# Yet Another Simple Measurement1

## Discussion:

Ok - no fooling around this time. I've certainly learned my lesson! This is serious! Everyone will use the same ruler this time, by golly...

In this activity, you will individually measure the length of an object supplied by your teacher. Then you will compare your measurement with your classmates' measurements and decide on the best estimate of the object's length.

Before you attempt this activity, be sure that you have read the material on measurement - particularly "How to Analyze a 'Measure the Value of ...' Experiment".

## Equipment:

Per class:
 an object to measure (supplied by your teacher) a metric measuring tape

## Procedure:

1. Before your begin, write a brief description of this activity in your lab notebook.
2. When it is your turn to measure the object, record your measurement in your lab notebook in a data table similar to the data table below. Use the number of significant digits that you feel is appropriate.
3. Write your name and result on the board as directed by your teacher.
4. Record your classmates' measurements in your lab notebook.

## Results:

1. Your teacher will tell you when and how to report your measurement on the board.
2. Discuss the class' results with your classmates. Come to an agreement on a best estimate for the length of the object, including the appropriate number of significant digits to use.
3. Calculate and record an uncertainty interval for your best estimate.
4. Your teacher will tell you the "accepted value" of the length measurement. Record it in the data table.
5. Calculate a "t-score" for the class'best estimate and the accepted vallue.
6. Calculate and record the percent of difference between the class' result and the accepted value.
7. Discuss these results with the class.

## Conclusions:

In your lab notebook, record the results of this activity, as well as any other results or conclusions reached by the class. Also, answer the following questions:

1. Based upon our criteria, how well does the class' measurement agree with the accepted value? Why do you think this happened?
2. How did the measuring tape affect the precision of your results?
3. How did the measuring tape affect the accuracy of your results?
4. Was there any random uncertainty in the measurements of this activity? How did it arise?
5. Was there any systematic uncertainty in the measurements of this activity? How did it arise?

1based on "Activity 2: Measurement with the ... Meterstick" in the Pasco Significant Figures Set (ME-9849)
last update June 6, 2005 by JL Stanbrough