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Measuring the speed of sound in water is a typical experiment in undergraduate physics laboratory courses. The resonance of ultrasonic waves can be used to determine the wavelength, thereby calculating the speed of sound. It is generally considered that the ultrasonic wave reflected on the surface of the receiver interferes with the incident ultrasonic wave. Resonance occurs when the distance between the two transducers is an integer multiply of the acoustic half-wavelength. However, the residual distribution of the experimental data and the abnormal raising of receiving signal amplitude show that the simple standing wave model is not enough to describe this experiment. Considering the multiple reflections of ultrasonic waves between the transmitting and receiving transducers, and the reflection of ultrasonic waves on the water-air interface, an improved model is proposed. The simulation results show that the height of the water has a great influence on the abnormal experimental phenomena.

AAPT WM 21

An Improved Model for Measuring the Speed of Sound

reflection on the water-air interface

multiple reflections

measuring the speed of sound

## Dr. Nishikant (Nish) Sonwalkar: Academician, Scientist, Musician

![](https://assets.underline.io/uploads/markdown_image/1/image/0f9b63a0b3deba4a355d98e2c87af68a.png)

Dr. Sonwalkar is regarded as a leading expert in the application of computers in education. He has extensive research and development experience in hypermedia authoring, mobile learning, adaptive learning, and brain-based synaptic learning, advanced scientific visualization, database management systems, and computer simulation.

After receiving doctoral degree from MIT in the area of Molecular Dynamics of Nano-interfaces, he joined MIT as faculty in Mechanical Engineering, but his passion for technology enabled education led him become the founding director of Hypermedia Teaching Facility (Hypermedia Lab) at MIT and later he was appointed as the Principal Educational Architect of MIT.

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NISH 2021

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Higher education institutions play a critical role in preparing students to be future STEM leaders, yet significant inequities remain in which students persist and thrive in STEM. Hispanic Serving Institutions (HSIs) have both an outsized opportunity to support racially minoritized STEM learners and distinctive structural challenges that need to be considered. In this talk, I will share practical recommendations for cultivating lasting STEM instructional change at HSIs. These recommendations are distilled from my experiences designing and starting to implement a $2.5 million college-wide change effort with a team at my home institution, as well as my participation in the institutional change research community. They include the importance of creating a theory of change, coordinating multiple change strategies, drawing on targeted research about supporting racially minoritized learners, forming and building up positive relationships with administrators, fostering communities of practice among&nbsp;faculty and students, and constantly keeping your long-term goals in mind.

Practical Recommendations for Cultivating Sustained STEM Instructional Change at HSIs

California State University San Bernardino (CSUSB), a HSI located in Southern California’s Inland Empire, recently underwent a relatively unique opportunity to transform the physics curriculum as part of the university’s transition from quarters to semesters. This afforded our department to take a close look at our student population, learning outcomes, and overall mission in order to create new programs focused on student success and preparing them to enter a variety of fields, serving both local needs and a national priority of diversifying the STEM workforce. In this talk I will detail and reflect on our process of transformation and give specific examples of new courses (e.g. first-year seminar, new upper division labs) or approaches to teaching that we hope will benefit our departmental community. I will also discuss external funding programs and other resources we have tapped into to enhance opportunities available to our students.

Progammatic Transformation for Student Success at a Southern California HSI

This poster presentation focuses on the balanced mix of lecture-based teaching and project-based learning in introductory college physics courses for life science majors. Students naturally resist active learning approaches because they put more responsibility on the learner to master the content. If the lectures still cover the content, the accompanied labs practice the concepts hands-on, and instead of final exams, students are charged with final projects, they apply all of the learned concepts into problem-solving and trouble-shooting with a final product available at the end of the process. Students learn more than the physics concepts: they also learn patience, trial and error, time management, and many other life lessons

Active learning in college physics: it takes two to tango

Simple epidemiological models are introduced using finite difference methods in Excel. The resulting SIR model is then fit to published COVID-19 infection rate data for the United States using least-squares techniques. Using their own spreadsheets, students discover that the SIR model explains: the initial exponential growth of COVID-19; the effects of social distancing during April and May 2020; and the summer surge caused by prematurely lifting social distancing. The SIR model is the origin of the basic reproduction number R 0 and the concept of herd immunity. A wide range of student research projects are possible to make quantitative predictions based on published data for US states and other countries, including: predicting the benefit of implementing social distancing earlier; predicting how many lives were lost because people didn’t wear masks; the nascent fall surge; and the effect of a potential vaccine. See http://circle4.com/biophysics for free textbook chapters and instructional videos.

Modeling the coronavirus pandemic in the United States

Teaching traditional introductory physics courses to pre-health and life science students has been a challenge for students who find it difficult to connect physics concepts with bio-medical applications. This, in addition to, large class sizes, students with diverse skills in math, problem-solving, conceptual reasoning, and learning styles makes it even more challenging. Using biomedical examples, applications, and videos from experts in the bio-medical field throughout the course and providing interactive activities such as simulations, concept questions and problems with scaffolding questions along with support for students with different learning preferences and skill levels has potential to promote active and engaged learning to have a long-lasting impact on the students’ educational experience. We will discuss the curricular development and the first all remote implementation of the course on the online platform “Cogbooks”. The talk will conclude with our observations and experiences from the first &nbsp;course on mechanics. &nbsp; &nbsp;

Introductory Physics for Pre-health Students on an Adaptive, Interactive Platform

The traditional introductory physics course doesn’t work for life-science students. Life-science students don't find kinematics or Newton’s laws to be relevant to their interests. That, combined with the well-known conceptual problems associated with describing motion mathematically, suggests the need for a new starting point for the Introductory Physics for Life Sciences (IPLS) course. This presentation outlines a new pedagogical approach for life-science students. It starts with the “marble game,” which simulates diffusion – a topic students already know is fundamental to biology. Modeling techniques introduced with the marble game are then applied to drug elimination; radioactive decay; osmosis; the Boltzmann factor; ligand binding; thermodynamics, phase equilibrium and entropy; membrane voltage, RC circuits and the action potential; models of COVID-19; and yes, even Newtonian mechanics. I’ve been successfully using this approach with IPLS students for over 5 years. See http://circle4.com/biophysics for free textbook chapters and instructional videos.

IPLS – the physics that life-science students want and need

An important learning goal for IPLS students is to have them see physics as a way of learning reasoning rather than facts. Unfortunately, many students expect the latter and resist the former. The most critical step is to shift them away from "answer making" to "sense making." A good way is to elicit a mistake, confront it, and scaffold a resolution.[1] But if students see mistakes as shameful instead of an opportunity to learn, this approach can result in strong negative reactions. I frame the class as "reasoning not answers" on the first day by teaching basic psychological principles of memory and decision making [2] using common surprising illusions. I introduce mantras that we use throughout including [3]: "one-step thinking", "missing the gorilla", and "debugging your thinking." These help students begin to see errors as valuable learning tools instead of as an embarrassment and to engage with sense-making.

Why I teach Psychology on IPLS day 1

Transforming an introductory physics class to meet the needs of life science majors is no easy task.&nbsp; It requires curiosity, humility, dedication, and a willingness to be a novice learner again.&nbsp; Honestly, it may not be for everyone.&nbsp; But for those educators who are willing and able to undergo this reform, the rewards of a deep connection with life science students and pre-health professionals are immensely satisfying.&nbsp; In this talk I highlight my experiences reforming the introductory class at a former university, the resources and educators who were most influential, and the early stages of my quest to bring an IPLS class to my current college.&nbsp; Finally, I share a new podcast that I just released called Physics Alive*, where I interview PER and IPLS instructors and researchers.&nbsp; This podcast provides an opportunity for listeners to discover new ideas and even use episodes in their classrooms. *https://physicsalive.com/

Back to School: Physicists Learning the Life Sciences for IPLS

One challenge when&nbsp;teaching physics to life science students is that they do not see the connections between physics and their other coursework.. Additionally, some teachers of introductory physics believe that PER-based tools such as motion maps and energy graphs are not used&nbsp;aside of physics class and so they focus on&nbsp;algebraic problem-solving algorithms. I have found that including work from recent experimental biology in introductory physics courses can both provide relevance to bio-focused students and show physics faculty colleagues that the multiple representations used by PER informed textbook authors are used actively and effectively in current biological and biomedical contexts. Several examples from applications as diverse as bio-mechanical engineering, ethology, and molecular biology will be discussed to highlight where to look for good examples and how to incorporate such materials in introductory courses.

Mining Biological Research when Developing Curricular Materials for Introductory Physics

In the online environment, we are encouraged to find ways to assess student progress that are resistant to online cheating, and also provide an especially &nbsp;supportive environment for learning in these challenging times. &nbsp;&nbsp;Our first semester IPLS course, serving a pre-PT and exercise science population, &nbsp;focuses heavily on biomechanics.&nbsp;&nbsp; After digital practice with provided biomechanics scenarios, focusing on different aspects every week, students work on those aspects in scenarios of their own.&nbsp;&nbsp; These weekly scenario digital submissions are submitted as drafts and feedback is given in screencasts going over their work.&nbsp;&nbsp; The subsequent revisions are what is assessed for competence in the learning outcomes of the course

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