Name______Physics Lab: Rhinebeck High School
Getting to know the “clapper”
In this lab, you will become more familiar with the device commonly referred to as the “clapper”. It is formally known as a recording timer and it is used in detailed motion labs to precisely record the positions of a moving object at particular times.
OBJECTIVES
Cooperatively collect and process data Become familiar with the operation of the clapper Learn the recording frequency of the clapper Learn about alternating current provided by good old Central Hudson Apply the concepts of uncertainty, precision, accuracy and percentage error
PRELIMINARY QUESTIONS
1. What is a period (T) ?
2. What is frequency(f)?.
3. How are frequency and period related?
4. What is the assumed frequency of the alternating current in the US?
5. What happens to the precision of data that is calculated using a larger sample size? (Remember in the previous lab with the larger page samples; 50,100, 200?)
MATERIALS A clapper Calculator Roll of ticker tape C – clamp
Rhinebeck High School Physics Clapper Lab
Stop watch
GENERAL PROCEDURE 1. Make sure that your clapper has a good carbon disc. If it looks worn out, ask Mr. Britton for help. 2. Clamp your clapper down to the table with the C-clamp. Don’t over tighten. Plug in the clapper to an outlet. Avoid creating a tripping hazard with your power cord. Report any frayed or severed wires to me right away. 3. Rip off a ~1 meter length of the ticker tape. Insert one end into the clapper. Make sure the ticker tape is in between the carbon discs. 4. Turn on the clapper, it should vibrate and buzz. 5. Pull the tape through the clapper at a moderate speed and then inspect the dots. Be sure they are clear and easy to count. If the dots are not clear. Look for obvious problems and try to fix. If this doesn’t work, ask Mr. B for a hand. 6. Once your clapper is set up correctly, rip off a ~ 2- 3 meter length of ticker tape. Insert it into the clapper correctly. 7. The group timer should hold the long end down on the lab table while the puller keeps tension on the ticker tape. When the timer person is ready to hit the stopwatch start button, they say GO and let go of the tape and hit the start button. The pull should pull the tape through at a steady moderate speed. The timer should simultaneously hit the stop button and slam their hand down on the moving tickertape to stop it when the reading is around 3 second ± 1 second. If the run is good, write your names and the stopwatch time for that run on the tickertape. The dots can now be counted and recorded in the data table. 8. Keep repeating #7 until you get 5 good tapes. Note: follow all uncertainty and rounding rules in the data display: Attach your work to this lab when you hand it in Trial # of counted Time Period (T) Frequency (f) dots include uncertainty include uncertainty include uncertainty include uncertainty Units: 1
2
3
4
Rhinebeck High School Physics Clapper Lab
5
Average Frequency Calculate the average Be sure to omit any frequency and uncertainty bad data from your average. Record at right*
Display with uncertainty Construct a number line to show how your average frequency includes (or does not include)the accepted value of 60.0 Hz:
Note: Number line criteria: scaling, units, , use of straight edge, uncertainty correctly displayed.
Calculate percentage error
Questions:
1. What would occur to your results if the tape was pulled very slowly over the same 3 second time? (explain in terms of precision and accuracy)
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Rhinebeck High School Physics Clapper Lab
2. What would have occurred to your results if you took data for about 6 seconds instead of 3 seconds? (explain in terms of precision and accuracy)
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3. If your average frequency was above or below 60.0 Hz, discuss and write down some plausible explanations for what may have occurred. Be specific and support your explanation. Make sure your explanation is consistent with the data.
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3. Draw a sketch of tickertapes for the following scenarios: a. Pulled slowly(constant)
b. Pulled quickly(constant)
Rhinebeck High School Physics Clapper Lab
Rhinebeck High School Physics