserver = 0;\n_initialize();\n}\n//\"Supersonic\"\nelse if ( option1==\"Supersonic vs=1.4c\"){\nvx = v0*1.4;\nx = -vx*4;\nxe = 0;\nvxobserver = 0;\n_initialize();\n}\nelse if ( option1==\"vo = 0.3c\"){\nvx = 0;\nx = -vx*20;\n\nvxobserver = v0*0.3;\nxe = -vxobserver*20;\n_initialize();\n}\nelse if ( option1==\"vo = 0.5c\"){\nvx = 0;\nx = -vx*20;\n\nvxobserver = v0*0.5;\nxe = -vxobserver*10;\n_initialize();\n}\nelse if ( option1==\"vo = 0.7c\"){\nvx = 0;\nx = -vx*20;\n\nvxobserver = v0*0.7;\nxe = -1848;\n_initialize();\n}\nelse if ( option1==\"vo = c\"){\nvx = 0;\nx = -vx*20;\n\nvxobserver = v0*0.9999; // debug if need smaller a bit\nxe = -vxobserver*6;\n_initialize();\n}\nelse if ( option1==\"vo = 1.4c\"){\nvx = 0;\nx = -0.001;\n\nvxobserver = v0*1.4;\nxe = -vxobserver*4+0.001;\n_initialize();\n}\n\nelse if ( option1==\"Scenario 1\"){\nvx = 250;\nx = -vx*6;\nxe = 0;\nvxobserver = 0;\n_initialize()\n}\nelse if ( option1==\"Scenario 2\"){\nx = xmin/2;\nxe = 0;\nvx = 0;\nvxobserver = 150;\n_initialize()\n}\nelse if ( option1==\"Scenario 3\"){\nx = xmin/2;\nxe = 0;\nvx = 250;\nvxobserver = 100;\n_initialize()\n}\nelse if ( option1==\"Scenario 4\"){\nx = xmin/2;\nxe = xmax/2;\nvx = 250;\nvxobserver = -150;\n_initialize()\n}\nelse if ( option1==\"Scenario 5\"){\nx = xmin;\nxe = 0;\nvx = 450;\nvxobserver = 0;\n_initialize()\n}" }, { "name": "Font", "value": "font" } ] }, { "Name": "controlcomboBox", "Type": "ComboBox", "Properties": [ { "name": "Options", "value": "[\"Show World\",\"Hide World\",\"\",\"Show Graph\",\"Hide Graph\",\"\",\"Sound On\",\"Sound Off\",\"\",\"print\"]" }, { "name": "Tooltip", "value": "\"World View\"" }, { "name": "OnChange", "value": "var opts = _view.controlcomboBox.getProperty(\"SelectedOptions\"); // array of options\nvar option = (opts.length > 0)? opts[0]:\"\"; // selected option \n\nif ( option==\"Show World\"){\nworld=true;\nWidth1 = 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"name": "Disabled", "value": "disabledworld" }, { "name": "OnCheckOn", "value": "world=true;\nWidth1 = \"50%\";\nWidth2 = \"50%\";\ndisabled=false;\n" } ] }, { "Name": "xvst", "Type": "CheckBox", "Properties": [ { "name": "Checked", "value": "graph" }, { "name": "OnCheckOff", "value": "graph=false;\nWidth1 = \"100%\";\nWidth2 = \"0%\";\ndisabledworld=true;" }, { "name": "Background", "value": "\"Blue\"" }, { "name": "Foreground", "value": "\"White\"" }, { "name": "Text", "value": "\"emit/detect\"" }, { "name": "Disabled", "value": "disabled" }, { "name": "OnCheckOn", "value": "graph=true;\nWidth1 = \"50%\";\nWidth2 = \"50%\";\ndisabledworld=false;" } ] }, { "Name": "sound", "Type": "CheckBox", "Properties": [ { "name": "Checked", "value": "sound" }, { "name": "Text", "value": "\"sound\"" }, { "name": "ImageOnUrl", "value": "\"./doppler/SoundOn.gif\"" }, { "name": "ImageOffUrl", "value": "\"./doppler/SoundOff.gif\"" } ] }, { "Name": "playPauseButton2", "Type": "TwoStateButton", 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"Slider", "Properties": [ { "name": "Maximum", "value": "2" }, { "name": "Minimum", "value": "1" }, { "name": "Background", "value": "\"Red\"" }, { "name": "Tooltip", "value": "\"Period\"" }, { "name": "Value", "value": "T" }, { "name": "OnChange", "value": "%_initialize%" } ] } ] }, { "Name": "panel_3", "Type": "Panel", "Expanded": "true", "Properties": [ { "name": "Background", "value": "\"Magenta\"" } ], "Children": [ { "Name": "label322", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"Source velocity\"" }, { "name": "Text", "value": "\" v source=\"" } ] }, { "Name": "field222", "Type": "ParsedField", "Properties": [ { "name": "Format", "value": "\"000\"" }, { "name": "Value", "value": "vx" }, { "name": "OnChange", "value": "%_initialize%" }, { "name": "Width", "value": "\"6vw\"" }, { "name": "Font", "value": "font" } ] }, { "Name": "label2222", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"metre per second\"" }, { "name": "Text", "value": "\" m/s \"" }, { "name": "Width", "value": "(_isEPub)?\"0\":\"\"" } ] }, { "Name": "slider222", "Type": "Slider", "Properties": [ { "name": "Maximum", "value": "c" }, { "name": "Minimum", "value": "-c" }, { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"Source velocity\"" }, { "name": "Value", "value": "vx" }, { "name": "OnChange", "value": "%_initialize%" } ] } ] }, { "Name": "panel_4", "Type": "Panel", "Expanded": "true", "Properties": [ { "name": "Background", "value": "\"Green\"" } ], "Children": [ { "Name": "label32", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"rgba(0,150,0,1.0)\"" }, { "name": "Tooltip", "value": "\"Sound speed\"" }, { "name": "Foreground", "value": "\"White\"" }, { "name": "Text", "value": "\" v observer = \"" } ] }, { "Name": "field22", "Type": "ParsedField", "Properties": [ { "name": "Format", "value": "\"000\"" }, { "name": "Value", "value": "vxobserver" }, { "name": "OnChange", "value": "%_initialize%" }, { "name": "Width", "value": "\"5vw\"" }, { "name": "Font", "value": "font" } ] }, { "Name": "label222", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"rgba(0,150,0,1.0)\"" }, { "name": "Tooltip", "value": "\"metre per second\"" }, { "name": "Foreground", "value": "\"White\"" }, { "name": "Text", "value": "\" m/s \"" }, { "name": "Width", "value": "(_isEPub)?\"0\":\"\"" } ] }, { "Name": "slider22", "Type": "Slider", "Properties": [ { "name": "Maximum", "value": "c" }, { "name": "Minimum", "value": "-c" }, { "name": "Background", "value": "\"rgba(0,150,0,1.0)\"" }, { "name": "Tooltip", "value": "\"x component of the detector velocity\"" }, { "name": "Value", "value": "vxobserver" }, { "name": "OnChange", "value": "%_initialize%" }, { "name": "Foreground", "value": "\"White\"" }, { "name": "Width", "value": "(_isEPub)?\"0\":\"\"" } ] } ] }, { "Name": "panel_5", "Type": "Panel", "Expanded": "true", "Properties": [ { "name": "Background", "value": "\"Magenta\"" } ], "Children": [ { "Name": "label3", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"Sound speed\"" }, { "name": "Text", "value": "\" c = \"" } ] }, { "Name": "field2", "Type": "ParsedField", "Properties": [ { "name": "Format", "value": "\"000\"" }, { "name": "Value", "value": "v0" }, { "name": "OnChange", "value": "%_initialize%" }, { "name": "Width", "value": "\"5vw\"" }, { "name": "Font", "value": "font" } ] }, { "Name": "label22", "Type": "Label", "Properties": [ { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"metre per second\"" }, { "name": "Text", "value": "\" m/s \"" }, { "name": "Width", "value": "(_isEPub)?\"0\":\"\"" } ] }, { "Name": "slider2", "Type": "Slider", "Properties": [ { "name": "Maximum", "value": "340" }, { "name": "Minimum", "value": "0" }, { "name": "Background", "value": "\"Magenta\"" }, { "name": "Tooltip", "value": "\"Sound speed\"" }, { "name": "Value", "value": "v0" }, { "name": "OnChange", "value": "%_initialize%" }, { "name": "Width", "value": "(_isEPub)?\"0\":\"\"" } ] } ] } ] }, { "Name": "panel2", "Type": "Panel", "Expanded": "true", "Properties": [ { "name": "Height", "value": "\"80vh\"" }, { "name": "Width", "value": "\"100%\"" } ], "Children": [ { "Name": "plottingPanel", "Type": "PlottingPanel", "Expanded": "false", "Properties": [ { "name": "Gutters", "value": "[0,0,0,0]" }, { "name": "YScalePrecision", "value": "0" }, { "name": "XFixedTick", "value": "0" }, { "name": "OnDoubleClick", "value": "toggleFullScreen();" }, { "name": "YFixedTick", "value": "0" }, { "name": "TRMessage", "value": "print?\"\":\"Doppler Effect Model in 1 Dimension\"" }, { "name": "XTickStep", "value": "vx==0?v0:vx" }, { "name": "YTickStep", "value": "vx==0?v0:vx" }, { "name": "XAutoTicks", "value": "false" }, { "name": "Height", "value": "\"80vh\"" }, { "name": "Width", "value": "Width1" }, { "name": "Background", "value": "\"url(#mygrandient)\"" }, { "name": "Enabled", "value": "true" }, { "name": "SquareAspect", "value": "true" }, { "name": "MaximumY", "value": "ymax" }, { "name": "MaximumX", "value": "xmax" }, { "name": "YAutoTicks", "value": "false" }, { "name": "MinimumX", "value": "xmin" }, { "name": "MinimumY", "value": "ymin" }, { "name": "AxisXFont", "value": "\"normal normal 1vw\"" }, { "name": "AutoScaleY", "value": "false" }, { "name": "AutoScaleX", "value": "false" }, { "name": "Visibility", "value": "world" }, { "name": "XScalePrecision", "value": "0" }, { "name": "BRMessage", "value": "print?\"\":text" } ], "Children": [ { "Name": "source", "Type": "Shape2D", "Properties": [ { "name": "FillColor", "value": "\"Red\"" }, { "name": "SizeX", "value": "20" }, { "name": "ShapeType", "value": "\"WHEEL\"" }, { "name": "X", "value": "x" }, { "name": "Y", "value": "y" }, { "name": "SizeY", "value": "20" }, { "name": "PixelSize", "value": "true" }, { "name": "EnabledPosition", "value": "\"ENABLED_ANY\"" } ] }, { "Name": "vdrag", "Type": "Group2D", "Expanded": "false", "Properties": [ { "name": "X", "value": "x" }, { "name": "Y", "value": "y" }, { "name": "Visibility", "value": "_isPaused" } ], "Children": [ { "Name": "varrow", "Type": "Arrow2D", "Properties": [ { "name": "SizeX", "value": "vx" }, { "name": "MarkEndHeight", "value": "20" }, { "name": "LineColor", "value": "\"Magenta\"" }, { "name": "SizeY", "value": "vy" }, { "name": "MarkEndWidth", "value": "20" }, { "name": "LineWidth", "value": "2" }, { "name": "OnDrag", "value": "vy = 0;\ntimemax=(xmax-xmin)/vx;\n" }, { "name": "Offset", "value": "\"SOUTH_WEST\"" } ] }, { "Name": "vdragbtn", "Type": "Shape2D", "Properties": [ { "name": "SizeX", "value": "15" }, { "name": "ShapeType", "value": "\"WHEEL\"" }, { "name": "X", "value": "vx" }, { "name": "LineColor", "value": "\"Magenta\"" }, { "name": "PixelSize", "value": "true" }, { "name": "SizeY", "value": "15" }, { "name": "DrawFill", "value": "false" }, { "name": "OnDrag", "value": "vy = 0;\ntimemax=(xmax-xmin)/vx;\n" }, { "name": "EnabledPosition", "value": "\"ENABLED_X\"" } ] } ] }, { "Name": "image", "Type": "Image2D", "Properties": [ { "name": "SizeX", "value": "20" }, { "name": "X", "value": "xe" }, { "name": "Y", "value": "ye" }, { "name": "ImageUrl", "value": "\"./doppler/ear.gif\"" }, { "name": "Visibility", "value": "observershow" }, { "name": "SizeY", "value": "20" }, { "name": "PixelSize", "value": "true" }, { "name": "EnabledPosition", "value": "\"ENABLED_X\"" } ] }, { "Name": "obsvdrag", "Type": "Group2D", "Expanded": "false", "Properties": [ { "name": "X", "value": "xe" }, { "name": "Y", "value": "ye" }, { "name": "Visibility", "value": "observershow" } ], "Children": [ { "Name": "whatdoesthisdo", "Type": "Group2D", "Expanded": "false", "Properties": [ { "name": "Visibility", "value": "false" } ], "Children": [ { "Name": "observer", "Type": "Shape2D", "Properties": [ { "name": "FillColor", "value": "\"Blue\"" }, { "name": "SizeX", "value": "20" }, { "name": "ShapeType", "value": "\"RECTANGLE\"" }, { "name": "X", "value": "xe" }, { "name": "Y", "value": "ye" }, { "name": "SizeY", "value": "20" }, { "name": "PixelSize", "value": "true" }, { "name": "EnabledPosition", "value": "\"ENABLED_X\"" } ] } ] }, { "Name": "obsvvarrow", "Type": "Arrow2D", "Properties": [ { "name": "SizeX", "value": "vxobserver" }, { "name": "MarkEndHeight", "value": "20" }, { "name": "LineColor", "value": "\"rgba(0,150,0,1.0)\"" }, { "name": "SizeY", "value": "vy" }, { "name": "MarkEndWidth", "value": "20" }, { "name": "LineWidth", "value": "2" }, { "name": "OnDrag", "value": "vy = 0;\ntimemax=(xmax-xmin)/vx;\n" }, { "name": "Offset", "value": "\"SOUTH_WEST\"" } ] }, { "Name": "obsvvdragbtn", "Type": "Shape2D", "Properties": [ { "name": "SizeX", "value": "15" }, { "name": "ShapeType", "value": "\"WHEEL\"" }, { "name": "X", "value": "vxobserver" }, { "name": "LineColor", "value": "\"rgba(0,150,0,1.0)\"" }, { "name": "PixelSize", "value": "true" }, { "name": "SizeY", "value": "15" }, { "name": "DrawFill", "value": "false" }, { "name": "EnabledPosition", "value": "\"ENABLED_X\"" }, { "name": "OnDrag", "value": "vy = 0;\n_initialize();\n" } ] } ] }, { "Name": "wavesfront", "Type": "ShapeSet2D", "Properties": [ { "name": "NumberOfElements", "value": "n" }, { "name": "FillColor", "value": "\"rgba(255,255,255,0.0)\"" }, { "name": "SizeX", "value": "D" }, { "name": "ShapeType", "value": "\"ELLIPSE\"" }, { "name": "X", "value": "xs" }, { "name": "LineColor", "value": "\"Blue\"" }, { "name": "Y", "value": "ys" }, { "name": "SizeY", "value": "D" }, { "name": "LineWidth", "value": "2" } ] }, { "Name": "wavemeetobserver", "Type": "Shape2D", "Properties": [ { "name": "FillColor", "value": "\"rgba(255,255,255,0.0)\"" }, { "name": "SizeX", "value": "D[eid]" }, { "name": "ShapeType", "value": "\"ELLIPSE\"" }, { "name": "X", "value": "xs[eid]" }, { "name": "LineColor", "value": "\"Green\"" }, { "name": "Y", "value": "ys[eid]" }, { "name": "Visibility", "value": "vs\n
\n

Doppler Effect Sound Wave JavaScript Applet

\n\n

\n This simulation allows students to explore the Doppler effect for sound waves.\n It shows how the observed frequency and wavelength change when a sound source\n and/or observer moves relative to each other.\n

\n\n

\n When the source moves towards the observer, the wavefronts are compressed and\n a higher frequency is heard. When the source moves away, the wavefronts are\n spread out and a lower frequency is heard.\n

\n\n

Suggested Learning Activities

\n
    \n
  • Observe how the wavefronts change when the source is moving.
    • \n
  • Compare the sound heard in front of and behind the moving source.
    • \n
  • Explain why an ambulance siren sounds higher-pitched as it approaches and lower-pitched as it moves away.
    • \n
  • Investigate how changing the speed of the source affects the Doppler effect.
    • \n
\n\n

Credits

\n

\n Original model by Fu-Kwun Hwang, remixed by lookang.\n Compiled with WebEJS. Released under a Creative Commons Attribution licence.\n

\n
\n\n" } ] } ] } ], "RootProperties": [] }, "metadata": { "APP": "WebEJS", "CreatedWith": "WebEJS : The web version of Easy JavaScript Simulations", "MoreInfo": "WebEJS 1.1", "version": "https://www.um.es/fem/wikis/webejs/" } }