How is the Time in Air Impacted by the Amount
of Water?
Abbie Bruno, Allie Balzer, Riley McAdams
Table of
Contents: Background .:. Statement of Problem .:. Hypothesis .:. Method .:. Results .:.
Analysis .:. Conclusion .:. Bibliography .:.
Related Websites .:. Go Up
Background (top)
The history of rockets starts long before what we consider to be modern rockets actually existed. This is mainly because people like to make things fly and blow up, but they didn’t know how for a long time. The first documented experiments with “rockets” were in Greece around 400 B.C. A mathematician and a philosopher pushed a wooden pigeon around with steam, and that became the beginning of the path to discovering rockets. The first “modern” rockets were built around 1000 A.D. in China, where they discovered that “gunpowder tubes, [made of saltpeter, sulfur, and charcoal dust], could be launched by simply igniting the powder and releasing the tube”. This resulted in the accidental invention of fireworks. As well as fireworks, rockets were often used as a form of weaponry in wars, starting when the Chinese fought off the Mongols with them around 1230 A.D. It was said that they were able to devastate the ground around them “up to 2000 feet in all directions”. It is said that there are three founding fathers of modern day rocketry: Konstantin E. Tsiolkovsky, Robert Goddard, and Hermann Oberth. Robert Goddard seems to be the most significant of the three because he was the first man to achieve flight with a liquid-Fueled rocket on March 16, 1926. Despite his research getting tons of media, “Goddard died before seeing his work vindicated.” Because of this we have decided to take on the task of experimenting with water rockets for ourselves, in Goddard’s honor. The very first water rocket made was in 1930 by Professor Jean LeBot in France, though he used Champagne bottles instead. Water Rockets and NASA Rockets are quite alike as they both are structured almost exactly the same. They are mainly used for entertainment though some people do use water rockets to learn about forces and external forces that may affect the rocket. For example, Water Rockets are really good for teaching students about inertia and acceleration and many other things, “Two-Liter Pop Bottle Rockets may well be the GREATEST PHYSICAL SCIENCE TEACHING TOOL EVER CREATED!” Before the rocket launches, the energy inside is completely potential, so that when the rocket does launch, there will be an equal and opposite reaction propelling the water rocket up from the pressure that was built up in the rocket before the launch. As more water is put into the rocket, it will create higher amount of force to push down on. This will also bring about higher levels of pressure, and the length of time in the air will increase in a similar way.
Statement of problem (top)
The purpose of this investigation is to determine whether the amount of water in a water rocket will directly correlate to the time it is in the air.
Hypothesis (top)
We believe that as the amount of water increases, the range will as well, because there will be more propellant to lift the rocket into the air. The range is defined as the amount of time in the air, and the propellant is the water used to fill rockets.
Method (top)
In order to successfully carry out this lab, it is necessary to have an open field that does not have objects that will interfere with the length of time it takes for the rocket to reach the ground, as well as at least two or more people to record data and perform the experiment. The rocket launcher works only when there is one individual pumping the pressure while the other removes the string of the release pin to allow the rocket to launch. A third person is helpful when it comes to the timing of the rocket. To test a control, no water was added into the rocket, and from there, the amount increased in percentages of the whole rocket (25% each time--0.5 Liters and roughly 2 cups). The rocket, using O-rings to maximize the pressure, was secured in place by the release pin and then the bike pump was pumped ten times before an immediate release of the rocket. Following the landing of the rocket (which immediately stops the timing), the data should be recorded, then repeated for a total of five times per amount of water.
Results (top)
|
Amount of Water (%) |
Trial 1 (s) ±0.130 |
Trial 2 (s) ±0.130 |
Trial 3 (s) ±0.130 |
Trial 4 (s) ±0.130 |
Trial 5 (s) ±0.130 |
Average (s) ±0.130 |
Uncertainty ±(s) |
|
0% |
3.89 |
3.62 |
3.54 |
4.12 |
3.73 |
3.78 |
0.290 |
|
25% |
4.09 |
4.45 |
4.35 |
4.40 |
4.28 |
4.31 |
0.180 |
|
50% |
4.25 |
3.73 |
3.90 |
3.82 |
4.17 |
3.97 |
0.260 |
|
75% |
1.99 |
2.24 |
2.38 |
1.88 |
2.17 |
2.13 |
0.250 |
|
100% |
1.68 |
1.54 |
1.32 |
1.59 |
1.73 |
1.57 |
0.205 |
Analysis (top)
As we started with our trials we thought that the research would follow our hypothesis as planned but then we got to four cups of water and the data told a different story. There was a positive difference of 0.53 seconds in air between the control and the bottle 25% full, but then it went down by 0.34 seconds and continued to trend downward. In fact it jumped by almost a full two seconds down from 50% to 75% full. I feel that this data is suggesting that there is an optimal amount of water somewhere between 25% and 50% that will give a time in air even longer than 4.45 seconds, which was the longest one in air we collected.
Conclusion (top)
Conclusively, the max time occured when we filled the rocket 25%. The amount of time the rocket was in the air decreased from then on, which made our hypothesis incorrect. While we did everything we could to make the results accurate, errors were to be expected. One circumstance that affected the calculations were the weather; There was pouring down rain as well heavy blowing wind. The rocket fins were made out of fragile cardboard, so some of the fins got bent up. If we were to repeat the experiment we would make the rocket out of something more durable and in weather that wasn’t so windy. Human error was also a source of error, but human error is inevitable regardless of the precautions taken. The person doing the timing took a reaction time test and that is where we got the uncertainty of ± 0.13 seconds. We used the time in air for each amount of water to calculate the rest of the uncertainties. The formula to calculate the uncertainty was the max value minus the min value divided by two.
In conclusion, our hypothesis was incorrect in stating that as the amount of water increases, so will the range. Around 25% was the best volume for a 2 liter bottle. In the future, we would do more tests and minimize our error in order to maximize the most efficient results.
Hamilton, Calvin J. “A Brief History of Rocketry.” Solarnews.com,.
Howell, Elizabeth. “Rockets: A History.” Space.com, PURCH.
Mazza, David. “All About Water Rockets.” NASA, NASA.
“Flight of a Water Rocket.” NASA, NASA.
“Water Rocket History.” Water Rocket History, 5 Apr. 2003.
http://solarviews.com/eng/rocket.htm
- A history of rocketry which gives a lot of insight.
https://www.space.com/29295-rocket-history.html
-A history on actual rockets and how they were made and who made them.
https://spaceflightsystems.grc.nasa.gov/education/rocket/BottleRocket/about.htm
- Gives an explanation as to how water rockets work.
https://www.grc.nasa.gov/www/k-12/rocket/rktbflght.html
- Gives an explanation as to how rockets work compared to water rockets.
http://waterocket.explorer.free.fr/water_rocket__history.htm
- Gives a brief history lesson on water rockets.
https://youtu.be/R625vwA4jpQ?t=3m31s
– A way cooler version of what we did (in video form).