Archimedes Law Research Articles

Archimedes law simulation for physics instructional media

Students find physics difficult, because they have to contend with different representations such as experiments, formulas and calculations, graphs, and conceptual explanation at the same time. As far as we know that physics experiments which conducted in well-equipped laboratories, improve student’s science process skills. It is hard to imagine learning to do science, or learning about science, without doing laboratory or fieldwork. But many schools in various part of the world have very poor or no laboratories, so the teachers have to use their own equipment and replace the students experimental work with simple demonstration experiments. The purpose of this study was to create physics learning media for Archimedes law using simulation to cover the lack of the availability of laboratories and physics practicum tools. Rapid prototyping lifecycle model was used as a design of study. CSUQ is used to test usability of the simulation. To test the functional aspect, this study used black box testing the result of questionnaire was 88.4% with very decent criteria. Based on the development steps and test results, it can be concluded that developing a simulation requires full collaboration between IT experts and physics.

Characteristic of Synthetic Coral Scaffold for Cell Environment

Introduction. Synthetic coral scaffold is fabricated the mimicking of natural sea coral as a scaffold for bone regeneration [1]. Scaffold is performing functions as a micro environment for cells attachment, growth, proliferates, differentiates until it can form new bone tissue. The proper design is needed to produce the scaffold [2]. The purpose of this study was to investigate the characteristics of synthetic coral scaffold for micro environment of cells by observing cell attachment, hydrophobicity, and scaffold porosity. Experimental. Synthetic coral scaffold consists of bovine gelatin dan CaCO3 by weight, the concentration that be used are 4:6. Sodium citrate is used as dispersant. Thick film like scaffold was prepared for this study [1,3]. Vero cell line was used for observing cell attachment to investigate the biocompatibility the scaffold. The hydrophobicity was observed with distilled water droplets dripped on the scaffold surface, be analyzed in a photograph taken by the camera and then measured the angle. Percentage of porosity was measured using Archimedes law in absolute ethanol. Results and Discussion. Vero cells attached successfully into scaffold. Cell viability percentage is 91,77 % from the absorbance value of the MTT assay. It presented that the scaffold has biocompatibility character. However, the percentage of porosity is 55,85%, so the scaffold has enough porosity for cell attachment. Porosity serves for the diffusion of nutrients, gases and removes the residual metabolism resulting from cell activity that has grown on scaffold. The good porosity value of the scaffold is 50-90%. The higher the porosity value the better the scaffold. Hydrophobicity scaffold appears from the contact angle of 81.4°, the cohesion is greater than the adhesion. This shows the greater synthetic coral scaffold hydrophobicity, which is affected by surface roughness from scaffold porosity. The greater hydrophobicity will also prolong the degradation of the scaffold, thereby enabling cells to proliferate, differentiate and produce bone matrix. Conclusions. Synthetic coral scaffold provides the micro environment for cell, high hydrophobicity allows longer degradation for proliferation and differentiation of bone cells, and porosity that allows cells to be inserted within the scaffold.

Students’ responds in using Beboo to learn Static Fluid concept

Beboo is a bilingual (English-Indonesia) interactive e-Book with virtual laboratory feature. Beboo has been developed in Static Fluids Concept for teaching package. It contains many contents like pressure, hydrostatic pressure, Pascal law, Archimedes law, capillarity, viscosity and surface tension. In experiment process, this e-Book supports the virtual laboratory, U-Pipe system. Beboo is designed to succeed the international program in senior high school level in Indonesia as the learning source. Twenty-four students have been used Beboo in the classroom. This particular research explored the student responds to this e-Book. Students have been tried the U-pipe virtual laboratory and determined the density of the fluid from that activity. As the result, students found Beboo to be a positive learning experience with all the content, language, media and learning aspects state in a good and very good category. It means the student can use and simulate the experiment to determine the density of the fluid. However, students have a problem in language aspect. The data showed this aspect state in lowest respond percentage (73%) than others.

Metode Pengembangan Media Pembelajaran Model True or False Physics Fun Game Card

Abstract - Physics learning is still considered as learning that is less attractive to some students. Students’ lack of learning interest in physics learning makes their achievement low. The purpose of this study was to develop a learning media of True or False Physics Fun Game Card, so as to make the students interested in learning physics which could increase students' interest and learning achievement. The kind of the card game "True or False Physics Fun Game Card" was developed from a 41 card game which was modified as needed. In True or False Physics Fun Game Card, there were 50 true and false statements. Moreover, there were also points of 10-25 based on the level of difficulty of the statements. The statements made based on the Hydrostatic Law, the Relating Vessel, and the Archimedes Law. The True or False Physics Fun Game Card was developed by using the ADDIE development model which consists of 5 development steps, such as analyzing, designing, development, implementation, and evaluation. This study was tested on 12 samples of the Physics students of Universitas Kristen Satya Wacana. The data obtained were processed qualitatively and quantitatively. Based on the results of this study, it was found that 93.75% of students responded positively toward the learning media “True or False Physics Fun Game Card” and the average value of the students' post-test results was 72.67. The 10 samples from a total of 12 test samples obtained the post-test result; 65, so as the percentage of the successful comprehension sample was 83.33%. This study contributed to increasing kinds of learning media and improving students' learning achievement, especially in physics learning.

PENGARUH TEKNIK PROBING-PROMPTING TERHADAP KEMAMPUAN MEMECAHKAN MASALAH PADA PEMBELAJARAN FISIKA SISWA KELAS X SMA

This research is motivated student of low ability in problem solving because students simply fixated on theory so difficult applied to real life. In learning physics concerning materials that occur naturally in the environment is not just a theory but delivered only link between the material being taught and the students in real-world situations. Therefore need a solution in the form of innovation to improve students problem-solving skills. This study aims to determine the effect of techniques probing-prompting for problem-solving skills in learning physics class X SMA N 1 Juwana academic year 2014/2015 on the subject the Law of Archimedes. This study uses a pre-experimental research design with pretest-posttest form only control group design. Samples were taken by purposive sampling that is in class X Mia 2 as a single experimental class. Analysis of the initial data including normality test, while the final data analysis including normality test, hypothesis testing, gain test, and test indicators of problem-solving skills. After analysis it was found that the experimental class are normally distributed. The results of calculations based on the t test analysis obtained by value tcount > t table that is 15.722 > 2.68 with a significance level of 5% with db = 36. Because tcount > t table then H0 is rejected and Ha is accept. From the results of t test analysis can be concluded that there are significant administration-prompting probing techniques for problem-solving skills in learning physics class X Semester 2 SMA N 1 Juwana on the subject of the law of Archimedes.

The Alternative Procedures of Fiber Volume Ratio Determination of Long-Fiber Carbon - Epoxy Composites

The need to determine actual fiber volume ratio of the real composite part manufactured in the semi-closed mold led to application of the alternative procedures than the widely used Burn-off method. The low cost one, which is required preferably by any manufacturer, is based on Archimedes law (AL) and the most accurate determination of volume of displaced water. The more complex method which is based on the reverse engineering approach where the 3D scan technique is used to determine the volume of the part. Both are nondestructive methods. And finally the last method mentioned in this study is a sophisticated optical visualization technique and Figure post-processing by mathematical software (it was used NIS Elements and Wolfram Mathematica). Figures for mathematical post-processing were taken using light optical microscope (LOM) and scanning electron microscope (SEM). While better contrast between matrix and fibers is achieved in case of composites filled by transparent fibers, SEM figures provide better image contrast for non-transparent fibers.The AL and 3D measurement methods are very precise and suitable for orientative control during production, but they give only an average values of the fiber volume ratio in whole product. The mathematical post-processing of image is suitable for laboratory designing of composite part. It is destructive investigation method and image thresholding is time consuming, but on the other hand image processing gives the resultant fiber volume ratio in a particular cross section of the part. That makes the technique a good tool to find the weakest place of the part in meaning of the mechanical properties.

Fabrication and Morphological Characterization of Polyurethane Foam Reinforced with TiO2 Nanoparticles

ABSTRACTPolyurethane foams with various isocyanate/polyol ratios, reinforced with various amounts of nanosized TiO2, were prepared and their morphological properties were investigated. The nanoparticles were dispersed into the polyol component by stirring and then heating during ultrasonication to avoid particle agglomeration. Both scanning electron and transmission optical microscopes were used to evaluate the role of the nanosized TiO2 on the porous structure of the polyurethane foams. Cell size distributions were obtained by measuring the average cell diameters of the cells in the micrographs. To have a better assessment of nanoparticle effects on the foam morphology sample densities were measured using Archimedes law. For better understanding of microstructure evolution the heat release rate during the foaming process was characterized. The results showed that the values of cell size, cell density, apparent density and heat release rate depended on the ratio of isocyanate/polyol as well as TiO2 content.

Profile of Students’ Mental Model Change on Law Concepts Archimedes as Impact of Multi-Representation Approach

This paper outlined the results of an experimental study on the effects of multi-representation approach in learning Archimedes Law on students’ mental model improvement. The multi-representation techniques implemented in the study were verbal, pictorial, mathematical, and graphical representations. Students’ mental model was classified into three levels, i.e. scientific, synthetic, and initial levels, based on the students’ level of understanding. The present study employed the pre-experimental methodology, using one group pretest-posttest design. The subject of the study was 32 eleventh grade students in a Public Senior High School in Riau Province. The research instrument included model mental test on hydrostatic pressure concept, in the form of essay test judged by experts. The findings showed that there was positive change in students’ mental model, indicating that multi-representation approach was effective to improve students’ mental model.

Pembelajaran Kooperatif dengan Media Virtual untuk Peningkatan Penguasaan Konsep Fluida Statis Siswa

Physics is contain a lot of abstract concept.this thing arise student’s difficulty in learning physics individually. This difficulty can be solved by educators with using the method of cooperative learning on teaching their pupil. Beside of that, on teaching abstract concept can be helped by using virtual media. Because of that, this research is aim to test the effect of cooperative learning with virtual media toward the student’s conceptual understanding in physics on static fluid matter. Pre-test and post-test was gived to experiment and control class. The instrument of the test is conceptual test which consist of six cognitive aspect. The result show that the cooperative learning with virtual media increased student’s conceptual understanding in static fluid and significantly increased at sub-matter Archimedes law and fluid pressure. This result also showed the increase of student’s cognitive abilty on experiment class, but one of cognitive aspect C6 (create), control class more better than experiment class.

Characterization of Inkjet Printed Electrodes with Improved Porosity

Since a considerable amount of polymer electrolyte fuel cell (PEFC) stack cost is associated with platinum (Pt) that serves as a catalyst, reduction of Pt loading in the catalyst layers (CLs) without affecting the performance is a major research goal of the fuel cell industry. One of the essential factors affecting the Pt loading in the CLs is the fabrication technique used. Inkjet printing (IJP) is one such technique that can produce CLs with low Pt loading and a high Pt utilization [1-3]. However, a drawback for the IJP CLs, was found to be a reduction in porosity at higher Pt loadings, which corresponds to the increased number of deposited layers [2]. This was a major limiting factor affecting the performance of IJP electrodes, when comparing to conventionally fabricated electrodes [2]. In this work, a modified catalyst ink formulation is used, resulting in CLs that have a higher porosity compared to previous layers. Further, a methodology to determine the CL porosity, based on Archimedes law, is reported. The catalyst ink consisted of 50 wt. % Pt/C catalyst dispersed in a mixture of Isopropanol, 5 wt. % ionomer solution and a diol solvent to increase the ink viscosity. The improvement in porosity was achieved using a higher volatility solvent in the ink. A Fujifilm Dimatix inkjet printer was used for the CL fabrication process. Details regarding the fabrication process can be found in our earlier work [2]. The Pt loading in the CLs was determined by X-ray fluorescence analyzer (Themo Scientific Niton XL3t). The target Pt loading was 0.15 mg/cm2, corresponding to approximately 16 printed layers. For comparison, electrodes using the previous ink recipe were also fabricated and analyzed [2]. The CLs were imaged using a laser scanning microscope to estimate the crack density and a scanning electron microscope (SEM) to determine the CL thickness. In-situ characterization of the electrodes was done in a 40 cm2 cell to compare the performance at different conditions, electrochemical active area and oxygen transport resistance using AFCC testing protocols. For determination of CL porosity, a commercially available density determination kit (Sartorius mechatronics) was modified in-house and used in tandem with a Python based GUI to monitor the sample weight. The setup resembled the one reported by Rashapov et al. [4]. A PTFE substrate was used for the CLs when measuring porosity. Weight of the sample (CL + substrate) was taken in air, n-octane and deionized water. The total pore volume is obtained with the hypothesis that octane intrudes all the pores in the sample, thus reflecting its solid volume fraction, whereas water does not intrude any pores owing to its high surface tension, reflecting the CL bulk volume. To reduce the measurement error, an average of at least three weight readings was taken in each medium. The overall porosity of the IJP CL using the modified recipe was found to be 69.5±2.3 % compared to 51.3±2.2 % using the previous ink recipe, indicating a substantial improvement in the porosity [2]. This is reflected in the preliminary in-situ testing where a gain between 20 – 50 mV is achieved at different operating conditions compared to previous IJP electrodes. CLs using the modified ink recipe showed a power density of 1 W/cm2 at 0.6 V at normal operating conditions (680C, 70% RH), indicating that inkjet printing appears to be a feasible technique for electrode fabrication. Further testing of the CLs is underway.

Preparation of SiC Porous Ceramic for Application in Filter Plate Supports

In order to improve the efficiency of solid-liquid separation, dewatering and filtration, as well as to reduce the loss of concentrate and production costs, silicon carbide porous ceramic filter plate with high porosity and high bending strength was prepared by using the particles close packing method adding proper amount of adhesives and sintering additives at 1450 oC. The porosity of the fired samples was evaluated by Archimedes law. The morphology and properties of the samples were characterized. Effects of SiC grains gradation, pore formers content, molding pressure and soaking time on the bending strength and porosity of ceramic filter plate was studied. SiC porous ceramic composition was prepared by mixing 90wt% and 10wt% SiC powders with D50 of 200.7 μm and 312.6 μm, respectively, 4% walnut powder as pore former and 5% Kaolin clay as binder. The sample was pressured at 8 MPa and fired at 1450 oC for 30 min, and endowed with 6-8 μm of the average pore diameter, 41% of the porosity and 11 MPa of the bending strength, respectively, which is especially not easy to plug hole. The obtained results can be applied in ceramic filter core parts for heavy metal concentration.

Determination of the Temperature Coefficient of Volume Expansion Heat - Transfer Fluids by Using Refractometer

The aim of the submitted work is in the comparison of the two methods used for determination of the temperature coefficient of volume expansion (β) of heat transfer fluids. Temperature coefficient of volume expansion is one of the fundamental thermo-physical parameters monitored in the heat transfer fluids for solar collectors. A first method is based on commonly used Archimedes law principle and second deals with the determination via Abbe refractometer. Measurement of β using an Abbe refractometer is not very common, but in a practical way simpler and quicker than the methods based on the Archimedes principle. The identified thermal volume expansion coefficient under two different methods was compared and also has been found the relation between refractive index and β of the heat-transfer fluids measured by Abbe refractometer.

Effects of Pore Former on Properties of Alumina Porous Ceramic for Application in Micro-Filtration Membrane Supports

Due to its excellent chemical stability, high temperature resistance and mechanical properties, alumina porous ceramic was the first choice of the production of microfiltration membrane support body material. In this paper, alumina porous ceramic was prepared by alumina as main materials and adding proper amount of adhesives and sintering additives. Effects of the kinds and addition of pore formers, such as starch, graphite and carbon-black, on properties of alumina porous ceramic was studied. The porosity of the fired samples was evaluated by Archimedes law. The fired samples were characterized by scanning electron microscopy (SEM), compressive strength and mercury porosimeter measurements. Alumina porous ceramic composition was prepared by mixing 100% alumina with different particle size and 8 % graphite pore former. The sample was pressured at 10 MPa and fired at 1650 °C for 2 h, and endowed with 6-8 μm of the average pore diameter, 37.65 % of the porosity and 40.33 MPa of the compressive strength, respectively. The influence law of the kinds and addition of graphite pore former on the performance of alumina porous ceramic was studied for application in micro-filtration mmembrane supports.

PROTOTYPE POMPA APUNG

ABSTRACT Floating pump is a water pump than can flat and adapt to the level of water surface. This water pump is solution of the problem happens because of the significant increase an decrease of the level of water. If this 125 watt water pump installed on the ground surface it is unable to suck water because the well water depth passes the maximum height of the water pump’s ability to suck water. If the water pump installed by hanging over the well, there is possibility of being soaked when the level of water surface increased. Working principal of the floating pump is based on the archimedes law, where every object that immerses in a liquid (water) will get a force to the top which valve is as big as the liquid removed by the object. Floater loaded by air install under the pump’s plate and support the weight of the floating pump system so that the system can float. The floating pump can be used and relatively stable of the shake of the machine pump and of the increase and decrease of the water level because it follows the increase and decrease velocity of the well water level. Flexible water pipe gives flexibility to the pump system to go up and down, following the water level. Height of the suction is not very high less than 20 cm and it is always constant because the pump system floating on the water surface. If it is compared by the maximum suction, 9 meters, it doesn’t affect the suction debit. Along with the level decrease of the pump system following the degradation of the well water level when the pump operated, there is a decrease in the debit because of the height increase of pushed pipe. Key words: floating pump, floater, water.

Study on Effect of Resonance on the Motion of Floating Body

This paper aims to study the impact of resonance on floating body motion. According to Archimedes law, Newton's second law of motion and general form of simple harmonic oscillations, nature frequency is gotten in the numerical calculation. Then, the result is validated using four bodies with different weights in numerical calculation and finite element simulation.

Archimedes law under bifurcations of solution and partial averaging of phenomenological variables

A model of the convective flow of viscous fluid is proposed with regard to possible finite “fluctuations” of thermophysical characteristics in a neighborhood of branch points. A method for the analysis of the influence of averaging on the values of phenomenological variables for the secondary flow and exact bounds on these values are calculated.

O paradoxo hidrostático de Galileu e a lei de Arquimedes

Traditional pedagogy has underestimated the presence of some mysteries and paradoxes in Physics teaching. Naive inductivistic approaches in Science education have also contributed to the fact that some important theoretical assumptions are usually discarded. Historical, conceptual and experimental analysis of Physics development can positively contribute to restore the importance of such assumptions in physics teaching. In this article we analyze the so called Galilean Hydrostatic Paradox, a mystery directly connected to Archimedes Law of Hydrostatics. Experimental analysis of this theme is presented in a well-documented photographic way and conclusions are drawn as an example to show the extent to which a competent analysis of such hidden assumptions can subvert traditional and orthodox education in Physics.

Absence of the fifth force problem in a model with spontaneously broken dilatation symmetry

A scale invariant model containing dilaton ϕ and dust (as a model of matter) is studied where the shift symmetry ϕ→ϕ+const. is spontaneously broken at the classical level due to intrinsic features of the model. The dilaton to matter coupling “constant”f appears to be dependent of the matter density. In normal conditions, i.e. when the matter energy density is many orders of magnitude larger than the dilaton contribution to the dark energy density, f becomes less than the ratio of the “mass of the vacuum” in the volume occupied by the matter to the Planck mass. The model yields this kind of “Archimedes law” without any especial (intended for this) choice of the underlying action and without fine tuning of the parameters. The model not only explains why all attempts to discover a scalar force correction to Newtonian gravity were unsuccessful so far but also predicts that in the near future there is no chance to detect such corrections in the astronomical measurements as well as in the specially designed fifth force experiments on intermediate, short (like millimeter) and even ultrashort (a few nanometer) ranges. This prediction is alternative to predictions of other known models.

Publisher’s Note: Maxwell stress in Rindler space and the Archimedes Law [Phys. Rev. D74, 025002 (2006)

Publisher’s Note: Maxwell stress in Rindler space and the Archimedes Law [Phys. Rev. D<b>74</b>, 025002 (2006)

Maxwell stress in Rindler space and the Archimedes Law

We construct a theory of Maxwell stresses in Rindler space, presenting both a noncovariant and a covariant formulation. The theory shows how the Maxwell stresses are modified by a nonvanishing acceleration of gravity and that the Maxwell stresses of an electromagnetic field produce a volume stress force which vanishes in an inertial frame. In the noncovariant formulation we deduce the Maxwellian force due to the bending of the field lines by the acceleration of gravity. In the covariant formulation we show that Archimedes' law is valid for stationary electromagnetic fields in Rindler space: The Maxwellian surface forces acting from the outside field upon a closed surface produce a buoyancy equal to the weight of the electromagnetic field enclosed by the surface. Generally the mechanism is different from that in a fluid in which the buoyancy is due to a pressure which increases with depth. In a vertical electrical field the buoyancy is due to a tension that increases with height, but in a horizontal field it is due to a Maxwellian pressure which increases with the depth.