Static Course Research Articles

Validity of a self-report measure of student learning in active learning statics courses

Although faculty-centered pedagogies are endemic across undergraduate science, technology, engineering, and mathematics education, there is increasing interest in active learning approaches. As discipline-based educational research in mechanical engineering continues to assess strategies for improving student learning and development, researchers need data collection tools that ameliorate issues of bias, minimize costs (e.g. time and student attention), and provide reliable data that has been validated within the disciplinary context. This study analyzes the validity and reliability of a commonly used survey, the Students’ Assessment of their Learning Gains (SALG). Data from seven Introduction to Statics courses at two universities were used to identify and confirm the latent constructs of the measure and to assess their reliability and criterion validity. Results demonstrated that four scales—active learning, concept knowledge and skills, self-efficacy, and feedback mechanisms—explain the majority of variation in the SALG survey in relation to the teaching and learning of statics. These scales were statistically validated and shown to accurately capture the criterion they represent. The primary advantage of the SALG is that it is less burdensome to students, who are only required to spend 10 to 15 min once at the end of the course to complete the survey, rather than spending more time with longer surveys or with those that require completion at multiple points in time. The tool is therefore also less disruptive to the class, which may make it more likely that faculty will be willing to include data collection efforts in their courses.

ANALYZING THE ATTAINMENT OF COURSE OUTCOMES IN STATICS COURSE FOR DIPLOMA IN MECHANICAL ENGINEERING PROGRAM UiTM CAWANGAN PULAU PINANG DURING THE COVID-19 PANDEMIC

The outbreak of Covid-19 in 2020 had a significant impact on the delivery of educational courses, including lectures, labs, workshops, and assessments. In this study, the focus was on the Statics course, which is mandatory for all Diploma in Mechanical Engineering UiTM Cawangan Pulau Pinang students. The primary aim was to determine the achievement of course outcome (CO) during the pandemic. Three course outcomes were mapped for the methodology. The findings revealed that there were variations in the attainment of all COs, particularly CO3. Therefore, it can be concluded that the assessment of COs might have influenced the overall achievement rates for each CO.

Investigation of Progressive Learning within a Statics Course: An Analysis of Performance Retention, Critical Topics, and Active Participation

Previous research has demonstrated a link between prior knowledge and student success in engineering courses. However, while course-to-course relations exist, researchers have paid insufficient attention to internal course performance development. This study aims to address this gap—designed to quantify and thus extract meaningful insights—by examining a fundamental engineering course, Statics, from three perspectives: (1) progressive learning reflected in performance retention throughout the course; (2) critical topics and their influence on students’ performance progression; and (3) student active participation as a surrogate measure of progressive learning. By analyzing data collected from 222 students over five semesters, this study draws insights on student in-course progressive learning. The results show that early learning had significant implications in building a foundation in progressive learning throughout the semester. Additionally, insufficient knowledge on certain topics can hinder student learning progression more than others, which eventually leads to course failure. Finally, student participation is a pathway to enhance learning and achieve excellent course performance. The presented analysis approach provides educators with a mechanism for diagnosing and devising strategies to address conceptual lapses for STEM (science, technology, engineering, and mathematics) courses, especially where progressive learning is essential.

Self‐explanation activities in statics: A knowledge‐building activity to promote conceptual change

AbstractBackgroundThe complexity and diversity of problems and concepts in different engineering subjects represent a great challenge for students. Traditional approaches to teaching statics are ineffective in helping some students overcome the learning barriers that underlie learning statics and developing problem‐solving skills.PurposeThis article explores how self‐explanation activities may support student learning in statics. Specifically, this study examines the characteristics of student self‐explanations of worked examples and their relationship with students′ conceptual change.Design/MethodThe study population included 147 undergraduate engineering students enrolled in a statics course. The students wrote their self‐explanations at each step of an incomplete or incorrect worked example in the context of static equilibrium. Students′ self‐explanations were qualitatively analyzed using content analysis to identify the approaches used. We used descriptive and inferential statistics to identify differences in students′ conceptual understanding of statics, based on their approach to self‐explanation.ResultsWe identified four self‐explaining approaches: restricted explanations, elemental explanations, inferential explanations, and strategic explanations. After completing the activity, students who self‐explained incomplete worked examples showed better results in the quality of their explanations and conceptual change than students in the incorrect worked example condition.ConclusionsThe findings suggest a relationship between the type of worked example, students' approaches to self‐explaining, and their conceptual change and problem‐solving skills in statics. To increase the quality of the students' explanations and to improve their conceptual understanding, additional prompts or initial training in self‐explaining may be required within the worked‐examples context.

Exploring the effects of learning assistants on instructional team–student interactions in statics

Within a mechanical engineering curriculum, Statics is often a barrier course for students, as their performance in Statics can impact their overall academic success. Recent efforts to enhance students’ learning in fundamental engineering courses have included integrating learning assistants (LAs), undergraduate peers who have previously excelled in the course, into the course's instructional team. The purpose of this study is to explore one enactment of a Statics classroom with LAs, the interactions that characterize it, and the impact it has on the students and instructional teams. A qualitative case study of a statics course with LAs was conducted leveraging Kranzfelder and colleagues’ teaching discourse moves framework to deductively and inductively analyze the data collected. The value of having LAs within Statics was prevalent throughout the interactions and from the perspective of the LAs, instructors, and students. However, the LAs remained an untapped resources for many in the course. The results of this study have implications for mechanical engineering departments, Statics instructors and LAs, and research.

Investigating students' motivational goals and self‐efficacy and task beliefs in relationship to course attendance and prior knowledge in an undergraduate statics course

AbstractBackgroundStudent persistence in undergraduate engineering majors often depends on how they perform in foundational engineering courses. Although mastery of prerequisite knowledge affects how students perform in these courses, research suggests that achievement goal orientations and task‐value and self‐efficacy beliefs play prominent roles in predicting students' achievement.Purpose/HypothesisDrawing on achievement goal, expectancy‐value, and self‐efficacy theories, this study explores the relationships and relative predictive significance of students' achievement goal orientations and task‐value and self‐efficacy beliefs on academic achievement when prior knowledge and class attendance in a foundational engineering course were accounted for.Design/MethodParticipants were students enrolled in engineering statics at a primarily White institution. A multiple regression analysis was conducted using achievement goals, self‐efficacy for learning performance, task value, absence, and prior knowledge as predictor variables, and participants' achievement scores as the outcome variable.ResultsPositive relationships were observed between the different achievement goal constructs. The final regression model explained 50% of the variance in participants' achievement scores. Self‐efficacy and task‐value belief effects remained significant predictors of achievement, even after prior knowledge and regular class attendance were considered. Further, the combined effect of self‐efficacy and task‐value beliefs on achievement was larger than that of prior knowledge alone.ConclusionsPedagogical approaches that seek to improve engineering students' task‐value and self‐efficacy beliefs may be more efficacious at promoting achievement than those that focus on fostering achievement goal orientations. Instructors should consider such approaches along with those that effectively address differences in prior knowledge in foundational engineering courses.

ON THE ISSUE OF CLINICAL CLASSIFICATION OF PRECANCEROUS CHANGES IN THE ORAL MUCOSA AND THE LIPS

Diseases of the oral mucosa are an important and complex problem of dentistry. Due to the fact that diseases and pathological conditions of the oral cavity mucosa are diverse in etiology, pathogenesis, clinical manifestations, possible atypical course, have similarity of morphological elements, overall they characterized diseases of various organs and different body systems. In this regard, different methodological approaches are used for creating an optimal classification. P.T. Maksimenko (2012) indicated that each subsequent classification is statistical and intends to take into account diseases and pathological conditions.
 The existing classifications of the oral mucosa diseases have different principles of design. Diseases and lesions of the oral mucosa according to pathogenesis are divided into primary (own), secondary (symptomatic) and syndromes. In all classifications, one of the subset is precancerous changes.
 Nowadays in the world science literature sources there is a term "potentially malignant disorders of the oral cavity" (OPMDs). By this definition, it is recommended to replace the usual terms of precancer, epithelial precursor lesions, premalignant, precancerous, intraepithelial lesions. The definition of potentially malignant oral disorders is included in the WHO classification of Head and Neck Tumors (2017). In March 2020, this classification was supplemented at the WHO International Seminar on the Nomenclature and classification for Oral Cancer and included oral lichenoid lesions, chronic hyperplastic candidiasis and exophytic verrucous oral hyperplasia.
 In 2008, Maksimenko P.T. and co-authors created a working nomenclature and clinical classification of diseases, changes of the oral mucosa, lips and tongue. Symptoms and complexes symptom of the oral mucosa and lips, which are determined by visualization, in a separate section is mentioned the precancerous changes.
 Analysis of the 10-year work of the center for the diagnosis and treatment of diseases of the oral mucosa and the lips, organized at the Department of Dentists Postgraduate Education, made it possible to create some additions to this classification, taking into account atypically occurring precancerous changes and their malignancy. At the same time, regardless of changes in obligate and optional changes in clinical supervision, clinical signs of malignancy should be taken into account:
 
 static course of disease,
 progression of the lesion,
 increasing in the area of the lesion,
 increasing keratinization processes,
 disappearance of boundaries clarity,
 density of the lesion’s base,
 the occurrence of pain.
 
 As well as cytological and histological examination is crucial.
 Conclusion. According to the methodological principles of classifications, data’s of scientific research, information about previously unknown diseases and their manifestation in the oral cavity, it is possible to make additions to existing classifications, as well as to use international ones.
 Future perspectives. Clinical classification of precancerous changes in the oral mucosa and lips, and additions made to it made are very useful for clinicists in making a diagnosis, management of cancer, treatment of patients.

Clinical and economic impact of changing reimbursement criteria for statin treatment among patients with type 2 diabetes mellitus in South Korea.

Aim: Patients with type 2 diabetes mellitus (T2DM) in South Korea can be reimbursed for statins if they have a low-density lipoprotein cholesterol (LDL-C) level of ≥100 mg/dL. We aimed to explore the clinical and economic benefit received by T2DM patients when easing the current criteria for statin treatment by lowering the LDL-C threshold from 100 mg/dL to 70 mg/dL. Methods: We used a static course model with a 5-year period to compare the following two scenarios in T2DM patients with no history of cardiovascular (CV) events: the current criteria covering LDL-C ≥100 mg/dL and the revised criteria covering LDL-C ≥70 mg/dL. The number of target patients was estimated based on previous Korean studies on patients with T2DM. The current mix of treatments used for T2DM and costs involving CV events were estimated using the National Health Insurance Service–National Health Screening Cohort database. The baseline CV event rates and case fatality were estimated using NHIS Customized database, including 50% patients who were prescribed atorvastatin and 100% who were not prescribed statins between 2009 and 2012 among patients with T2DM in the entire Korean population. After propensity score matching, patients with T2DM not prescribed statins were followed up until 2018 to estimate the incidence rates of coronary heart disease (CHD) and stroke. The efficacy of atorvastatin for the primary prevention of CV events in patients with T2DM was derived from a pivotal clinical trial. The outcome measures were the number of CV events prevented after the change in criteria and the consequent cost savings. Results: In South Korea, the current and revised criteria covered 2,434,379 and 3,446,149 patients with T2DM, respectively. The change in criteria resulted in the prevention of 726 CV events and cost savings of US dollars (USD) 5.5 million at the national level and USD 0.0089 per member per month in the fifth year. Conclusion: Easing the reimbursement criteria for statin treatment among patients with T2DM was associated with a reduction in CV events and their related costs; therefore, changing the reimbursement criteria is worth further consideration to mitigate the burden of CV disease.

Publishing Student-Generated Problems in an OER

Fundamental engineering courses provide learning opportunities for students to develop problem solving and creativity skills, connect theoretical course material to the real-world, and solve complex, abstract problems such as those found in the workplace. Through a mixed methods study of students in a statics course in a small Canadian university, we explored student motivation and perception of composing and publishing their own course-relevant problems in an open educational resource (OER) textbook. We found that generating and solving their own problems for each of the six homework assignments helped students to anchor theory in the real-world, be creative, and understand the material more fully. In total, 93% of students in the course created at least one student-generated homework problem, and after the semester ended, 58% of students submitted a combined total of 59 high-quality, interesting, real-world examples to be included in the OER textbook. Of the 28 study participants, 26 students (93%) felt the activity should be repeated in future years. Students were motivated to publishing examples in the OER textbook by a desire to help future students and gain understanding of the material. Students found generating problems time-consuming, but enjoyed expressing their creativity.

SSPE in Children Younger than 3 Years

Subacute sclerosing panencephalitis (SSPE) is typically observed in school-going children, adolescents, and young adults. Herein, we report a 3-year-old boy of SSPE and systematically review all such reported cases (age ≤3 years). We searched PubMed database on June 16, 2020 with “English language & Human only” restrictions. Eligible publications were screened and retrieved by three authors (NK, SP, and RU). Variables like author, year of publication, country, age of onset, sex, duration of illness, immunization, history of measles, clinical presentation, neuroimaging, treatment, and outcome were extracted. Neurological outcome was assessed in terms of improvement, static course or death. The defined search criteria resulted in 791 manuscripts (1951 to June 16, 2020). Only 47 manuscripts were eligible for data extraction. Seventy cases were retrieved. The mean age of onset was 26.34 months. The M:F ratio was 3.2:1. Turkey (19 cases), India (10 cases), and Japan (10 cases) collectively comprised more than half cases of SSPE. Only six children were immunized, 17 have no measles immunization, and the rest 47 had insufficient immunization records. Preceding history of measles was present in 27 cases. Most patients presented in stage II/III with altered sensorium, myoclonic jerks, and seizures. The most common reported outcome was death (18/70) followed by vegetative state (10/70). The absence of measles vaccination is frequently associated with childhood SSPE. Early measles vaccination may prevent SSPE in toddlers. Perinatal measles infection results in short onset latency and fulminant course. Outcome was not good in reviewed age group of ≤3 years.

Amusement Industry Geotechnics

Wooden coasters have existed for over a century, steel coasters about the same. For as long as coasters have been around, so have coaster enthusiasts, some of whom purport the concept of negative g's. But those of you who hold the same opinion should go back and take a refresher course in statics and dynamics. By simple logic, there's no such thing as negative gravity because a person or an object cannot weigh less than zero. The confused coaster enthusiast mistakes weightlessness or “airtime” for negative g's.

Lessons Learned from Using Competency Based Assessment (CBA) in a First Year Engineering Statics Course

During the Fall term of 2020, the first year Statics course in the College of Engineering at theUniversity of Saskatchewan was taught remotely, and synchronously, using a competency-based assessment (CBA) implementation. CBA is commonly used in other professions, especially medical education and teacher education, but it has yet to see widespread use in engineering education.CBA can involve a number of key differences from conventional assessment practices. In this pilot, it involved the following key differences. Whereas previous versions of the course had involved assignments, labs, a midterm, and a final exam, each worth a certain weight in the overallcourse grade, the 2020 CBA version was broken into three modules, each with a “module test”. The module tests were superficially similar to a midterm, and there was no cumulative final exam. Open book assignments, quizzes, labs, and module tests consisted of questions and exercises that addressed a variety of learning outcomes (LOs) within the modules. The LOs were assigned weights in the overall course grade, as opposed to assigning weights to assessments themselves as in a conventional assessment system. Students could therefore overcome poor performances in early assessments of LOs, as better later results on the same LOs would replace the earlier results.A key feature of this approach was that students had at least two and typically three or more opportunities to exhibit competence with respect to the course’s LOs. Another key aspect of this CBA implementation was the division of course material into three levels or “types”. Type A materials were the most basic building blocks of the course i.e. basic definitions, calculations, and concepts. Type B materials were basic integrative problems e.g. solving a basic 2D or 3D particle or rigid body equilibrium question, or solving a basic truss. Type C materials were advanced or “tricky” integrative problems that probed deeper understanding and required more adaptive problem solving. Students were required to meet competency thresholds for Type A and B materials i.e. theyneeded to exhibit a minimal level of competency in the LOs in order to pass the course.Overall, the class excelled in this assessment format and anecdotal evidence suggests that the students enjoyed it. A summary description of the complete system will be presented in this paper, including how grades were determined, how assessments were conducted and evaluated, how LOs were determined, and how the three levels of material were arranged. As well, basic statisticalresults from the class’ performance will be presented, along with a number of observations made by the instructors and some anecdotal impressions conveyed to them by students. The observed outcomes will be compared with the CBA literature for related STEM contexts, although the remote learning/COVID context did obscure the causes and origins of some of the observed outcomes. Changes that will be made in next year’s implementation of the course will also be discussed.

Beam Analysis in Statics Courses Using ReshmoBeam

Beam Analysis in Statics Courses Using ReshmoBeam

The dynamics of an online learning community in a hybrid statistics classroom over time: Implications for the question-oriented problem-solving course design with the social network analysis approach

This study applied the question-oriented problem-solving (QOPS) pedagogy in Statistics learning and addressed several methodological and theoretical gaps in SNA studies to inform instructional and learning implications for teachers and students. The limitations in SNA studies included the lack of theoretical support in the analysis, the homogeneous medium where the data for SNA is collected, the constraints in the diversity of the network modes, and the lack of associations about the SNA measures with learning outcomes. Thus, we investigated 1) how a learning community based on social media evolved with the implementation of the QOPS activities, 2) changes in instructors and learners' roles in light of their one-mode and two-mode SNA measures, and 3) how different relational ties and SNA measures were associated with student outcomes. Participants were 23 graduate students (females: 52.17%) and an instructional team of three. Seven hundred four messages, including 118 posts and 586 comments, were collected from the private advanced statics Facebook learning group over an 18-week advanced Statics course. Aligned with the QOPS approach, the learning community became more interactive and cohesive, as reflected in their one-mode SNA measures. Besides, the two-mode measures, including density, GCC, reciprocity, transitivity, and strong/weak components, demonstrated that the learning community became denser and more interactive via their shared discussion. The instructional team played unique roles as a leader or facilitator in their interaction with students, while students' roles as a leader and coordinator were identified. Students' outdegree, degree, and closeness centralities have the most consistent predictive validity of their learning outcomes. Higher values in degree or closeness via shared discussion topics such as discussion of quizzes, help-seeking, and course administrative communication also predicted performance. The study results have practical implications for instructors and researchers in designing the hybrid learning environment and providing scaffolds to promote help-seeking.

New Idea to Enhance Better Understanding of Free Body Diagrams in Solid Mechanics Course

Historically, majority of students taking solid mechanics course at my university find it confusing and even challenging to draw free body diagrams (FBDs) and to compute the internal forces correctly. Many instructors teach those topics in typical statics course and review the same principles in solid mechanics and design courses. However, many students either do not still fully understand the topic or have forgotten the concepts during the time gap between taking statics and the follow on courses. This is also true for colleges such as ours with mandatory co-op education in which students alternate between school and work terms. With incorrect calculation of internal loads (or load in each section of a member), the next steps of calculating the stress and deflection of members will go wrong. In a recent solid mechanics course taught by the author, 60 to 70 percent of the students could not correctly compute the internal forces within each section of an axially loaded member. Although majority of students drew the free body diagram of the entire system correctly, only a few could realize or interpret the correct values of forces within each section of a member. Others drew incorrect FBDs that do not satisfy static equilibrium.The author came up with an idea (alternative approach or method) to teach free body diagrams that partially address the above-mentioned difficulties that many students face. Similar to axial loading, students find it difficult to determine the internal loads for torsional members. Determining the internal loads for beams subjected to complex loading is even more confusing and challenging to these students. Although the new method proposed in this paper is not fully assessed for its effectiveness, it was used during the Fall 2018 (September to December) and Winter 2019 (January to March) solid mechanics classes. The total number of students was around 50 in both academic terms. The students viewed this new method as one of the potential approaches to understand the equilibrium concepts. Same course will be taught by the author during Spring 2019 term to assess the effectiveness of the proposed method 'before and after' by giving the same problems to students using the old approach and to students using the new approach. Preliminary assessment results based on the students' performance on in-class, homework, quizzes and exams will be available by the end of Winter 2019 term. Active learning activities are being used to help teach the method. It is hoped that this alternative method will be an effective approach for instructors teaching statics and solid mechanics courses to make the struggling students better understand the concepts of static equilibrium. Details of this approach will be discussed in detail in this paper along with several numerical examples.

Chronic encephalopathy and locked-in state due to scrub typhus related CNS vasculitis

BackgroundScrub Typhus, prevalent in Asia-Pacific region, often has neurological manifestations in the setting of acute febrile illness, as acute encephalitis syndrome. Case reportA 20-year-old female, from western Rajasthan, India presented with calf pain followed by nausea, vomiting, dizziness, and sequentially progressive weakness of limbs, anarthria and loss of bladder control over 10 days. MRI Brain showed T2-weighted and FLAIR hyperintense lesions in corpus callosum, subcortical and periventricular white matter, basal ganglia, thalamus, brainstem and cerebellum producing starry sky appearance with diffusion restriction. Serum IgM for Scrub typhus was positive and patient progressively improved over 3 weeks with doxycycline. ConclusionsThis report highlights an unusual presentation of scrub typhus with subacute onset and static course, quadriparesis and locked-in state for 2 months, suspected based on red flags on neuroimaging and reversal of deficits with appropriate treatment.

On the use of three-force member concept versus equilibrium equations in Statics

ABSTRACT Use of three-force member concept for rigid bodies whenever possible, to circumvent the more taxing use of equilibrium equations has been long-established. However, most students fail to reap its benefits due to a number of reasons, including the fact that its importance is hardly emphasized to them; skills and details needed for the concept are missing in many undergraduate textbooks on Statics. This paper revisits and solidifies the understanding of three-force member in exploiting its potential for solving difficult problems. The paper addresses one of the most frequent students’ questions and concerns that the authors have faced in their experience of teaching Statics. This topic is revitalized herein, and its importance emphasized, to obviate the possibility of students’ wrong impression about its obsoleteness, by presenting detailed material in a pedagogical manner to serve as an addendum to any textbook for university undergraduate course in Statics. This serves as a good reference for both instructors and students in the course and eliminates their difficulty in accessing a concise document on the topic. Four examples, with increasing complexity, are solved where quicker and easier steps using three-force member concept are compared with the lengthier and relatively more difficult use of equilibrium equations.

Clinical Characteristics of Functional Movement Disorders in the Stomatognathic System.

Background: Functional (psychogenic) movement disorders often have distinguishable clinical features in the orofacial region. Tonic mandibular deviation accompanying ipsilateral downward and lateral lip pulling is the most common phenotype seen in patients with facial functional movement disorders. However, functional movement disorders in the stomatognathic system are underrecognized.Objective: This study aimed to evaluate clinical characteristics and phenomenology in patients with functional movement disorders in the stomatognathic system.Methods: Ten-item inclusion criteria (point range: 0–10) for functional movement disorders in the stomatognathic system was produced, based on previously established criteria for functional movement disorders and general signs of functional facial dystonia, to determine subject inclusion. The criteria included inconsistency, incongruence, and paroxysm in symptoms; rapid onset; distractibility; suggestibility; static course; spreading to multiple sites; spontaneous remission; and lack of sensory tricks. Fifty-eight patients [42 women (72.4%), 16 men (27.6%); mean age: 46.2 years] scored over 7 points on the criteria and were included in further analyses. Characteristic features, including the pattern and site of abnormal movements, were assessed in clinical examination.Results: Frequent items in the scale were inconsistent symptoms (93.1%), incongruous symptoms (91.4%), spreading to multiple sites (89.7%), paroxysmal symptoms (86.2%), and lack of sensory tricks (81%). Sixty percent of patients exhibited a pattern resembling dystonia. Some patients had a combination of organic and functional disease. Common involuntary movements included jaw deviation (74.1%), jaw closing (50%), lip pulling (34.5%), and tongue movement (31%). A functional dystonia phenotype (unilateral lower lip pulling and jaw deviation) was observed in 26 patients (44.8%). Characteristic features of functional stomatognathic movement disorders were rapidly repeating mandibular (lateral or tapping) and tongue movements (27.6%), which fluctuated in speed and direction.Conclusion: In 58 patients with functional movement disorders in the stomatognathic system, the functional dystonia phenotype was observed in 44.8%. Furthermore, 27.6% of patients showed the most characteristic type of functional stomatognathic movement disorders: very fast repeated jaw and/or lingual movements.

基于翻转课堂的专业课程思政探索——以《静态网站设计》课程为例

基于翻转课堂的专业课程思政探索——以《静态网站设计》课程为例

Helicopter blade droop as an application of simple beam theory

It is a commonly observed fact that the blades of a helicopter droop under their own weight when the aircraft is static but become almost straight when they start spinning. This phenomenon is commonly attributed to ‘rotational stiffness’. In this short article we present a simple calculation for the shape of the blades of a helicopter in static and rotating condition. We show that the deflection or droop of the tip of the blade reduces by a factor of about 30 when it changes from static to full-speed rotation. This calculation is at the undergraduate level and can complement a course in differential equations, elementary statics or elasticity theory.