Result
The following result was reached when investigating the shot length on different stretching lengths:
These values are then inserted in a graph, which looks like following:
On the x-axis we have the stretch of the rubber band in meters, and on the y-axis we have the shot length in meters. The different points represent the length of the shots on different stretching values. The lines are drawn to best fit.
Conclusion
We see a clear result, and it does indeed follow our hypothesis. The more the rubber band is stretched, the longer the shot length becomes. As kinetic energy is required for anything to move, we can draw the conclusion that that kinetic energy must have come from somewhere, and in this case it was the potential elastic energy in the rubber band, which was stored in it when stretched.
However, another interesting result was reached. As we see in the diagram, the lines drawn to best fit are not linear, but shaped as curves. This implies that the increase in shot length is not correlating to the increase in stretching. As the table and the diagram show, the flight in meters per stretched meter decreases the more you stretch the rubber band.
We also see that the curves cross each other. Rubber 2, which had a shorter flying distance, would when stretched only 0.004 m, have a greater range than rubber 1 with the same stretching. This low value of stretching of course is quite hard to measure as you probably would not have been able to release the rubber band at all. Perhaps if you would have used rubber bands in a larger scale and with some differentiating property, a difference would have been possible to actually measure. However, to draw any conclusion like this from the graph probably should not be done. Our measuring points are nowhere close to the actual crossing of the lines, but at least a hint about what might happen is given, even though we can not draw any certain conclusions.
Evaluation
The result seems to be trustworthy, as the number of trials gave a reasonable mean value. More stretching lengths of course could have been tried, but probably the result is quite reliable.
The hypothesis proved to be correct, as the result followed the hypothesis. However, we gained more information than we were searching for, and perhaps we could have tried not to have such a narrow aim with the experiment, but try to get a broader perspective. To have a wider aim would have given us more depth in the experiment.
The rubber bands used were of different size and thickness and had different stiffness. If we could have narrowed it down to only one different variable, it would have been possible to make a more true statement, and also to investigate how that specific variable affected the shot length. With the current rubber bands, which have such different properties, it was fairly futile to use two rubber bands, as we not were able to draw any certain conclusions. The two rubber bands simply were different in too many ways to enable the drawing of any certain conclusions. We can not be sure whether it was the circumference, the thickness or the stiffness that projected the difference in shot length.
Our measuring points should have been adjusted to give the same amount of stretching on both rubber bands. This would have given the same stretching, but hopefully and probably still a different shot length.
The actual shooting part probably could have been worked out in a better way. As it was now, you had to poke the rubber band above the rear flag so it would be released. This worked relatively well, but the rubber band sometimes did hit your finger and its range hence decreased. The rubber band also had a tendency to hit the second flag on its way downwards and forward. These two problems were hard to avoid with the setup we used, so a better setup would have been preferred before the used one.
To further improve the experiment it could have been performed in vacuum. This would have removed air resistance. However, the experiment probably would not have been affected that much, but it would have been improved, at least to some extent.
We did forget to measure the height above the ground of the rubber band when positioned on the flags. However, as the height remained the same throughout the experiment, it did not affect the experiment. If we would want to repeat the experiment with other rubber bands and compare it with existing results, the height would though have been good to have, as the height also affects the length of the shots. We also did not control the temperature of the surroundings. The temperature of course affects the properties of the rubber band.
The landing point of the rubber band could, and should, have been better controlled. Our result is only correct to the nearest five centimeters, and that is not very exact. Eye measuring was used this time, but if we would have performed the experiment on some kind of sand surface, the rubber band would have left a clearly visible trace, and we would have known the length of the shot to the nearest centimeter, if not to the nearest millimeter.
If all these improvements would have been made, the experiment would have generated both a more secure conclusion, but also a wider one. Now the second rubber band was just a waste of time, as it did not generate any results which could be used in the conclusion. It could instead have helped to improve the experiment.
