OPAC - Artikel Jurnal & Majalah

Pengarang	:	-
Nama Majalah/Jurnal	:	The Physics Teacher
Volume / Edisi	:	62 (No. 3)
Halaman	:	205–209
Abstrak	:	Higher-education textbooks1–4 state that forces as physical entities are independent of the frame of reference, whenever it is inertial. It can be shown that the acceleration and Newton’s laws are invariant by Galilean transformations, but this fact is hardly addressed beyond the formalism. We designed an instructional experiment, based on images from videos of gliders sliding on an air track, to contextualize the conditions of application of Newton’s laws, the meaning of Galilean transformations, and the rationale of the second law. The interpretation provided here focuses on possible cause–effect relationships and the assumption of time simultaneity, and is aimed at teachers of introductoryphysics courses. The invariance of acceleration with the inertial frame of reference is approached in physics classes with deductions of expressions showing it; the algebraic simplicity of the “transformations” involved hides the profundity of the concepts and the importance of Galilean invariance in the architecture of Newtonian...

Pengarang	:	-
Nama Majalah/Jurnal	:	The Physics Teacher
Volume / Edisi	:	62 (No. 3)
Halaman	:	202-204
Abstrak	:	Mechanical waves are one of the fundamental models of classical physics and have numerous applications in science and engineering. In this work, we are going to analyze graphically what happens to the energy when two pulses traveling in opposite directions approach each other and destructively interfere. During an introductory lecture on waves, it is a well-known exercise to show pulses traveling in opposite directions along a stretched string and ask the students what happens when the pulses overlap. To explain the situation, the instructor draws snapshots of the string for different instants taking into account the principle of superposition for the pulses.1,2 Notice that if the pulses are of equal amplitude, but inverted, there will be an instant of time in the superposition in which the pulses completely cancel. An interesting question that can arise during class time, and that usually generates confusion in freshman students, is what happens...

Pengarang	:	Zhiwei Chong
Nama Majalah/Jurnal	:	The Physics Teacher
Volume / Edisi	:	62 (No. 3)
Halaman	:	199-201
Abstrak	:	Simple harmonic motion (henceforth SHM) is taught at various levels depending on students’ maturity in mathematics.1 Without delving into much mathematics, this paper qualitatively analyzes SHM based on elementary knowledge in kinematics, Newton’s second law, Hooke’s law, and mechanical energy conservation, which students are usually exposed to before the introduction of SHM. The results from the analysis are used to sketch the velocity vs. time curve, and the shape of the curve is largely determined by the fact that the tangent line slope on a velocity vs. time curve is the instantaneous acceleration. Even though the obtained curve is not proven to be sinusoidal here, it visually appears to be. The value of this approach is that key features of the seemingly complicated motion can be revealed to students who are not mathematically well prepared. Moreover, students are exposed to intensive physical reasoning rather than dry mathematical manipulations even...

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