# Uncertainty of a ticker timer

1. Mar 3, 2009

### alexsb92

Hey everyone,

First off, hopefully I am in the right topic.

Now i just had a lab last week, where we had to calculate acceleration and talk about motion using data we got from a ticker timer. One of the requirements of the report is to find and talk about uncertainty of the ticker timer. The ticker timer is a 60 Hz one so it *should* tick 60 times a second. I was thinking first that there might be some fluctuations of the power, but i realized that there may be some machines a lot more sensitive to fluctuation of the current, and the teacher told me i was right, so it should therfore be something regarding the fact that it doesn't tick 60 times a second, but why?

If i ddin't use proper scientific terms would you also kindly correct me?

Thanks!

2. Mar 3, 2009

### Delphi51

Variation in frequency on a power line is very small. I recall watching a frequency meter at a power plant while on the night shift, and unless lightning took out a generator the frequency never varied as much as a tenth of a per cent.

Consider for a moment the accuracy in measuring the dots on the tape. I suspect you only measured to the nearest mm. (Don't feel bad - the size of the dots probably makes it impossible to do better.) If you then calculated the distance between two dots each plus/minus half a mm, you have plus or minus a full mm on your delta d. If you calculate velocity as v = delta d/delta t, where delta t is 1/60 second, your velocity is plus or minus 60 mm/s. That may be your most important error.

If things got going really fast and your dots became slide marks, much more error.

3. Mar 3, 2009