Ticker Tape Timer

1. Ticker Tape Timer

2. What is a TTT? • A ticker tape timer (TTT) is an electrical motor connected to Alternating Current (AC) of the wall socket. • AC is electric current that “Flips” +/-. • In the wall socket case the AC produced there is 60 Hz. • Hz is Hertz a unit to measure frequency. What it measures is how many times an event occurs in one second. • 60 Hz means that the current flips +/- 60 times in one second.

3. TTT Cont. • The motor on the TTT is connected to a hammer. Since the frequency is 60 Hz this means the hammer will hit 60 times every second. • That is fast! • It is also uniform! • When a strip of ticker tape is pulled through the timer this is what it looks like. • The time of each dot is constant the distance between the dots depends on how fast the tape is pulled through the timer.

4. Strip Examples A B C C: Greater distance between dots that have the same time is a greater speed. Which strip is pulled Fast? B: Small distance between dots that have the same time is a slower speed. Which strip is Slow? Which strip is medium? A: Medium distance between dots that have the same time is a medium speed.

5. What about this one? Slow then fast then slow again. This is Non Uniform

6. Ticker Tape Advantages • Exact place and time measurements. • Have a permanent record that can be reused. • The dots happen at a regular rate of 60 hits every second. This means if you count out 60 spaces and dots this is the time of one second (60 dots = 1.0s). That is not to manageable so to make it easier we divide by ten and we have 6 spaces and dots happening every 0.1 s (6 dots = 0.1s). • This is the amazing part. We can see what happened in every tenth of a second.

7. 1 2 3 4 5 6 Count out six dots from the last dot. This is the next 0.1 s 1 2 3 4 5 6 Count out six dots from the first dot. Do not count the first dot. This is 0.1 s. End section 1 Start section 2 End section 2 Start section 1 TTT Analysis • We can measure 0.1 s every 6 dots. This is a very accurate time measurement. Lets see an example: Measure the displacement from the first dot. Let us say this one is 8.0 cm Measure the displacement from the last dot of the first part. Let us say this one is 9.0 cm

8. TTT Analysis Continued • In section one there is 8.0 cm of displacement over a 0.1 s interval of time. • We know that the speed can be found by using: • Since the time is so small then when we calculate speed here we are calculating instantaneousspeed

9. Calculation This is the same as multiplying by 10

10. You TryTTT Lab • Purpose: To determine if pulling a ticker tape throughout the timer is uniform or non uniform motion? • Theory: (What you need to know to do and understand the lab) • You fill this out • Procedure: • Take a piece of ticker tape about a meter long. • Insert it into a timer. Under guide 1 over carbon but under hammer and under guide 2 • Turn on timer • Pull tape through at a fairly fast pace and try your hardest to be uniform. (Not too fast to rip paper, you must have at least 60 dots/10 sections, you can stop analyzing after 15 sections.) • Mark the first dot that can be seen clearly. Write START on the tape. • Count six dots over and mark with a line. Repeat till the end of the tape.

11. TTT Lab Continued • Measure the distance between the marks and record in a data table. • Determine the interval speed, total time, total distance and average speed for each section and record in the data table. • Show sample calculations. • Analysis: • 1.) Was the motion of the tape Uniform? Explain • 2.) Can you find sections of the tape that are uniform and non-uniform? Describe where these sections are and what they look like. • 3.) Are the instantaneous speed values uniform? Explain • 4.) Are the average speed values uniform? Explain • 5.) Compare and contrast the instantaneous and average speed values. • Write a Conclusion: • Restate purpose in past tense, describe at least 3 key observations/data that will support your conclusion. Write a conclusion that answers the purpose.

12. Sample Data Table