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All Journal Kasuari: Physics Education Journal (KPEJ)
Devi Farah Dina
University of North Dakota
Education Physics

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Theoretical Analysis of Thermal Equilibration in a Rotating Solid Sphere Partially Immersed in a Hot Fluid: A Study Inspired by the Onde Cooking Process Rodika Utama; Moh. Toifur; Ishafit Ishafit; Devi Farah Dina
Kasuari: Physics Education Journal (KPEJ) Vol. 9 No. 1 (2026): June 2026
Publisher : Universitas Papua, Jurusan Pendidikan Fisika FKIP Unipa

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30862/kpej.v9i1.1053

Abstract

This study presents a theoretical analysis of thermal equilibration in a sphere rotating with a constant angular velocity, where part of the sphere is submerged in a hot fluid and the other part is exposed to air. The model is inspired by the traditional onde-onde cooking process, which illustrates temperature equalization through continuous rotation during heating. By applying the steady-state heat equation in spherical coordinates and imposing boundary conditions representing two temperature regions (the hot fluid at T1 and the air at T2), the criterion for rotational equilibrium is obtained. The result shows that the angular velocity must satisfy the minimum threshold ωmin=k/ρcR2, where k is the thermal conductivity, ρ is the density, c is the specific heat, and R is the radius of the sphere. When the actual rotation rate exceeds this limit, the temperature distribution becomes nearly uniform, and the entire sphere approaches thermal equilibrium. The findings clarify the physical mechanism through which rotation enhances temperature uniformity in partially immersed solids. Beyond its culinary analogy, the model offers valuable insight for rotating heat exchangers, industrial drying systems, and thermal homogenization in composite materials.
Exploring Misconceptions of Light and Shadow Formation among Senior High School Students: A Qualitative Study in Physics Education Nurlailah; Rodika Utama; Oki Mustava; Moh. Toifur; Devi Farah Dina
Kasuari: Physics Education Journal (KPEJ) Vol. 8 No. 2 (2025): December 2025
Publisher : Universitas Papua, Jurusan Pendidikan Fisika FKIP Unipa

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30862/kpej.v8i2.1028

Abstract

This study explores senior high school students’ misconceptions of light and shadow formation within the context of physics education. Despite being a fundamental concept in optics, many students continue to experience difficulties in understanding the principles of light propagation, the rectilinear nature of light, and the conditions required for shadow formation. This research employed a qualitative exploratory design involving 32 students from Grade X and XI science classes in Central Java, Indonesia. Data were collected through diagnostic tests and semi-structured interviews, which allowed in-depth identification of alternative conceptions. The analysis revealed three dominant categories of misconceptions: (1) perceiving light as a substance that “flows” from the source, (2) assuming that shadows are independent objects rather than regions of blocked light, and (3) misunderstanding the relationship between light intensity, distance, and shadow clarity. These findings confirm that students often rely on intuitive reasoning based on everyday experiences rather than scientific explanations. The discussion highlights the implications for physics instruction, particularly the need for teaching strategies that incorporate conceptual change models and inquiry-based learning to address students’ alternative frameworks. The study concludes that addressing misconceptions in optics requires not only emphasizing correct scientific principles but also engaging students in reflective and interactive learning processes that directly confront their prior conceptions.
Co-Authors Ishafit Ishafit Moh. Toifur Nurlailah Oki Mustava Rodika Utama