Circle Measurement and Ratio Lab Report

Circle Measurement and Ratio LabObjective: Practice measuring and calculating using the metric system.
Note: Students are allowed to do this lab individually or with a partner. If with a
partner, both partners must write and submit their own labs and indicate who their lab
partner was. Labs write-ups should not be identical otherwise it is considered
plagiarism. Lab write-up format is given in the syllabus.
Materials Required:
8 circular objects
String or tape that can wrap around the outside of the circular objects
Metric ruler
Calculator
Steps:
1. Use the following table to record the measurements and the calculated ratio
of the (outside distance)/(inside distance) of the 8 circular objects as directed
in the following steps. Record all measurements in cm. The calculated ratio
will have the units of cm/cm which cancel each other; therefore the ratio will
have no unit.
Circular Object # Outside Distance Inside Distance
Ratio =
(cm)
(cm)
Outside/Inside
1
2
3
4
5
6
7
8
2. Use string or tape to wrap around outer edge of circular object.
3. Mark or cut to indicate where tape or string meets the other end. Accuracy is
very important for good results.
4. Remove and then measure the tape or string to find out what the outside
measurement of the circular object is. Record in table for Object #1.
5. Using the string or tape, measure across the center of Object 1 to both
outside edges where the string was placed in Step 2 and as shown in drawing
6.
7.
8.
9.
by blue line. Note if there is a thickness to outer edges, string must go to
outer edge. Record Inside value for Object 1.
Repeat steps 2-5 for objects 2 through 8. If partners, each partner is to
measure 4 of the objects.
The Ratio column is for the ratio of the outside of a circle to the inside
(ratio=outside/inside). Calculate the ratio for each object and record to
decimal places (example 2.98).
The ratio of the outside of the circle to the inside remains constant and
therefore all of object ratios should be similar. Ratios will not be exact
because this is an experiment, but all should be close to each other. If not,
try to find out why by measuring the object again. In real life if a test case
had very different results and cannot be run again, the result may be
considered flawed and discarded.
Average the ratios of the objects and record.
Questions to Answer:
1. Does this average of the ratios look familiar?
2. What are the outside distance around a circle and the inside distance across
the center of a circle called by mathematicians?
3. Where is the radius of a circle located? (Describe what radius means)
4. How many radius distances go across the inside distance across the center of
a circle?
5. What are the mathematical equations involving a circle? Do any of them have
a correlation to the experiment you just performed?
6. What variable is generally used in math to represent the ratio you have just
calculated?
7. What number is used by mathematicians to represent the ratio of the
outside/inside a circle?