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Screen output
The text shown in Figure 13 should appear in your browser window when the html file is opened in your browser.
| Figure 13 . Screen output for Listing #4. |
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Start Script
Platform velocity magnitude = 3.70 miles/hourPlatform velocity angle = 22.50 degrees
Man velocity magnitude = 4.83 miles/hourMan velocity angle = 45.00 degrees
End Script |
Analysis of the code
The velocity of the platform relative to the ground is the vector sum of the ship's velocity and the velocity of the platform relative to the ship. The man's velocity is the vector sum of theplatform's velocity relative to the ground and the man's velocity relative to the platform.
Listing 4 begins with copies of the getAngle function and the vectorSum function, which I have already explained. This discussion begins at the commentthat reads "Main body of script begins here."
The main body of the script
The main body begins with the declaration and initialization of six variables whose contents represent the magnitude and the angle of the ship, theplatform, and the man.
Add the first two vectors
The vectorSum function is called to add the ship's velocity vector (relative to the ground) and the platform'svelocity vector (relative to the ship). The resultant vector produced by adding those two vectors is stored in the array-object variable named platformVel for use later. This is the platform's velocity vector relative to the ground.
Add the man's vector to the sum
Then the vectorSum function is called again to add the platform's velocity vector (relative to the ground) andthe man's velocity vector (relative to the platform). Note that the two values stored in the platformVel array object are extracted and passed as parameters to the vectorSum function.
The resultant vector produced by that addition is saved in the array-object variable named manVel . This is the man's velocity vector relative to the ground.
Display the results
Finally, the method named document.write is called four times in succession to extract and print the four values stored in the two array objects, producing thetext output shown in Figure 13 .
Figure 14 through Figure 17 below are non-mirror-image versions of Figure 3 , Figure 6 , Figure 9 , and Figure 12 respectively.
| Figure 14 . Non-mirror-image contained in the file named Phy1070a1.svg. |
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| Figure 15 . Non-mirror-image contained in the file named Phy1070b1.svg. |
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| Figure 16 . Non-mirror-image contained in the file named Phy1070c1.svg. |
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| Figure 17 . Non-mirror-image contained in the file named Phy1070d1.svg. |
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I encourage you to run the scripts that I have presented in this lesson to confirm that you get the same results. Copy the code for each script into atext file with an extension of html. Then open that file in your browser. Experiment with the code, making changes, and observing the results of your changes. Makecertain that you can explain why your changes behave as they do.
I will publish a module containing consolidated links to resources on my Connexions web page and will update and add to the list as additional modulesin this collection are published.
This section contains a variety of miscellaneous information.
Financial : Although the openstax CNX site makes it possible for you to download a PDF file for the collection that contains thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
You also need to know that Prof. Baldwin receives no financial compensation from openstax CNX even if you purchase the PDF version of the collection.
In the past, unknown individuals have copied Prof. Baldwin's modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing Prof. Baldwin as the author.Prof. Baldwin neither receives compensation for those sales nor does he know who doesreceive compensation. If you purchase such a book, please be aware that it is a copy of a collection that is freelyavailable on openstax CNX and that it was made and published without the prior knowledge of Prof. Baldwin.
Affiliation : Prof. Baldwin is a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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