Design
Research Question/Problem
How does the number of rubber bands in a rubber band chain affect how far each rubber band
stretches?
Variables
Independent - number of rubber bands
Dependent - distance the rubber band stretches (cm)
Control - type of rubber bands, screwdriver, height from where the screwdriver was dropped
Materials
-
2 Measuring tape (1.5 m)
-
Duct tape
-
Video Camera
-
15 Rubber bands that are 6.7 ± 0.1cm in length when flat
-
89 ± 1 g Screwdriver
-
523 ± 1 g Weight to straighten measuring tape
-
10 ± 0.1 cm Platform
Procedure
1.
2.
Duct tape both measuring tapes together, overlapping 1 cm at each end
Duct tape measuring tape to screwdriver at the 5 cm mark
3.
Duct tape platform to a surface approximately 10 feet off the ground so
that it sticks off approximately 7 cm
4.
Clip weight to the end of the measuring tapes
5.
Get partner to stand at the bottom, get ready to video record with
video recorder level to the measuring tape at the level the screwdriver
will drop
6.
Tie a rubber band to the middle of the screwdriver and add 10 rubber
bands in a chain to the end of the rubber band around the screwdriver
7.
Put the end of the rubber chain in the ridge at the end of platform so
that it doesn’t fall out
8.
Place the screwdriver directly in front of the platform horizontally so
that the end of the screwdriver touches the end of the platform
9.
Start recording on videorecorder
10.
Drop the screwdriver
11.
Stop recording after first drop
12.
Repeat steps 7-11 three additional times
13.
Repeat steps 6-12 with one additional rubber band after step 12 until
14 bands used
14.
Look
at
the
video
recordings
frame
by
frame
and
see
where
the
screwdriver reaches its minimum point.
15.
Record where the bottom of the rubber band tied to the screwdriver
lined up with the measuring tape in cm for every trial
Data Collection and Processing
Raw Data
Processed Data
Conclusion and Evaluation
Conclusion
Our data from this experiment shows that generally, an increase in the number of rubber bands in
the chain of rubber bands causes the stretch of each individual rubber band to increase. This is
due to the chain becoming longer with each additional rubber band, causing the screwdriver to fall a
longer distance and time, thus the screwdriver is able to have more time to accelerate to a higher
maximum speed. However, this data is not absolutely conclusive due to our set of trials with 12
bands showing a decrease in individual rubber band stretch from 11 bands. This can be due to the
uncertainty of our measurements causing discrepancies in our data. We had systematic error in our
uncertainty of measurements and random error when occasionally the rubber bands got tangled
together, causing the rubber bands to stretch less. When this happened, we did another trial, not
discarding the previous trial with the error.
Evaluating Procedure
We could have improved our procedure in making our measurements more accurate by using a
contraption that would ensure that the screwdriver would be dropped from the exact same height
every trial. In addition, it would have helped if we had used a heavier object to hang from the
rubber bands because doing so would have given us a larger stretch, and possibly larger differences
in the different numbers of rubber bands. In addition, our results were probably not as accurate
as they should have been due to the uncertainty that the partner would hold the videorecorder in
the same place level to the drop of the screwdriver like a stand would have.
Improving the Investigation
We could have improved our investigation in making it more reproducible by choosing metric weight
blocks instead of a random tool with a random weight. We also could have made a contraption that
would ensure that we dropped the screwdriver from the exact same height in every trial. If we had
put the video recorder on a stand, we could have also ensured more accurate and precise
measurements. In addition, we should have added more sets of trials in which we used different
numbers of rubber bands, possibly with a higher difference in number of bands between each set
i.e. using 5 rubber bands in set 1, 10 rubber bands in set 2, and so on. This would have made our
results more valid and allow us to make a better conclusion because our current results show that
the increase in each rubber band stretch is very close.
This would have also helped our data
because it would have allowed us to make a better graph that shows a better relation of the general
relationship between number of bands and the amount of stretch in each band. With our current
data, when we extrapolate our graph, it shows very unrealistic/impossible results with lower
numbers of rubber bands.