Play and Learn 2

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***** U S E R M A N U A L ***** P E N D U L U M IBM PC Version 1.0 (a shareware program) by P.Thieberger 15 Seeley St. Brookhaven, NY 11719 "Peter Thieberger a member of the Association of Shareware Professionals (ASP). ASP wants to make sure that the shareware principle works for you. If you are unable to resolve a shareware-related problem with an ASP member by contacting the member directly, ASP may be able to help. The ASP Ombudsman can help you resolve a dispute or problem with an ASP member, but does not provide technical support for members' products. Please write to the ASP Ombudsman at 545 Grover Road, Muskegon, MI 49442 or send a CompuServe message via CompuServe Mail to ASP Ombudsman 70007,3536." ************************************************************************ Note: This is an abbreviated manual. When you order your registered copy of the program, you will receive a printed manual containing much additional information, an easy derivation of the pendulum formula, a section on computer simulations, and an Instructor's Guide. The Instructor's Guide contains sections on the following subjects: 1) Teaching with PENDULUM. 2) HELP SCREENS: Possible modifications or creation of new ones. 3) Additional problems, questions and assignments. 4) A lesson on computer simulations. ************************************************************************ INTRODUCTION The pendulum is one of the simplest, best known, and most used mechanical devices. Understanding in detail how it works and why it behaves the way it does will be an important step in your understanding of more complicated systems. In learning about the pendulum you will also start to appreciate the need for more advanced mathematical tools to describe such systems. With this program you will be able to create and modify computer simulated pendulums, you will move their suspension points and see how they react. You will measure the length and the oscillation periods and compare your results with calculations. You will actually perform computer "experiments" but it is very important that you also perform experiments with real pendulums to acquire a good feeling for mechanical systems and for experimental methods. Airline pilots use computer based flight simulators for part of their training but surely you wouldn't like to find out that they don't do anything else ! One thing computer simulations allow you to do is to create conditions which you couldn't easily achieve in reality. For instance, this program allows you to change the gravitational acceleration g and therefore you can see what a pendulum would do on the moon without the need for space travel. You can even find out what would happen if g could become negative! Other aspects which are not so easy to study with a real pendulum are the behavior for very large oscillation amplitudes or for cases when the friction is very large or very small etc. These "extreme" conditions are not only fun to observe, but they often give you a better understanding of what is going on under more "normal" circumstances. Other computer based simulations such as the above mentioned flight simulators are also used to create extreme conditions which one couldn't, or wouldn't want to create in reality. There is a section of this program showing a moving pendulum with attached force and acceleration vectors which is a big improvement over the static diagrams you find in books. You will also see a dynamic graphical representation of position, velocity and acceleration plotted as functions of time and you can stop the action at any instant and read all the values. Carefully examine these moving diagrams and graphs to gain a better understanding of how and why the pendulum moves as it does. Finally, the program contains problem generators and assignments in which all the numerical values are changed for each run. You will solve interesting problems requiring measurements and calculations and you will see examples of how pendulums can be put to good use. You will enter your answers and the computer will tell you whether they are right or wrong. - 1 - HOW TO GET STARTED I will first show you the easiest and fastest way to run the program directly from the floppy disk. If you also have a hard disk you may later want to use it instead. In Appendix A you can find instructions on a couple of different ways to copy the necessary files to the hard disk. It is in general a good idea to make a back-up copy of your floppy disk especially if you plan to run the program repeatedly from that disk. Please see Appendix B for instructions on how to make copies of this program for back-up purposes of for distribution to other users. This is a shareware software product, and we rely on users to order their own, registered, copies should they find the program interesting and useful. Now do the following: 1) Insert the floppy disk in the floppy disk drive which we will assume is drive "A" and close the door or lever. (If the floppy disk drive you are using is "B" instead, then change all the "A"s to "B"s in these instructions.) 2) If there is any program running on your computer, terminate it by using the command(s) appropriate for exiting or ending that program. 3) If the computer has more than one disk drive, type a: followed by pressing the "ENTER" key. In what follows we will symbolize the pressing of "ENTER" by the symbol <- ; so we will simply say: type a:<- . If you don't know whether there is more than one drive type a:<- anyway to ensure that A be the active drive. 4) Now type PENDULUM <- and, if you have a registered copy, the program will start in a few seconds with a nice display on the screen. This display will disappear by itself and you will see the main menu. If you want to reach the main menu sooner, all you have to do is to press any key and the menu will appear almost immediately. If your copy of the program is not registered, you will first see a couple of screens telling you the number of times you have run the program, asking you to get your own registered copy, offering ordering information and encouraging you to make as many copies as you like for your friends. - 2 - HOW TO "NAVIGATE" THROUGH THE PROGRAM This program, like most other computer programs consists of several different sections and you will see different screen displays in accordance to which section is active at the time. The MENU is the origin for selecting the various available sections. This is where the program starts and you can always go back to the MENU to make another selection. The MENU screen display looks as follows for this program: ***************************************************************** <<<<<< P E N D U L U M >>>>>> Copy registered to John Doe ╔═════════════════════════════════════════╗ ║ * E X P E R I M E N T * ║ ║ * A N A L Y S I S * ║ ║ * P R O B L E M S L E V E L 1 * ║ ║ * P R O B L E M S L E V E L 2 * ║ ║ * P R A C T I C E * ║ ║ * L O S T I N S P A C E * ║ ║ * S H O R T R U N W A Y * ║ ║ * M O O N E S C A P E * ║ ║ * Q U I T * ║ ╚═════════════════════════════════════════╝ To select, use the arrow keys and then press <ENTER> or press one of the highlighted characters Figure 2. ***************************************************************** The labels you see inside of the rectangle in Fig. 2 are the different available options. To select one of them you can use one of two methods: a) Use the up or down arrow keys to position the horizontal bar on the item you want, and then press the <ENTER> key. or b) Press the key indicated by the emphasized letter contained in each of the labels. At the bottom of each of the screens selected from the main menu you will find abbreviated instructions to remind you of which keys to use. Those abbreviated instructions which are not totally self explanatory are described below for the different sections: - 3 - a) EXPERIMENT Section INSTRUCTION MEANING F3,4:L=0.9m Use the function key F3 to decrement, and F4 to increment the length L of the pendulum. As long as you keep one of these keys depressed the value of L will continue changing until a maximum or minimum value is reached.The value of L is 0.9 meters in this example. F5,6:g=9.8m/s^2 Use the function key F5 to decrement, and F6 to increment the gravitational acceleration g. The value of g is 9.8 meters per second squared. F7,8:friction=10 Use the function key F7 to decrement, and F8 to increment the friction at the suspension point of the pendulum. The present value of the friction, in arbitrary units, is 10. F9:timer Pressing the F9 function key will start the timer and you will see the word TIMING displayed at the top right corner of the screen. Pressing F9 again will stop the timer and you will see the elapsed time in seconds at the top right corner. Pressing F9 once more will reset the timer to 0.0s. b) ANALYSIS Section INSTRUCTION MEANING F2:mass ─┐ │ F3:amp. │ These instructions mean that each of the │ listed quantities can be switched back and F4:length │> forth between two preset values by using the │ corresponding function key (amp. stands for F5:g │ amplitude and g for gravity). The friction │ is turned on and off by pressing F6. F6:friction │ ─┘ F7:stop Pressing F7 stops the action and displays the instantaneous value of several variables in the lower right part of the screen. - 4 - c) PROBLEMS (levels 1 and 2) INSTRUCTION MEANING F1:help The upper right section of the screen will show a list of symbols and their meanings for the variables used in this problem. Pressing F1 again will restore the graphic normally seen in that section of the screen. F4:hint The upper right section of the screen will show an equation that can be used for solving the question being asked. Using a hint will result in a slight reduction of the final score. F8:mode Used to toggle between the "normal" mode where questions are asked in a random order, and "easy" mode where questions are sequenced so as to provide the required values for each subsequent step. d) ASSIGNMENTS These are the 5th through 8th options of the menu. They are called PRACTICE, LOST IN SPACE, SHORT RUNWAY, and MOON ESCAPE. In each case a short description of the assignment is given at the very top of the screen. The use of the function keys, mentioned at the bottom of the screens are the following: INSTRUCTION MEANING F1:HELP This command will lead to one or more screens containing detailed descriptions of the assignments as well as instructions and suggestions. F2:enter your answer A screen will be shown with the questions asked by this assignment. Make this selection after you have worked out your answers. You can always come back to the main screen and repeat the assignment, but each time you do, the numeric values of the problem will have changed. - 5 - F7,8:friction=10 Use the function key F7 to decrement, and F8 to increment the friction at the suspension point of the pendulum. The present value of the friction in arbitrary units is 10. Use this feature for stopping the pendulum when you must measure its length, or to reduce the amplitude before measuring the period. F9:timer Pressing the F9 function key will start the timer and you will see the word TIMING displayed at the top right corner of the screen. Pressing F9 again will stop the timer and you will see the elapsed time in seconds at the top right corner. Pressing F9 once more will reset the timer to 0.0s. RUNNING THE PROGRAM WITH OR WITHOUT A MOUSE You will be able to move the suspension point of the pendulum in all the sections of this program except in the "ANALYSIS" and the "PROBLEM" sections. If your computer has a "mouse" as a pointing device the program will use it to let you move the suspension point to any position on the screen and to initiate the oscillations. It is a real advantage to have a mouse for running this program because you can actually control the pendulum with motions of your hand. This gives you a realistic sensation of how the pendulum reacts. If your computer doesn't have a mouse the program will automatically allow you to use the arrow keys to move the pendulum suspension point. You will get an accelerating motion of the suspension as long as you press the arrow key, and a sudden stop when you release it. This will of course cause the pendulum to oscillate when the motion is horizontal. For easier adjustment of the oscillation amplitude you can also press the space bar to stimulate the oscillations. - 6 - APPENDIX A HOW TO INSTALL THE PROGRAM ON THE HARD DISK If your computer has a hard disk you can make a directory for the PENDULUM program and copy all the files from the floppy disk to that directory. From then on all you need to do each time you want to run the program, is to change to that directory and to type PENDULUM <- . An easier and better procedure for installing the PENDULUM files is by using the INSTALL program which is on your floppy disk. This procedure is described in detail below: 1) If there is any program running on your computer, terminate it by using the command(s) appropriate for exiting or ending that program. 2) Insert the PENDULUM floppy disk in the floppy disk drive which we will assume is drive "A" and close the door or lever. (If the floppy disk drive you are using is "B" instead, then change all the "A"s to "B"s in these instructions.) 3) Now, type A: followed by pressing the "ENTER" key to ensure that the appropriate disk is active. (In what follows we will symbolize the pressing of "ENTER" by the symbol <- ; so we will simply say: type A:<- ). 4) Now type INSTALL <- and the "INSTALL" program will start by asking you for a directory name to use on your hard disk. If you don't answer this question and just press <- , then the directory C:\PENDULUM will be created and used. If C:\PENDULUM already exists and contains old files, the program will request your permission to delete the old files. If you don't want to use C:\PENDULUM, or if your hard disk is D instead of C, then enter any other valid directory name such as D:\PEND <- . You can also use subdirectories. If for instance C:\PHYSICS already exists, you can enter C:\PHYSICS\PENDULUM <- to store your files in a subdirectory of PHYSICS called PENDULUM. 5) After a short while, you will see a message on the screen telling you that the installation is complete, and you will be asked, at the bottom of the screen, if you want to run the program now. If you answer y (for yes) the program will be loaded and run from the hard disk. 6) From now on you will not need the floppy disk and all you need to do to run the program is to choose the directory where the PENDULUM files are, and then type PENDULUM <- . For example, if the directory is C:\PENDULUM , you first type C:<- to ensure that the C is the active drive, then you type cd \PENDULUM <- to choose that directory and finally type PENDULUM <- to start the program. - 7 - APPENDIX B HOW TO GET A REGISTERED COPY AND HOW TO DISTRIBUTE THE PROGRAM If the copy of PENDULUM you have is not registered, we would like you to try it and to see if you find it interesting and useful. If you do, I hope you will use the easy ordering instructions you are offered when running the program. For a very modest price, you will receive the latest version of the program and a more extensive printed manual, containing additional explanations and an INSTRUCTOR'S GUIDE. You will also be informed about future upgrades and about our new educational programs. Finally, purchasing the program, you will contribute to further software developments and to making the "shareware" system work. You are welcome to make back up copies of PENDULUM for yourself and also to distribute copies as widely as you like, whether your copy is registered or not. The copies you distribute for use on other computers must contain all the files and be identical to the original you received, or they will not run on other machines. Copies of a registered version of PENDULUM will automatically become unregistered when run on a different computer. We will consider two cases for making copies. The first one is for systems having at least two disk drives and the second one is for systems having only one. Case 1: SYSTEMS WITH TWO DISK DRIVES If you have a hard disk on which you installed the PENDULUM files (see appendix A), or if you have two floppy disk drives then the easiest way for making copies is to use the INSTALL program. In either case use the DOS cd command to change directory to the one containing the PENDULUM files, and then type INSTALL <- . When asked for the destination directory type either a:<- or b:<- depending on where you want the copy to be generated. Whichever drive you choose must of course contain a blank, and previously formatted floppy disk. Case 2: SYSTEMS WITH ONLY ONE DISK DRIVE 1) Terminate any program that may be running and then type: diskcopy a: b:<- . 2) Now follow the instructions which you will see on the screen. When the computer instructs you to insert the "source" disk it means the disk from which you are copying; namely in this case the original PENDULUM disk. When you are instructed to insert the "target" disk it means an empty disk on which the copy will be written. (This empty disk does not need to be previously formatted). 3) You may be instructed to swap diskettes several times depending on the size of the memory. When finished, the computer will prompt you with the following message: Copy another diskette (Y/N)? Type N (for NO) to terminate the procedure or Y (for YES) if you want to make more copies. - 8 -