The physics of perfect rockets
01 Mar 1995-American Journal of Physics (American Association of Physics Teachers)-Vol. 63, Iss: 3, pp 229-232
TL;DR: The most efficient way to operate a rocket is to increase its exhaust velocity as it accelerates as discussed by the authors, when this increase is done properly, the final kinetic energy of the rocket is maximized.
Abstract: The most efficient way to operate a rocket is to increase its exhaust velocity as it accelerates. When this increase is done properly, the final kinetic energy of the rocket is maximized. It is shown that the resulting ‘‘perfect rocket’’ is far simpler to analyze than the traditional constant‐thrust rocket and provides an excellent application of the material taught in all first semester noncalculus physics courses.
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01 Dec 2010
TL;DR: Details are provided about implementation and evaluation of one PBL project and how difficulties in evaluation of the linked-class PBL experiences are being addressed.
Abstract: Problem-Based Learning (PBL) is a problem-centered teaching method with exciting potential in engineering education for motivating and enhancing student learning. Implementation of PBL in engineering education has the potential to bridge the gap between theory and practice. Two common problems are encountered when attempting to integrate PBL into the undergraduate engineering classroom: 1) the large time requirement to complete a significant, useful problem and 2) the ability to determine its impact on students. Engineering, mathematics, and science professors at West Texas A&M University (WTAMU) have overcome the large time commitment associated with implementation of PBL in a single course by integrating small components of the larger project into each of their classes and then linking these components with a culminating experience for all the classes. Most of the engineering students were concurrently enrolled in the engineering, mathematics, and science classes and were therefore participating in all activities related to the project. This linked-class PBL experience addressed course concepts, reinforced connections among the courses, and provided real-world applications for the students. Students viewed the experience as beneficial, increasing their understanding of content and applications in each discipline. This paper provides details about implementation and evaluation of one PBL project and how difficulties in evaluation of the linked-class PBL experiences are being addressed.
24 citations
Cites background from "The physics of perfect rockets"
...81 rocket motion has been used extensively in the past to motivate students to learn physics [7-11]....
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TL;DR: In this article, the authors presented a numerical solution for the height of the rocket, as well as several analytic approximations, and five out of six lab groups predicted the maximum height of a water-propelled, air-pumped, water-powered rocket within experimental error.
Abstract: The air-pumped, water-propelled rocket is a common child’s toy, yet forms a reasonably complicated system when carefully analyzed. A lab based on this system was included as the final laboratory project in the honors version of General Physics I at the USAF Academy. The numerical solution for the height of the rocket is presented, as well as several analytic approximations. Five out of six lab groups predicted the maximum height of the rocket within experimental error.
20 citations
TL;DR: The water rocket as mentioned in this paper is a popular toy that is often used in first year physics courses to illustrate Newton's laws of motion and rocket propulsion, and is made of a soda bottle, a bicycle pump, a rubber stopper, and some piping.
Abstract: The water rocket 1 is a popular toy that is often used in first year physics courses to illustrate Newton’s laws of motion and rocket propulsion. In its simplest version, a water rocket is made of a soda bottle, a bicycle pump, a rubber stopper, and some piping see Fig. 1. The bottle is half-filled with water, turned upside-down, and air is pushed inside the bottle via a flexible pipe that runs through the stopper. When the pressure builds up, the stopper eventually pops out of the neck. The water is then ejected and the rocket takes off. Witnesses of the launch of a water rocket cannot but be amazed that such a simple device can reach a height of tens of meters in a fraction of a second. The popularity of water rockets extends beyond physics classrooms, with many existing associations and competitions organized worldwide. 1 The more than 5000 videos posted on YouTube with the words “water rocket” in their title testify to their popularity. Some of these videos involve elaborate technical developments such as multistage water rockets, nozzles that adapt to the pressure, the replacement of water by foam or flour, underwater rocket launches, and even a water-propelled human flight. The public’s passionate explorations with water rockets contrast with the small number of articles devoted to their analysis. I found only two papers 2,3 that treat the simplest possible rocket, similar to
18 citations
01 Jan 2007
TL;DR: Problem Based Learning (PBL) as discussed by the authors is a teaching method in which students learn through solving a problem, and it has been used to address the problem of lack of motivation in engineering education.
Abstract: Educators and employers share a common goal of “educating/employing people who are highly motivated and who give 100% effort to their work”. The main reason that this goal is not realised is because the people being taught/employed lack motivation. On the education side a lot of what is taught is not applied so the students cannot see the benefit of this learning. On the employment side the workers are not able to apply what they have spent their undergraduate time learning. What is missing? The link between the students’ learning and industry needs. Problem based learning (PBL) seeks to addresses this problem. PBL is a teaching method in which students learn through solving a problem. This paper reports on how PBL addresses engineering education.
8 citations
TL;DR: In this paper, a detailed theoretical analysis of the physics of water rockets is presented, which concludes with the proposal of a physical model, which can be used to investigate the temporal evolution of some significant variables during propulsion and flight of the rocket.
Abstract: A simple rocket can be made using a plastic bottle filled with a volume of water and pressurized air. When opened, the air pressure pushes the water out of the bottle. This causes an increase in the bottle momentum so that it can be propelled to fairly long distances or heights. Water rockets are widely used as an educational activity, and several mathematical models have been proposed to investigate and predict their physics. However, the real equations that describe the physics of the rockets are so complicated that certain assumptions are usually made to obtain models that are easier to use. These models provide relatively good predictions but fail in describing the complex physics of the flow. This paper presents a detailed theoretical analysis of the physics of water rockets that concludes with the proposal of a physical model. The validity of the model is checked by a series of field tests. The tests showed maximum differences with predictions of about 6%. The proposed model is finally used to investigate the temporal evolution of some significant variables during the propulsion and flight of the rocket. The experience and procedure described in this paper can be proposed to graduate students and also at undergraduate level if certain simplifications are assumed in the general equations.
5 citations