arXiv subjects

Cecilia Stari

Publications and source records attributed to Cecilia Stari.

At least 19 recordsLinked to original sources

arXiv2026

Uniform and Accelerated Circular Motion with a Smartphone: A No-Code, AI-Generated Browser Laboratory

Smartphones have become a standard measurement instrument in the physics laboratory. Their built-in accelerometers, gyroscopes, magnetometers, and cameras have been used to investigate a wide range of phenomena in mechanics, and rotational motion in particular has proven especially well-suited to smartphone-based experiments. A recurring limitation, however, is that most experiments rely on precompiled sensor apps whose interfaces cannot be tailored to a specific activity, and until recently creating customized smartphone laboratories required programming knowledge beyond what most physics teachers possess. This paper makes two connected contributions. First, we present a validated smartphone experiment for uniform circular motion (UCM) and uniformly accelerated circular motion (UACM), in which the angular velocity and the angular acceleration are obtained from two independent smartphone channels and checked against independent video analysis with Tracker.10,14 Second, we show that generative AI can serve as a no-code development tool for the physics laboratory: the browser-based application used here was produced entirely through natural-language prompting, with no manual coding, extending to rotational motion the approach we recently introduced for acoustic experiments. The emphasis is therefore not only on what is measured, but also on how the measuring instrument itself was built.

physics.ed-ph↗

arXiv2026

Experimental observation of chaotic and multistable dynamics in a Duffing--Holmes--type analog circuit: antiperiodicity and attractor-coexistence signatures

An experimental study of a periodically forced Duffing--Holmes-type oscillator with a double-well potential, emulated by a piecewise-linear analog electronic circuit, is presented. By systematically varying the forcing amplitude and frequency, the full dynamical landscape of the system is characterized through bifurcation diagrams, Poincar\'e maps, and largest Lyapunov exponent calculations. The observed phenomenology includes period-doubling routes to chaos, periodic windows with multistability, intermittency, and antiperiodic orbits in which the trajectory recovers the global symmetry of the double-well potential. Multistability-induced discontinuities in the bifurcation diagrams are identified and interpreted as attractor-coexistence signatures arising from the sensitivity of the long-time dynamics to initial conditions, rather than as noise artifacts. These results are synthesized into a high-resolution two-dimensional map of the parameter space. The close agreement among all experimental diagnostics validates the fidelity of this analog implementation and demonstrates that continuous-time hardware provides a high-throughput platform for mapping complex nonlinear landscapes and resolving fine-scale multistable structures.

nlin.CD↗

arXiv2026

Phase-space organization of the elastic pendulum: chaotic fraction, energy exchanges, and the order-chaos-order transition

We study the phase-space organization of the planar elastic pendulum as a function of its two dimensionless control parameters: the reduced energy $R$ and the squared frequency ratio $\mu$. By randomly sampling the isoenergetic volume to classify trajectories as oscillatory, rotational, or chaotic across the $(\mu, R)$ parameter plane, we obtain a global portrait of the coexistence and competition between dynamical regimes. The chaotic fraction is not uniformly distributed across the parameter plane but concentrates in a well-defined central cloud whose ridge follows a linear relation in the $(\mu, R)$ plane and whose maximum does not exceed $70\%$ of the available phase space. The order-chaos-order transition is not a global property of the parameter plane but occurs specifically in the central region surrounding this cloud: along paths that traverse it, oscillatory orbits progressively give way to chaotic trajectories, which in turn yield to rotational orbits as the energy grows, revealing a clear sequential mechanism underlying the transition. The onset of rotational motion is gradual rather than sharp, reflecting a strong dependence on initial conditions. By decomposing the total energy into spring-like, pendulum-like, and coupling contributions, we establish a direct correspondence between the coupling power and the abundance of chaotic trajectories, showing that enhanced inter-mode energy exchange is a reliable indicator of dynamical complexity. These results provide a comprehensive and quantitative map of the dynamical regimes of the elastic pendulum, clarifying the structure of the chaotic cloud and connecting it to the underlying mode-coupling mechanisms.

nlin.CD↗

arXiv2026

Exploring the potential of ChatGPT for feedback and evaluation in experimental physics

This study explores how generative artificial intelligence, specifically ChatGPT, can assist in the evaluation of laboratory reports in Experimental Physics. Two interaction modalities were implemented: an automated API-based evaluation and a customized ChatGPT configuration designed to emulate instructor feedback. The analysis focused on two complementary dimensions-formal and structural integrity, and technical accuracy and conceptual depth. Findings indicate that ChatGPT provides consistent feedback on organization, clarity, and adherence to scientific conventions, while its evaluation of technical reasoning and interpretation of experimental data remains less reliable. Each modality exhibited distinctive limitations, particularly in processing graphical and mathematical information. The study contributes to understanding how the use of AI in evaluating laboratory reports can inform feedback practices in experimental physics, highlighting the importance of teacher supervision to ensure the validity of physical reasoning and the accurate interpretation of experimental results.

physics.ed-ph↗

arXiv2025

Enhancing Kinematics Understanding Through a Real-Time Graph-Based Motion Video Game

Kinematics is a core topic in early physics courses, yet students often struggle to interpret motion and its graphical representations. To tackle these difficulties, we developed MissionMotion, a physical-computational videogame where students reproduce target motion graphs using real-time data from their own movements or from sensors connected through micro:bit or Arduino. The system displays both the target and the user-generated graph, providing immediate visual feedback and a score based on similarity. We piloted the environment with ninth-grade students in different school contexts and evaluated their experience using the MEEGA+ instrument. The results show strong engagement, positive perceptions of usability, and evidence that the game promotes reflection on motion graphs in ways that rarely emerge in traditional lessons. MissionMotion runs on any web-enabled device and all materials are openly available, offering teachers an accessible tool to integrate experimentation, computational thinking, and playful learning into physics classrooms.

physics.ed-ph↗

arXiv2025

Enhancing Kinematics Understanding through a Video Game Based on Real-Time Motion Graphs

Interpreting kinematic graphs remains a significant challenge in physics education. The MissionMotion Project addresses this issue by providing a gamified physical-computational environment combining low-cost sensors, physical activity, computational thinking, and real-time visualization of motion graphs. This paper presents the design, development, and implementation of the project, with a particular focus on the pilot phase conducted with high school students in Uruguay. During this phase, we primarily used the MEEGA+ questionnaire to evaluate the gaming experience, usability, and motivation of the participants. Our analysis of the results shows high levels of satisfaction, perceived learning, and engagement, supporting the proposal's viability. Finally, we plan to conduct a large-scale conceptual evaluation to analyze how the proposal impacts understanding of kinematic graphs using standardized assessment tools.

physics.ed-ph↗

arXiv2025

Exploring the potential of ChatGPT for feedback and evaluation in experimental physics

physics.ed-ph↗

arXiv2025

Light intensity does not always decay with the inverse of the square of the distance: an open-inquiry laboratory

The square inverse law with distance plays an important role in many fields of physics covering electromagnetism, optics or acoustics. However, as every law in physics has its range of validity. We propose an open-inquiry laboratory where we challenge these concepts by proposing experiments where the intensity of light decays linearly or even remains constant over a range of distances. Using the light sensors built into smartphones, it is possible to measure light curves for different sources: point, linear, planar and even LED ring lights. The analysis of these curves allows us to discuss the limits of the physical theories. This low-cost laboratory, initially proposed in the context of the COVID19 pandemic, has the virtue of challenging intuition and encouraging the critical spirit of the students.

physics.ed-ph↗

arXiv2024

Basin of attraction organization in infinite-dimensional delayed systems: a stochastic basin entropy approach

The Mackey-Glass system is a paradigmatic example of a delayed model whose dynamics is particularly complex due to, among other factors, its multistability involving the coexistence of many periodic and chaotic attractors. The prediction of the long-term dynamics is especially challenging in these systems, where the dimensionality is infinite and initial conditions must be specified as a function in a finite time interval. In this paper we extend the recently proposed basin entropy to randomly sample arbitrarily high-dimensional spaces. By complementing this stochastic approach with the basin fraction of the attractors in the initial conditions space we can understand the structure of the basins of attraction and how they are intermixed. The results reported here allow us to quantify the predictability giving us an idea about the long-term evolution of trajectories as a function of the initial conditions. The tools employed can result very useful in the study of complex systems of infinite dimension.

nlin.CD↗

arXiv2024

A home-lab to study uncertainties using smartphone sensors and determine the optimal number of measurements

We present a home-lab experimental activity, successfully proposed to our students during covid19 pandemic, based on \textit{state-of-the-art} technologies to teach error analysis and uncertainties to science and engineering students. In the last decade the appearance of smartphones considerably affected our daily life. Thanks to their built-in sensors, this revolution has impacted in many areas and, in particular, the educational field. Here we show how to use smartphone sensors to teach fundamental concepts for science students such as any measurement is useless unless a confidence interval is specified or how to determine if a result agrees with a model, or to discern a new phenomenon from others already known. We explain how to obtain and analyse experimental fluctuations and discuss in relation with the Gaussian distribution. In another application we show how to determine the optimal number of measurements as a function of the standard error and the digital resolution of a given sensor.

physics.ed-ph↗

arXiv2024

Basin entropy as an indicator of a bifurcation in a time-delayed system

The basin entropy is a measure that quantifies, in a system that has two or more attractors, the predictability of a final state, as a function of the initial conditions. While the basin entropy has been demonstrated on a variety of multistable dynamical systems, to the best of our knowledge, it has not yet been tested in systems with a time delay, whose phase space is infinite dimensional because the initial conditions are functions defined in a time interval $[-τ,0]$, where $τ$ is the delay time. Here we consider a simple time delayed system consisting of a bistable system with a linear delayed feedback term. We show that the basin entropy captures relevant properties of the basins of attraction of the two coexisting attractors. Moreover, we show that the basin entropy can give an indication of the proximity of a Hopf bifurcation, but fails to capture the proximity of a pitchfork bifurcation. Our results suggest that the basin entropy can yield useful insights into the long-term predictability of time delayed systems, which often have coexisting attractors.

nlin.CD↗

arXiv2023

The Circular Atwood Machine

The Atwood Machine, a classic apparatus in physics education, has historically been pivotal in demonstrating Newtonian mechanics, specifically Newton's Second Law. This study introduces an innovative adaptation, the circular Atwood machine, aimed at exploring circular motion and angular dynamics and integrating emerging technologies, specifically smartphone sensors. Through a rotating disc subjected to controlled external torque, the experiment delves into the relationship between the torque applied and the resulting angular momentum. The study not only presents the theoretical framework but also outlines a practical setup using readily available materials, emphasizing the potential for contemporary technology to enhance the comprehension and teaching of fundamental physical concepts.

physics.ed-ph↗

arXiv2023

RLC series circuit made simple and portable with smartphones

This article presents a novel method for studying RLC series circuits using two smartphones, one used as a signal generator and the other as an oscilloscope. We measure the voltage at the external resistor as a function of frequency when subjected to a sinusoidal electromotive force. The experimental results demonstrate a remarkable agreement with the theoretical curve for the voltage at the resistor and the resonance frequency, validating the accuracy of the smartphone-based setup. The experiment fills the gap in educational materials related to electrical circuits and provides a portable alternative to traditional, expensive laboratory equipment.

physics.ed-ph↗

arXiv2023

The sensors of mobile devices: a innovative tool in the teaching of physical sciences

We show how builtin sensors in mobile devices can be used as portable laboratories at the service of teaching experimental sciences, especially physics, in the last years of high school and first years of university. We describe experiments that previously required expensive apparatus or were not feasible in teaching laboratories. Finally, we discuss some perspectives about the use of sensors in the physics teaching.

physics.ed-ph↗

arXiv2022

A home-lab experiment: resonance and sound speed using telescopic vacuum cleaner pipes

We propose a home laboratory in which a telescopic vacuum cleaner pipe and a smartphone are used to investigate sound speed and acoustic resonance. When the pipe is hit or the hands clapped near one end the sound produced is registered by a smartphone. By means of an appropriate application the resonant frequency is obtained. Varying the pipe's length and registering the corresponding resonant frequency allows to obtain the sound speed. This home-lab, first proposed during covid19 pandemic, has been incorporated as a home challenge to experiment with acoustic resonance in new normal times.

physics.ed-ph↗

arXiv2021

Simple physics behind the flight of a drone

The flight of a quadcopter drone, readily available as a toy, is analyzed using simple physics concepts. A smartphone with built-in accelerometer and gyroscope was attached to the drone to register the accelerations and angular velocities along the three spatial axis while the drone is taking off, landing or rotating. The vertical speed, the height and one of the angular coordinates are obtained through numerical integration of the acceleration values and compared with information provided by the manufacturer. The analysis of these quantities provides an opportunity to gain insight into important physics concepts involving Newton laws and conservation principles in a stimulating environment.

physics.ed-ph↗

arXiv2021

Characterizing multistability regions in the parameter space of the Mackey-Glass delayed system

Proposed to study the dynamics of physiological systems in which the evolution depends on the state in a previous time, the Mackey-Glass model exhibits a rich variety of behaviors including periodic or chaotic solutions in vast regions of the parameter space. This model can be represented by a dynamical system with a single variable obeying a delayed differential equation. Since it is infinite dimensional requires to specify a real function in a finite interval as an initial condition. Here, the dynamics of the Mackey-Glass model is investigated numerically using a scheme previously validated with experimental results. First, we explore the parameter space and describe regions in which solutions of different periodic or chaotic behaviors exist. Next, we show that the system presents regions of multistability, i.e. the coexistence of different solutions for the same parameter values but for different initial conditions. We remark the coexistence of periodic solutions with the same period but consisting of several maximums with the same amplitudes but in different orders. We characterize the multistability regions by introducing families of representative initial condition functions and evaluating the abundance of the coexisting solutions. These findings contribute to describe the complexity of this system and explore the possibility of possible applications such as to store or to code digital information.

cond-mat.dis-nn↗

arXiv2020

Using mobile-device sensors to teach students error analysis

Science students must deal with the errors inherent to all physical measurements and be conscious of the need to expressvthem as a best estimate and a range of uncertainty. Errors are routinely classified as statistical or systematic. Although statistical errors are usually dealt with in the first years of science studies, the typical approaches are based on manually performing repetitive observations. Our work proposes a set of laboratory experiments to teach error and uncertainties based on data recorded with the sensors available in many mobile devices. The main aspects addressed are the physical meaning of the mean value and standard deviation, and the interpretation of histograms and distributions. The normality of the fluctuations is analyzed qualitatively comparing histograms with normal curves and quantitatively comparing the number of observations in intervals to the number expected according to a normal distribution and also performing a Chi-squared test. We show that the distribution usually follows a normal distribution, however, when the sensor is placed on top of a loudspeaker playing a pure tone significant differences with a normal distribution are observed. As applications to every day situations we discuss the intensity of the fluctuations in different situations, such as placing the device on a table or holding it with the hands in different ways. Other activities are focused on the smoothness of a road quantified in terms of the fluctuations registered by the accelerometer. The present proposal contributes to gaining a deep insight into modern technologies and statistical errors and, finally, motivating and encouraging engineering and science students.

physics.ed-ph↗