Louis Buchholtz

Bio: Louis Buchholtz is an academic researcher. The author has contributed to research in topics: Bubble & Normal mode. The author has an hindex of 2, co-authored 3 publications receiving 33 citations.

Analysis of the vacuum cannon

Abstract: We develop a model for the velocity of a projectile in a vacuum cannon. The theoretical maximum velocity is independent of the vacuum cannon diameter and projectile mass and is significantly lower than the speed of sound. Experimental measurements support the theory as an upper limit.

Internal ballistics of a pneumatic potato cannon

Abstract: Basic laws of thermodynamics and mechanics are used to analyse an air gun. Such devices are often employed in outdoor physics demonstrations to launch potatoes using compressed gas that is here assumed to expand reversibly and adiabatically. Reasonable agreement is found with reported muzzle speeds for such homebuilt cannons. The treatment is accessible to undergraduate students who have taken calculus-based introductory physics.

A more thorough analysis of water rockets: Moist adiabats, transient flows, and inertial forces in a soda bottle

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

Aim for the sky: Fostering a Constructionist Learning Environment for Teaching Maker Skills to Children in India

Abstract: The education system in schools in India at large focuses on the transmission of knowledge to students and sets the expectation to simply memorize and reproduce it on tests in the form it was originally taught to them. In order to lay the ground for teaching 21st-century skills, it is imperative to go beyond the confines of the textbook and lecture-based learning and to encourage applying the knowledge imparted in the classroom in creative contexts and to solve problems. The paper discusses the workshop conducted to teach maker skills in the context of STEM-based learning to eighth graders in a semi-urban school in India. The students were taught to work with tools and the principles of design and the science required to create and launch water rockets. Pre-workshop and post-workshop surveys were conducted to measure for change in intrinsic motivation and general self-efficacy of the students who participated in the making activity. The results reveal a reported significant reduction in performance related tension and pressure after participating in such collaborative activities among other findings that are discussed in detail in the paper.

When backyard fun turns to trauma: risk assessment of blunt ballistic impact trauma due to potato cannons.

Abstract: Although potato cannons are an area of great interest among internet users, they are almost completely unknown in the medical community. These simple ballistic devices are made from plastic plumbing pipes and are powered with propellant gas from aerosol cans. By combustion of the gas–oxygen mixture, a high pressure is produced which propels the potato chunks through the barrel. It is the aim of this study to investigate the hazardous potential of these shooting devices. Test shots were performed using three illegally manufactured potato cannons that were confiscated by police authorities. Velocity, impulse, kinetic energy, and energy density were calculated. The risk of head and chest injuries was investigated by using Sturdivan's Blunt Criterion (BC), an energy based five parametric trauma model assessing the vulnerability to blunt weapons, projectile impacts, and behind-body-armor exposures. The probability of lethality due to blunt impact trauma to the chest was assessed using Sturdivan's lethality model. For potential head impacts, all test shots far exceeded the critical BC (head) value which corresponds to a 50% risk of skull fracture. The risk of injury with regard to chest impacts was similar. All but two test shots far exceeded the critical BC (chest) value corresponding to a 50% risk of sustaining a thoracic skeletal injury of Abbreviated Injury Scale 2 or 3. The probability of a lethal injury due to blunt chest impact was as high as 20%. To conclude, this work demonstrates that potato cannons should be considered dangerous weapons rather than as toys used by adventurous adolescents.

The Ping-Pong Cannon : A Closer Look

Abstract: This paper describes the use of laser pulse photography, optical timing, and pulsed Schlieren to look more closely at the dynamics of a popular lecture demonstration—the so-called “Ping-Pong cannon” or “vacuum bazooka.”1,2 These optical diagnostic techniques are applied to two types of cannons and lead to greater knowledge of the kinematics of the accelerating ball, along with some details of the exit mechanism and subsequent target interactions.