Experimental evaluation of the drag coefficient of water rockets by a simple free-fall test

Perotti, Raúl Barrio; Marigorta, Eduardo Blanco; Argüelles-Díaz, K; Oro, Jesús Manuel Fernández

doi:10.1088/0143-0807/30/5/012

Cited by 16 publications

(13 citation statements)

References 14 publications

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“…The negative sign at Fw and F show the direction of vector where gravitational acceleration worked to Fw and F have direction to the center of the earth, so the vector sign is negative. Fu represents the number of Bouyance's force and FD is the air drag force with direction is opposite of the direction of object motion, like friction, so it is positive [12] Thus, the equation (3) may express as Equation 4.…”

Section: Newton's Mechanicsmentioning

confidence: 99%

Do It Yourself: Air Drag Force Experiment Using Paper and Scraper Sheet

Zakwandi

Ariswan

Nurfalah

et al. 2021

J. Ilmu. Pend. Fisika

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Free fall motion in air medium is only influenced by gravitation acceleration. However, there are several variables that caused the observations to be different with the concept. Variables, such as air drag and terminal velocity, are often teachers not presented in detail, causing misconceptions. This study aims to develop a simple experiment on free fall motion by identifying air drag and terminal velocity. The data in this study is the video of free fall motion of paper and scraper analyzed using Tracker video analyze. From the video analyzed, information is obtained in the form of time (t), track (l, θ), and velocity (v) of the object. This study shows that the air drag force increase unto the terminal velocity. The calculation of the drag coefficient giving the number of the paper 2,16 and the scraper 2,10. According to data analyzed, the air drag force is affected by the mass (m), area (A), and the air drag force (F<sub>D</sub>) with the linear correlation until it reaches the terminal velocity. The result of this study may use as references of free fall motion experiment with other objects and analyze.

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Section: Newton's Mechanicsmentioning

confidence: 99%

Do It Yourself: Air Drag Force Experiment Using Paper and Scraper Sheet

Zakwandi

Ariswan

Nurfalah

et al. 2021

J. Ilmu. Pend. Fisika

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“…In addition to the geometric parameters and the densities listed in Table 2, the fluid drag coefficients for all segments need to be prescribed. According to the body segment shape and the Reynolds number during swimming (4 × 10 6 ) and by referring [30,44,45], the fluid drag coefficients are set as C t = 0.036, C n = 1.3, and C a = 0.85. The kinematic data of human swimming also come from [30].…”

Section: Swimming Performance Evaluationmentioning

confidence: 99%

Effects of Currents on Human Freestyle and Breaststroke Swimming Analyzed by a Rigid-Body Dynamic Model

Bao

Fang

2021

Machines

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Swimming is a kind of complex locomotion that involves the interaction between the human body and the water. Here, to examine the effects of currents on the performance of freestyle and breaststroke swimming, a multi-body Newton-Euler dynamic model of human swimming is developed. The model consists of 18 rigid segments, whose shapes and geometries are determined based on the measured data from 3D scanning, and the fluid drags in consideration of the current are modeled. By establishing the interrelations between the fluid moments and the swimming kinematics, the underlying mechanism that triggers the turning of the human body is uncovered. Through systematic parametric analyses, the effects of currents on swimming performance (including the human body orientation, swimming direction, swimming speed, and propulsive efficiency) are elucidated. It reveals that the current would turn the human body counterclockwise in freestyle swimming, while clockwise in breaststroke swimming (which means that from the top view, the human trunk, i.e., the vector pointing from the bottom of feet to the top of the head, rotates counterclockwise or clockwise). Moreover, for both strokes, there exists a critical current condition, beyond which, the absolute swimming direction will be reversed. This work provides a wealth of fundamental insights into the swimming dynamics in the presence of currents, and the proposed modeling and analysis framework is promising to be used for analyzing the human swimming behavior in open water.

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“…Experimentos didáticos em que o tempoé medido dessa maneira já foram realizados anteriormente [1][2][3][4][5]. No presente trabalho nós descrevemos mais duas aplicações desta técnica.…”

Section: Introductionunclassified

O computador como cronômetro

Aguiar

Pereira

2012

Rev. Bras. Ensino Fís.

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Experimentos de mecânica frequentemente requerem medidas de intervalos de tempo da ordem de décimos ou centésimos de segundo, difíceis de realizar com cronômetros manuais. Neste trabalho nós apresentamos um método de efetuar tais medidas, utilizando um computador equipado com placa de som e microfone. A ideia básica é simples: como muitos sistemas mecânicos têm sua evolução temporal marcada pela emissão de sons, uma gravação de áudio pode fornecer medidas extremamente precisas dos intervalos de tempo de interesse, mesmo quando eles são muito pequenos. Descrevemos dois experimentos didáticos que utilizam gravações digitais para medir tempos. Em um deles determinamos a velocidade com que uma bola de futebol é chutada. No outro obtemos o tempo de queda livre de um corpo. Descrevemos também a implementação dos experimentos em escolas de ensino médio e apresentamos alguns resultados obtidos pelos estudantes.

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Experimental evaluation of the drag coefficient of water rockets by a simple free-fall test

Cited by 16 publications

References 14 publications

Do It Yourself: Air Drag Force Experiment Using Paper and Scraper Sheet

Do It Yourself: Air Drag Force Experiment Using Paper and Scraper Sheet

Effects of Currents on Human Freestyle and Breaststroke Swimming Analyzed by a Rigid-Body Dynamic Model

O computador como cronômetro

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