Work-energy Theorem Research Articles

ACTIVATION OF STUDENT RESOURCES REGARDING THE WORK-ENERGY THEOREM

Students' understanding of physics will increase along with learning during lectures, but thoughts on this understanding can be flexible and not always permanent, so it is necessary to explore other students' thoughts (resources) that may not have been discussed in previous research. This article focuses on the conceptual analysis of resources, namely the ideas they use in solving problems related to work-energy issues. This research aims to identify the resources used by physics students in work-energy reasoning as a work to explore students' new thoughts that have not been discussed in previous research. The research was conducted on 92 new physics department students in 2023 who took Basic Physics I lectures. Before the test was given, the lecturer gave a short review of the work-energy theorem to remind them of the knowledge they had learned in high school. The results of the research reveal that the resources that are widely used by students are (1) the concept of work in physics which is associated with the understanding of work in everyday contexts, namely as work/work/work, (2) in reasoning about motion phenomena involving potential energy and kinetic energy for students. directly apply the principle of conservation of mechanical energy. It is hoped that these findings will be useful input for lecturers in designing lectures on the topic of work-energy theorem based on resource theory or knowledge in pieces.

Energy loss comparison between kinematically equivalent mechanisms: Slider-crank and eccentric cam

The reduction of energy consumption in industrial processes is a challenge to be confronted within the framework of the United Nations’ Sustainable Development Goals. The present study compares the energy loss per cycle of two kinematically equivalent mechanisms: a slider-crank and an eccentric cam with a translational roller follower. We use the work-energy theorem to evaluate energy losses by using a viscous friction model in a stationary regime. The innovation of this study lies in the energetic comparison to identify the best and worst alternatives by analyzing the contribution of their main geometrical parameters, such as crank length, rod-crank length ratio, roller radius and follower offset. The aim is to provide guidelines to help machinery designers to take relevant preliminary decisions that affect energy efficiency. Herein, we include analytical models, numerical simulations and experimental results using a test stand that can be adapted to other planar one degree-of-freedom mechanisms. In this context, we conclude that an eccentric cam mechanism with a big roller radius and no offset provides the best energetic efficiency among the aforementioned mechanisms.

Hollywood Trial Features Kinematics and the Work–Energy Theorem

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Dan MacIsaac; Hollywood Trial Features Kinematics and the Work–Energy Theorem. The Physics Teacher 1 May 2023; 61 (5): 415. https://doi.org/10.1119/10.0018004 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAmerican Association of Physics TeachersThe Physics Teacher Search Advanced Search |Citation Search

Assessment of student knowledge integration in learning work and mechanical energy

Work and mechanical energy is a fundamental topic in introductory physics. Studies in existing literature have shown that students have difficulties in understanding work and mechanical energy, particularly the topic of work-energy theorem. To study students’ knowledge integration in learning work and mechanical energy, a conceptual framework model of work and mechanical energy was developed and applied to guide the design of an assessment for measuring students’ level of knowledge integration. Using the assessment, qualitative and quantitative data were collected in two high schools in an eastern Chinese city. The results reveal that the conceptual framework model can effectively represent the students’ knowledge structures at different levels of knowledge integration. In addition, the assessment is shown effective in identifying unique features of knowledge integration, including context dependence and fragmentation of knowledge components, memorization-based problem-solving strategies, and lack of meaningful connections between work and change in kinetic energy. The conceptual framework of work and mechanical energy and assessment results can provide useful information to facilitate instructional designs to promote knowledge integration.Received 13 January 2023Accepted 16 March 2023DOI:https://doi.org/10.1103/PhysRevPhysEducRes.19.010127Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAssessmentConcepts & principlesPhysics Education Research

A new rolling friction coefficient measurement method based on the work-energy theorem

The rolling friction coefficient represents a characteristic parameter for the rolling motion. To determine the rolling friction coefficient, we propose a simple method based on the conservation of energy. The measuring setup includes the tools and materials that are simple and easy to obtain, such as the spring, ruler, and a small laboratory wheeled cart. In this paper, we have determined the rolling friction coefficient for several masses of the test carts and different lengths of spring compression. When the spring is compressed, its energy is directly proportional to the square of the length of the spring compression. The initial speed of the cart was determined using the law of energy conservation, and the length that the cart goes before stopping is measured with a ruler. The conclusion is that the value of the rolling friction coefficient is usually very small and that the mass of an object will affect the friction force but will not affect the rolling friction coefficient. Besides determining the rolling friction coefficient, this technique should help students comprehend the concept of friction easily.

Energy equations for projectiles with linear and quadratic drag

Although linear and quadratic drag are treated early in upper-level undergraduate mechanics courses, energy dissipation due to drag is not. In this paper, energy equations with exact analytic formulas for dissipation due to air resistance are developed for projectiles using linear and quadratic drag models, based on the work–energy theorem. Examples with analytic results for specific cases are presented for quadratic drag in one dimension, and linear drag in one and two dimensions suggested as student assignments. Similarly, three numerical examples of energy dissipation showing kinetic, potential, and/or dissipated energy versus either time or distance are presented, suggested as assignments that students could code and graph in a spreadsheet application.

Evaluation of path-dependent work and internal energy change for hysteretic mechanical systems

The accuracy of procedures for the analysis and design of hysteretic mechanical systems, in which both generalized rate-dependent and rate-independent hysteretic forces have a non-conservative nature, can be significantly improved by a straightforward computation of work and energy terms. Thus, with the aim of shedding light on the definition and evaluation of work and energy components, we first derive the nonlinear equilibrium equations of a conventional family of MDOF hysteretic mechanical systems and, subsequently, we introduce the modified work-energy theorem. In addition, to allow for a forthright evaluation of path-dependent work and internal energy change associated with generalized rate-dependent (rate-independent) hysteretic forces, we derive the related (closed form) expressions by adopting the Seleemah and Constantinou (Vaiana and Rosati) model. The former is capable of simulating both linear and nonlinear rate-dependent hysteretic responses; the latter can simulate a great variety of rate-independent hysteretic behavior, characterized by symmetric, asymmetric, pinched, S-shaped, flag-shaped hysteresis loops or by an arbitrary combination of them. Finally, several nonlinear dynamic analyses are performed on a MDOF hysteretic mechanical system to clearly describe its free vibration and forced harmonic vibration responses in terms of work and energy quantities.

Quantification of cell contractile behavior based on non-destructive macroscopic measurement of tension forces on bioprinted hydrogel

Contraction assay based on surface measurement have been widely used to evaluate cell contractility in 3D models. This method is straightforward and requires no specific equipment, but it does not provide quantitative data about contraction forces generated by cells. We expanded this method with a new biomechanical model, based on the work-energy theorem, to provide non-destructive longitudinal monitoring of contraction forces generated by cells in 3D.We applied this method on hydrogels seeded with either fibroblasts or osteoblasts. Hydrogel mechanical characteristics were modulated to enhance (condition HCAHigh: hydrogel contraction assay high contraction) or limit (condition HCALow: hydrogel contraction assay low contraction) cell contractile behaviors. Macroscopic measures were further correlated with cell contractile behavior and descriptive analysis of their physiology in response to different mechanical environments. Fibroblasts and osteoblasts contracted their matrix up to 47% and 77% respectively. Contraction stress peaked at day 5 with 1.1 10−14 Pa for fibroblasts and 3.5 10−14 Pa for osteoblasts, which correlated with cell attachment and spreading. Negligible contraction was seen in HCALow. Both fibroblasts and osteoblasts expressed α-SMA contractile fibers in HCAHigh and HCALow. Failure to contract HCALow was attributed to increased cross-linking and resistance to proteolytic degradation of the hydrogel.

Entire-Structure-Oriented Work-Energy Theorem (ES-WET)-Based Characteristic Mode Theory for Material Scattering Objects

Entire-structure-oriented work-energy theorem (WET) framework is used to establish the characteristic mode theory (CMT) for material scatterers. Diagonalizing driving power operator (DPO) method is proposed to calculate characteristic modes (CMs). Solution domain compression (SDC) scheme is introduced to suppress spurious modes. An electromagnetic energy characteristic equation similar to the energy eigen-equation in quantum mechanics is derived for unifying the modal analysis theories of classical electrodynamics and quantum mechanics. Using the concept of driving power in the WET framework, the physical meaning of characteristic values is revealed; the reason leading to the nonorthogonal characteristic far fields of lossy scatterers is provided; it is explained why the conventional CMT fails to analyze some classical transmitting antennas; the physical interpretation for normalizing modal real power to 1 is given; the Parseval’s identity in CMT is derived; the classical concept of quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -factor) is generalized to a novel concept of field-current phase-mismatching factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Theta $ </tex-math></inline-formula> -factor). Using the diagonalizing DPO method with the SDC scheme, the spurious modes outputted from the conventional diagonalizing impedance matrix operator method are suppressed. Both the novel SDC and conventional dependent variable elimination schemes confirm the same conclusion that the spurious modes originate from overlooking the dependence relationships among the currents in CM-generating operator.

The concept of energy in the analysis of system dynamics models

AbstractThis paper applies for the first time the Newtonian concept of energy to stock–flow systems and employs it to relate system behaviour to model structure. Kinetic energy and work done are defined analytically using the concepts of loop impact and force from the Newtonian Interpretative Framework and are examined numerically within system dynamics simulations. The energy analogy is used to analyse models by understanding how loops of different orders and types act as energy sources, sinks and exchange, using the system dynamics equivalent of the work–energy theorem. It is shown that energy describes the cumulative effects of feedback on stock behaviour, in contrast to the instantaneous description given by existing methods of loop dominance. This approach gives additional insight over that of existing dominance methods, capturing the dynamical influence of loops even when not dominant. The analogy's explanatory power provides quantitative and informal analysis. © 2022 The Authors. System Dynamics Review published by John Wiley &amp; Sons Ltd on behalf of System Dynamics Society.

Optimization Technique for Reducing Energy Consumption of Rapid Transit Mode

Abstract: Since the time, our mother earth was created, energy was taken from the universe(System),now energy is being depleted as non-renewable source. Energy can neither be created nor be destroyed as it transforms in one form to another. So researchers came up with renewable source of energy as the solution like solar, wind and tidal waves. The world is experiencing an energy crisis and the prices of petroleum products like petrol and diesel has gone up. So its time to come forward and save the future of our mother earth. The paper deals in reducing energy consumption of rail rapid transit mode i.e. of metro. It shows how driving behaviour can be controlled using optimized speed profile and efficiency can be managed. It states round trip data taken of Mumbai(India) metro from Versova to Ghatkopar and viceversa. Speed data was taken from GPS(Global Postioning System) embedded in Smart watch Software. Time interval was noted and distance, acceleration data was formulated using Newtons Equations of Motion. Energy Consumed was drawn out from tractive effort data. Then efficiency, energy lost and regenerative braking energy was calculated using Work Energy Theorem. Maximum efficiency of 88.27% was obtained between Asalpha to Jagruti Nagar Station while between Western Express Highway to Andheri Station a 72.66% efficiency was analysed. This affects the time interval of metro trains arriving at station, also the amount of boarding and alighting passengers from the train. A model was designed and simulated using results obtained. The paper also deals with the prototype of Regenerative energy which can either be used in braking systems but also for acceleration and cruising purpose. The idea can benefit a developing country like India where 6.3% GDP is from Transportation Industry. Keywords: optimized speed profile, efficiency, regenerative braking energy

Tracker-assisted modelling: simultaneous validation of the conservation law of energy and the work-energy theorem

The video of a free-falling object was analysed in Tracker in order to extract the position and time data. On the basis of these data, the velocity, gravitational potential energy, kinetic energy, and the work done by gravity were obtained. These led to a rather simultaneous validation of the conservation law of energy and the work–energy theorem. The superimposed plots of the kinetic energy, gravitational potential energy, and the total energy as respective functions of time and position demonstrate energy conservation quite well. The same results were observed from the plots of the potential energy against the kinetic energy. On the other hand, the work–energy theorem has emerged from the plot of the total work-done against the change in kinetic energy. Because of the accessibility of the setup, the current work is seen as suitable for a home-based activity, during these times of the pandemic in particular in which online learning has remained to be the format in some countries. With the guidance of a teacher, online or face-to-face, students in their junior or senior high school—as well as for those who are enrolled in basic physics in college—will be able to benefit from this work.

Average force obtained from the impulse or from the mechanical work?

In this paper, we propose a simple relationship between the average values of the force obtained from the mechanical impulse theorem and the mechanical work-energy theorem. It is an example proposed to the students with the purpose they do not erroneously apply formulas that automatically they are proned to apply to solve a problem making use of the preconception that all motion is uniformly accelerated. The solution to the problem is simple and allows addressing the interconnection between two fundamental theorems of classical mechanics that usually is hidden in the textbooks. We have simplified the problem to one dimension to make it more didactic, being its generalization to three dimensions inmediate.

Theoretical trafficability criterion and diagrammatic analysis based on rheological property of sea-floor sediment and topography

Trafficability criterion of a tracked miner is investigated when walking across deep-sea floor with obstacles by analyzing the mechanical property of deep-sea sediment and geometrical conditions of obstacles. Trafficability criterion can help predict and estimate the mining efficiency and working safety of the tracked miner on the deep-sea sediment. Deep-sea sediment has an obvious rheological property and its compression-sinkage-time relationship was adopted to describe the sinkage shape of track under different grounding pressure distributions. The area of the sinkage shape was classified and redefined according to the relationships with different traction forces based on work-energy theorem concept. A new trafficability criterion is then established based on the areas of sinkage shapes and the physical meaning of parameters in the criterion was explained diagrammatically in detail. As an application, a trafficable deep-sea ditch width and slope angle were calculated theoretically by combining the trafficability criterion and sinkage shapes analyses. The trafficability criterion is proved to be convenient and intuitive for quickly judging the trafficability problem of deep-sea tracked miner for common obstacles.

Students’ conceptual understanding and problem-solving of the Work-Energy and Impulse-Momentum Theorems in a flipped classroom

The study investigated the effect of using a flipped classroom approach on students’ understanding of the work-energy and impulse-momentum theorems. An intact class of Grade 12 STEM students took part in the study. The instructional materials needed for the lessons were compiled in a website that can be accessed by the students via desktop or a mobile device. The lesson calendar, study guide, modules, worksheets, and problem sets were organized in tabs and instructions were clearly stated for ease of use. Using Greeno’s model of scientific problem-solving and reasoning, the students’ solutions were analysed using maps of the problem-solving approaches they utilized. The students had difficulty comprehending problems and identifying which concepts are related to them. In terms of Greeno’s model, this implies that the students were not able to successfully translate concepts between domains. There were no traces of use of other domains apart from the abstract and symbolic domains, when an improved understanding must include translations between all four domains – namely, the concrete domain, which involves physical objects or events; the model domain, which refers to representations of objects or events; the abstract domain, which involves concepts or principles; and the symbolic domain, which is the mathematical representation of concepts.

Arduino-based STEM education material: work-energy theorem

Twenty first century expertise often requires high-level and cross-disciplinary skills that ought to be a part of todays’ educational activities. Therefore, educational undertakings should be designed in such a way that students can gain the desired expertise and skills. The present work offers an Arduino-based STEM education material, specifically designed to teach the work–energy theorem. The designed physical system is experimentally resolved by directly measuring position-time trajectories which lead to instant velocities. Measured instant position values are employed to determine the amount of work and corresponding velocity values are used to determine the instant kinetic energies of the system. Experimental data, on average, lead to a ratio of 0.959 which is reasonable concerning the range of experimental error limits therefore smartly validating the work–energy theorem.

Simulation Modeling of the Tilting Mechanism of the Main Trolley of the Turnaround Charging Crane

this article contains kinematic and dynamic analysis of the tilting mechanism of the turnaround charging crane main trolley, conducted with the use of the Mathcad package. The mechanism is modeled by a flat link mechanism – a four-bar linkage. In the same time, the analysis of the mechanism is also conducted using the Matlab Simulink environment and the tools of Multibody, which is a Simulink library. These two models were then compared. In the study the work-energy theorem and Holonomic constraints equations were used.

Collecting data with a mobile phone: Studies of mechanical laws such as energy and momentum conservation

We use videos taken with a mobile phone to study conservation of energy, conservation of momentum, and the work-energy theorem by analyzing the collision of a cue ball and the eight ball. A video of the full time sequence, starting from before the cue ball is struck until well after the collision, is recorded with a mobile phone. The video is imported into Origin (free to teachers and students taking a class) [OriginLab Corporation, Origin, Version 2020 (OriginLab Corporation, Northampton, MA, USA, 2020)], where the coordinates of the balls are digitized frame-by-frame using the free Video Extractor app. From these data, the velocities are determined as a function of time and used to determine the energy and momentum of each ball. The data suggest that the balls slip through part of their motion when rotating at an angular velocity different than the rolling angular velocity, so angular momentum and frictional torque must be considered. Such experiments require no specialized equipment other than a device to take a video, and the act of digitizing the data provides the student with visual reinforcement of the physics. Experimentation by students outside of campus can be fun for them and provides a useful alternative to classes when in-lab experiments are not practical. Use of a mobile phone in this way is generally applicable to any other mechanical phenomena that involve motion.

A model for calculating the mechanical demands of overground running

ABSTRACT An energy-based approach to quantifying the mechanical demands of overground, constant velocity and/or intermittent running patterns is presented. Total mechanical work done (Wtotal ) is determined from the sum of the four sub components: work done to accelerate the centre of mass horizontally (Whor ), vertically (Wvert ), to overcome air resistance (Wair ) and to swing the limbs (Wlimbs ). These components are determined from established relationships between running velocity and running kinematics; and the application of work-energy theorem. The model was applied to constant velocity running (2–9 m/s), a hard acceleration event and a hard deceleration event. The estimated Wtotal and each sub component were presented as mechanical demand (work per unit distance) and power (work per unit time), for each running pattern. The analyses demonstrate the model is able to produce estimates that: 1) are principally determined by the absolute running velocity and/or acceleration; and 2) can be attributed to different mechanical demands given the nature of the running bout. Notably, the proposed model is responsive to varied running patterns, producing data that are consistent with established human locomotion theory; demonstrating sound construct validity. Notwithstanding several assumptions, the model may be applied to quantify overground running demands on flat surfaces.

Analysis of students’ difficulties about work and energy

Identification of students’ difficulties is an important part of designing a quality learning. This research used survey method that aims to identify the difficulties experienced by students in understanding the concept of work and energy. The research subjects consisted of 142 undergraduate students in physics education (46 first-year students, 39 second-year students, and 57 third-year students). Data collection was carried out from 2018-2019. There are 10 multiple choices questions that are used to uncover the difficulties experienced by students. Based on the results obtained it can be concluded that many students still have difficulty in understanding the concepts of work and energy. The percentage of students who answered correctly are 20.42% in concept of work as a result of dot product multiplication; 11.26% in the work-energy theorem; 38.03% in the concept of spring potential energy, and 22.54% in the conservation law of mechanical energy.