7BOBO-áødHHHHHHÐ-á<H-á¨-áèN÷ -át -ZÔlÿÿ`kxHHÚ(ÿáÿâùFG(üHHÚ(d'@ÿÿ-»´†l `/±ã:CKx’-á@-á$‰Œàxx€\*‰Œÿÿ  -Ÿ| -£„  -«” -¯œ-âx-·¬:ã-¿9væ *ŠdúŠ€-áH!ÿÿÿÿÿÿÿÿ4 }ýDSETŠ*‚:k<-â-áü-á´Ôˆ-â/ˆøÔˆ-â¸.|“Ôˆ-à<#èX%&HIhi›œ»¼æçpßàÝvw´é)4?JçpøŠØÙñò   ‘ Å È  < s t ¶ í $ % e œ Ó Ô ä å ( c ž Ù Ú # B C t “ ” ÖLMÐ  !"STޱõ!"#$%&'()*+,¨©ò*+5689X   q | á V á ÿ   å è   % J z ~  ‘ ” è é   q r t } ø ù ü ‹ Ž Ø Ù Ú ó  Õ  æ  é   # X Y † ‡ Ž ” ° · ÷  * , 3 8 9 9 2É-â É-âœÉ-ãÄ É-â$ Êq-âÉ NAME__________________________ DATE______________________ PERIOD________________ UNIT 1: LEARNING PROBLEM-SOLVING TECHNIQUES LABORATORY ACTIVITY 3 DESIGNING A TIME-MEASURING DEVICE INDIVIDUAL DATA SHEET You would like to design a simple device for measuring short periods of time. The device is to be rugged, portable, and inexpensive. You learn from your friend, who is taking a physics course, that a pendulum of a fixed length always takes the SAME time for a complete back-and-forth swing. You have a plumb line and decide to use it as a pendulum. FIND: The length of line that will give you a complete swing lasting approximately 1 second. NOTE: Measure the length of the string that swings. Provide a clear swinging path for 3 to 12 inches of string, with a stable tie-down point at the top (for example, tie it to the back of a chair, or drape it over the edge of a table.) How to count a complete swing: A complete swing (as illustrated) is a Òback and forthÓ cycle. So the counting procedure will be as follows: Pull the weight back a few inches, release and start timer The weight will swing away and return -- count one The weight will swing away and return -- count two --- --- --- --- The weight will swing away and return -- count ten and stop timer. * Use the stopwatch to measure the time required for10 complete swings. * Divide this time by 10 to get the time of one complete swing. This time is called the pendulumÕs period. * Vary the length from 3 inches to 12 inches, in increments of 1 inch, and  determine the period for each length. * For each length record the following in a table: the pendulum length , the time for 10 complete swings, and the period in seconds. * Have someone in your group agree to do 50 chair-stepping exercises (stepping onto and off of a chair 50 times). Use your pendulum -- 10 inches in length -- and a stopwatch to measure how long the exercise takes. Compare the result of your pendulum clock to the result of the stopwatch. How did your clock do? Understand the problem 1. What are you trying to find? I am trying to find:___________________________________________ ________________________________________________________ 2. What data do you now have to solve the problem? a. Why are you using a pendulum?__________________________ ___________________________________________________ ___________________________________________________ b. What features make a pendulum an advantageous device to use? ___________________________________________________ ___________________________________________________ c. How can a pendulum be used as a timing device?____________ ___________________________________________________ ___________________________________________________ Develop a plan 1. What additional information do you need to solve this problem? ________________________________________________________ ________________________________________________________ ________________________________________________________ 2. Does finding any of this information involve solving other problems? Yes or No?___________ 3. Are there any graphical methods you can use? Yes or No?___________ 4. What mathematical methods can you use?____________q___________ ________________________________________________________ ________________________________________________________ 5. What equipment is available that you can use to find the needed information?______________________________________________ ________________________________________________________ Carry out the plan 1. Solve the problem, showing all of your work. a. MAKE A TABLE FOR THE DATA GATHERING (worth 10 pt.s!) (First one is done for you.) String Length (inches) Time for 10 swings Time for 1 swing 3 5 sec 0.5 sec b. What length of line will give you a complete swing lasting approximately 1 second?_______________________________ 2. Can you make a rough estimate for any or all parts of the solutions? Yes or No?_________________ Check the results DSET|ÿÿ(Hÿÿÿÿÿÿ-á8Ôˆ>"9 ˆÔ*6ÿÿ*>"9DSET|ÿÿ(Hÿÿÿÿÿÿ-á09ˆÔ>Â96ÿÿ*=Þ9