Kartika Hajar Kirana

Optimization of Rectilinear Motion Experiments using Tracker Application

Physics is one part of Natural Sciences which underlies the development of technology, so that the process of learning Physics should not only emphasize the mastery of the concept but also on aspects of the discovery as the scientist did. Therefore, experimental activities are considered very important in Physics learning. In the experimental activities, it is important to have appropriate tools and methods of measurement to obtain accurate findings. One of the experimental activities of physics which conducted in school is a uniformly acceleration rectilinear motion using a set of dynamics train experiment and Atwood experiment. The measurement methods of both experiments generally use conventional tools, i.e. ruler, stopwatch and ticker timer that are susceptible to interruptions and errors in the data acquisition process. One method of measuring and processing data that considered has more precision is to use the application tracker. In this research, a uniform rectilinear motion kinematics experiments have been done with two methods of measurement using conventional tools and compared with using the tracker by recording the movement of objects using high definition camera (HD) with 24 fps shooting speed. The results showed that the result using tracker to produce some acceleration data is more constant than the result using conventional methods. In addition, time-positions graphs (s = f (t)) are formed in the form of quadratic and time-velocity graphs (v = f (t)) are straight lines with a constant gradient corresponding to the rectilinear motion theory. Based on the results of the research, the use of tracker application in the experimental kinematics of rectilinear motion produces more accurate data so it can be used as an alternative to optimize the experiments of rectilinear motion.

Problem Solving-Based Experiment untuk Meningkatkan Keterampilan Penalaran Ilmiah Mahasiswa Fisika

As one of the foundations in the development of technology, physics must be supported by experimental activities that are able to develop a scientists skills, such as scientific reasoning skills. Experiments with cookbook methods that have been conducted in various experimental activities are considered not able to maximize the potential of students because it does not provide wide opportunities for students to explore. One of the solutions to develop the scientific reasoning skills of physics students is the problem solving-based experiment approach. The research was conducted by one group pretest-posstest design to 20 physics students as research sample. The research instrument used is the scientific reasoning instrument test developed by Lawson which is known as Lawson Classroom Test of Scientific Reasoning (LCTSR) and student work sheet instrument (LKM) containing problems in daily life and questions about: tools and materials, prediction, exploration, measurement, analysis and conclusions. The results show all aspects of scientific reasoning being measured, i.e. 1) conservation of matter and volume, 2) proportional thinking, 3) identification and control of variables, 4) probabilistic thinking, 5) correlative thinking, and 6) hypothetic-deductive thinking has increased. Based on the result of research can be concluded that the problem solving-based experiment can improve the scientific reasoning skills of physics students.

Combination of inquiry learning model and computer simulation to improve mastery concept and the correlation with critical thinking skills (CTS)

Among the purposes of physics learning at high school is to master the physics concepts and cultivate scientific attitude (including critical attitude), develop inductive and deductive reasoning skills. According to Ennis et al., inductive and deductive reasoning skills are part of critical thinking. Based on preliminary studies, both of the competence are lack achieved, it is seen from student learning outcomes is low and learning processes that are not conducive to cultivate critical thinking (teacher-centered learning). One of learning model that predicted can increase mastery concepts and train CTS is inquiry learning model aided computer simulations. In this model, students were given the opportunity to be actively involved in the experiment and also get a good explanation with the computer simulations. From research with randomized control group pretest-posttest design, we found that the inquiry learning model aided computer simulations can significantly improve students’ mastery concepts than the c...

Magnetic properties of soils from landslide potential area (Case study: Pasir Ipis-Lembang, West Bandung)

In this study we have analized magnetic properties of soils from landslide potential area. Top soil and four soil cores from Pasir Ipis as study area were taken as samples. All samples measured by rock magnetism method, magnetic susceptibility, to describe the characteristic of the physical property of samples. Magnetic susceptibility values of top soil samples are ranging from 193 × 10-8 m3/kg to 545 × 10-8 m3/kg, whereas for soil cores the magnetic susceptibility values range from 245 × 10-8 m3/kg to 674 × 10-8 m3/kg. It implies that the soil samples are dominated by ferrimagnetic minerals. Relative difference of magnetic susceptibility values measured at two frequencies or χfd f (%) for all samples range from 2 to 10%, indicating that the samples contain a mixture of ultrafine superparamagnetic grains and non superparamagnetic grains.

Magnetic Properties of Soils from Sarimukti Landfill as Proxy Indicators of Pollution (Case Study: Desa Sarimukti, Kabupaten Bandung Barat)

Leachate is the liquid arises from waste disposal. It contains heavy metals and magnetic minerals. Leachate could penetrate into sub surface that cause soil contamination. We have studied magnetic properties of soils from three zones in the Sarimukti landfill. We measured magnetic susceptibility in dual frequency and temperature dependent of susceptibility. The results showed that magnetic susceptibility at low frequency (xlf) of soil samples have the value ranging from 50-1400 (x 10-8 m3/kg). It infers that the samples were dominated by ferrimagnetic minerals. The relative difference of magnetic susceptibility measured at two frequency (xfd(%)) are less than 4%. It indicates that magnetic minerals probably derived from anthropogenic sources. There is negative correlation between xlf and Xfd(%). It supports the analysis that the source of magnetic minerals is anthropogenic. The results of the temperature dependent magnetic susceptibility measurements showed that the peak of magnetic susceptibility in heating curve occurs at the temperature about 200°C and 500°C. After 500°C, heating curve rapidly decreases. It can be inferred that the dominant type of magnetic minerals in the samples is titanomagnetite.

Subsurface Investigation in Sarimukti Landfill Using DC Resistivity

Layering process in landfill will produce leachate that produced by the entry of a mixture of rain water or ground water into the piles solid waste. In Sarimukti landfill, leachate from landfill channeled through a pipe to the leachate pond that planted beneath the soil surface. If the pipe is leaking, the leachate will contaminate the surrounding soil and may also to contaminate groundwater. Therefore, it is necessary to investigate subsurface conditions. One type of subsurface investigation can be determined by measuring the resistivity by using DC resistivity method. Resistivity measured in Sarimukti landfill with semigriding design including 8 lines perpendicular to each other. The result show there is resistivity contrast of materials, such as the solid waste, soil, water content that is predicted as leachate, and methane gas. The range of resistivity values are from 1 Ωm to 500 Ωm with variations of depth in according to line lenght. The resistivity values respectively: leachate is 1 to 10 Ωm; Wet soil is 10 to 100 Ωm; wet waste is 100 to 400 Ωm; gas is > 400 Ωm. Then, leachate was found at depth of 25 meters and wet soil is predicted as aquifer layer with 70 meters depth. The resistivity of aquifer layer is 1 to 20 Ωm and covered by silt clay as clay cap. Thus, it can predicted that leachate not seep into the aquifer layer.