Force = Constant * Extension
So I predict that if I were to change the angle of firing to an angle more than 45o the rubber band will not goes as far as a rubber band which is fired at an angle less than 45o such as 30o. This is because if a projectile is fired at an angle which is more than 45o has to climb a steeper gradient. So by doing this it loses more engird going up in flight, so this energy will be changed in to potential energy quicker and it will fall at a smaller distance.
However, it does not mean that if I fire the rubber band at an angle such as 10o it will go further than a band fired at 30o. This is because 30 are closer to the optimum angle of firing which is 45o. I predict that the graphs for distance travelled against angle should look something like this.
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The equation for an elastic band being fired is this it changes twice form its original equation:
Potential Energy ------------> Kinetic + Heat Energy
Kinetic Energy ------------> Potential Energy
Potential Energy ------------> Kinetic Energy
The energy change is automatic as it reaches the maximum height and then all the kinetic energy changes into potential energy and then in a split second returns all back to kinetic energy.
Safety
Safety is an important aspect in every experiment, even if the experiment seems to be very harmless. And that is why we take this into consideration, no matter what. We will be using a rubber band, which could injure someone if it’s not used properly. And we will also be careful that the rubber bands do not get fired at people’s bodies, just in case, because we are not fully aware of the damage it could do to us. But other than that, there were not any bigger matters to be cautious of. But all laboratory rules were carried through correctly.
Diagram:
Method
- Set the Experiment up as the diagram shows above.
- Place the measuring tape at the end of the ruler attached to the stool, and pull the tape out until over 6 metres is in place.
- Pull the elastic and back 10 centimetres and release after 4 seconds of the band being at 10 centimetres.
Table of results:
Analysis:
This graph shown above gives the line of best fit for the average distance travelled by an elastic band, when fired at different angles, over the course of the experiment. The graph is a curve that slopes downwards and does not go through the origin. Because the line is not straight and does not pass through the origin, it means that the average distance travelled and angle of firing are not directly proportional.
However, there is a pattern on my graph, and this is, as the angle of firing increases, the average distance travelled decreases. The graph shows that the average distance travelled is in inversely proportional to the angle of firing. The gradient does change in my graph. It gets less steep as X-axis gets bigger.
From the line of best fit that has been added in, it can be seen that all of my points were very close to creating a perfectly smooth curve. This shows that my results are fairly reliable. My graph fits in with my prediction of the experiment graph.
Conclusion:
In conclusion I believe that my hypothesis was correct, this is because in between the range of 20 and 35 degrees the average distance travelled by the elastic band was much further than any others. This is because there is less of an energy loss and that the elastic band does not have to climb a steeper gradient. The average distance travelled range is from 250.4 cm to 450.6 cm, but it does not increase as the angle of firing increases. The average peaks at 20 degrees, which is almost half the optimum angle and then starts to decrease slowly, all the way backs to 60 degrees.
So if I was to refer back to my energy change general formulas:
Potential Energy ------------> Kinetic + Heat Energy
Kinetic Energy ------------> Potential Energy
Potential Energy ------------> Kinetic Energy
The energy change is automatic as it reaches the maximum height and then all the kinetic energy changes into potential energy and then in a split second returns all back to kinetic energy.
If I was now to make a statement about the energy change at 20 degrees compared to the energy change at 50 degrees, I could say that there is a greater energy loss at 50 degrees than at 20 degrees. This is because the rubber band on average travelled further at 20 degrees to 50 degrees, this is due to the fact that energy is lost and converted into other forms.
As the gradient and flight of the rubber band at 20 degrees is smaller than at 50 degrees means that there is less energy lost to air resistance. And at 50 degrees the flight path of the rubber band is much steeper and therefore more energy is lost due to air resistance. You can see this in the diagram above.
Evaluation:
I followed the plan correctly, and believe we gained accurate and sufficient enough results to conclude the experiment, and to prove our hypothesis. My final results were very reliable, due to the precautions I took to make this a fair test.
To make this experiment better, I believe that we could have used a pin to hold the elastic band back on the ruler to that the pull back was exactly 10 centimetres each time. As I only pulled back to 10 centimetres which could have been in the range of 9.5 to 10.5 centimetres. Also if I could use the same force on the pull back each time would have made my experiment even better. But as I have already said I believe my experiment was carried out correctly and the data gathered was sufficient enough to agree with my hypothesis.
Repeating the same tasks many other times would not have been very useful, since we had already done the result 5 times, and ALL the results were reliable.
Even though we did not use these experimental plans, we still got results, which were correct, according to my hypothesis, and backed, up my predictions.
But overall, given the apparatus that we got to carry out the test, I think this experiment turned out to be very successful, and I’m very please with my results.
