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Circular motion changes the perception of up and down. For a skater, the need to lean in towards the centre of an arc constitutes an embodiment of centripetal acceleration. This paper presents a discussion between a physicist and a high-school science teacher without previous physics studies at university level. The discussions started as part of a course assignment and focused on a photo of skaters practicing a 'wing', which is a move in synchronised skating. The skating experiences are integrated with an understanding of the relations between radius, acceleration and the angles the total force from the ice deviates from the vertical.

Students' understanding of forces in circular motion is often incomplete. The problems are not limited to confusions about centripetal acceleration and centrifugal forces. This paper considers possible effects of different interventions by a teacher who has discovered the many types of free-body diagrams drawn by students for circular motion in a vertical plane. Students' free-body diagrams often show a lack of attention to lengths of force arrows and to the direction and size of the sum of forces. The strategies used by students may differ depending on the situation and questioning by the teacher can remind students of critical aspects they have overlooked. The revisions of responses following interventions reveal information that is not available from just a single response. This paper discusses how a matrix can be used to express the probability for revisions of responses for different teacher interventions and also help teachers decide on future interventions.

We present a case study of a conversation between ourselves and an artificial intelligence-based chatbot ChatGPT. We asked the chatbot to respond to a basic physics question that will be familiar to most physics teachers: 'A teddy bear is thrown into the air. What is its acceleration in the highest point?' The chatbot's responses, while linguistically quite advanced, were unreliable in their correctness and often full of contradictions. We then attempted to engage in Socratic dialogue with the chatbot to resolve the errors and contradictions, but with little success. We found that ChatGPT is not yet good enough to be used as a cheating tool for physics students or as a physics tutor. However, we found it quite reliable in generating incorrect responses on which physics teachers could train assessment of student responses.

This paper presents preparations, execution and reflection on results for the physics part of a CSI task for the European Union Science Olympiad 2010, taking place at the University of Gothenburg. The participants were required to make a graph of the cooling of a swede ("Brassica napus"), as a proxy for the cooling of a murder victim, and to choose a mathematical expression for the cooling curve, as well as assigning an approximate time of death

Take a selection of balls and marbles along to a nearby playground slide and let students investigate factors that may influence how balls accelerate down an inclined plane. Students can make hypotheses in small groups, plan investigations to test multiple possible explanations and draw conclusions about the importance of different variables. The experiments illustrate the principle of equivalence between inertial and gravitational mass, as well as of the importance of mass distribution. Students can develop an intuitive feeling for these concepts even without dealing with the full mathematical treatment, which involves torque, angular momentum and moment of inertia, typically treated in high-school or introductory university physics courses. The paper discusses this investigation as part of a setup of teacher professional development events on a playground.

Changing acceleration and forces are part of the excitement of a roller coaster ride. According to Newton's second law, F = "m"a, every part of our body must be exposed to a force to accelerate. Since our bodies are not symmetric, the direction of the force matters, and must be accounted for by ride designers. An additional complication is that not all parts of the body accelerate in the same way when the acceleration is changing, i.e. when there is jerk. Softer parts of the body provide varying levels of damping, and different parts of the body have different frequency responses and different resonance frequencies that should be avoided or reduced by the roller coaster designer. This paper discusses the effect of acceleration, jerk, snap and vibration on the experience and safety of roller coaster rides, using authentic data from a dive coaster as an example.

Is a suction cup at the bottom of a bathtub subject to an upward force from the surrounding water, even if there is no water under it? A student question, posted in a teacher facebook group on a Monday morning, led to a discussion involving 21 comments with 225 replies offered by 16 teachers during the next few days, including several simple experiments, as well as modeling, to evaluate different arguments. The discussions, summarized in this paper, provide an example of how social media can provide an 'extended teacher room' where teachers can explore and refine their understanding in a safe and mostly supportive environment, and also find ways to give more elaborate answers to challenging student questions.

Large drop towers let you experience a couple of seconds of nearly free fall before stopping gracefully in magnetic brakes or bouncing a number of times on compressed air, as in the Turbo Drop tower considered in this work, where many complementary representations are used. An accelerometer taken along on the ride captured the forces experienced by the body, and a pressure sensor provided a simultaneous proxy measurement of elevation. These data can be treated numerically: integration of the accelerometer data gives a velocity graph which can be compared to derivatives of the elevation data obtained from the pressure sensor. Plotting elevation versus velocity gives a phase portrait for the damped oscillations of the gondola before it comes to a stop. These abstract mathematical and graphical representations are complemented by screen shots from a video as well as from a virtual reality movie offering the view from the point of a rider. Forces and acceleration overlaid in a 2D version of the VR movie give a geometric illustration of Newton's second law, in addition to the mathematical treatment. This work thus provides a wide range of representations, aimed to support student representational fluency and conceptual understanding of important force and motion concepts.

Students often use incoherent strategies in their problem solving involving force and motion, as revealed, e.g. when they are asked to draw force diagrams for amusement rides involving circular motion, whether in horizontal or vertical planes. Depending on the questions asked, assignments involving circular motion can reveal different types of more or less correct and coherent strategies used by the students. This paper presents a number of different assignments involving circular motion. Alternative drawings, as found in student responses, are presented as a support for teachers to discern the strategies--an educational discernment. In addition, different strategies and examples used by textbooks concerning free-body diagrams and acceleration are discussed, as well as degrees of abstraction and realism.

This article describes the development and deployment of Physics Toolbox Play, a gamified component of the "Android Physics Toolbox Sensor Suite" app, that can introduce young children through adults to fundamental physics principles. The app was used successfully in a variety of contexts, including STEM fairs with primary and secondary students and workshops with undergraduate physics majors and practicing teachers. Anecdotes from our experiences suggest that smartphones are an effective way to introduce learners to the big ideas and big principles in physics.

Your body is not a point particle. The nature and direction of the forces counteracting gravity influence your experience of uniform rectilinear motion--as does your own orientation in relation to the force of gravity. Sensors in smartphones or other devices can capture these forces, and help establish a connection between the personal experience of motion and the textbook description of forces acting on inanimate objects. This work focuses on authentic examples of uniform or nearly uniform rectilinear motion in escalators and roller coasters. Multiple complementary representations of the motion are presented, including photos, graphs of accelerometer, gyroscope and barometer data, mathematical expressions, free-body diagrams and video analysis, including screenshots. The paper aims to inspire teachers to use a larger repertoire with more variation in the examples illustrating uniform rectilinear motion. Analysing these relatively simple motions lays a good foundation for the interpretation of data from more complicated motions.

A small group of interested upper secondary education students participated in a workshop where they created a particle-based physics engine and used the engine to implement a hanging cloth simulation and a two-dimensional heat diffusion model of their own creation. During the implementation of their models, learning opportunities present themselves in the form of opening up and exploring different dimensions of variation for the students. By varying aspects and discerning how these changes affect the program, students can construct meaning about the system. The students were video and audio recorded during the workshop and interviewed afterwards. Based on the transcripts, students use of programming was analyzed using social semiotics and variation theory of learning with a focus on the three aspects: coding, visualization, and interaction. The analysis identifies usages of programming such as a transductive link between semiotic systems, the ease of varying and iterating aspects, and the ability to enter into a loop of discovery and understanding.

Describing the motion in a vertical roller coaster loop requires a good understanding of Newton's laws, vectors and energy transformation. This paper describes how first-year students try to make sense of force and acceleration in this example of non-uniform circular motion, which was part of a written exam. In addition to an analysis of the exam solutions by about 60 students, a group interview was performed a couple of weeks later with four students, who had all passed the exam. The interview allowed the students to reflect on assumptions made and information missed.

Most of the physics (as well as the other sciences) taught in school can be described as well-established or consensus science. This is the kind of science knowledge that was mostly developed over a century ago. The inclusion of contemporary science research in compulsory school science teaching could be justified from a variety of reasons: increasing students' interest and motivation; providing insights into modern research practice; and as a frame for teaching nature of science (NOS) perspectives. The present article focuses on the latter--contemporary science as a means to teach NOS. The article builds on data from an in-service teacher training course that focused on ways to include contemporary science in lower secondary physics education. Each course participant chose a research area, interviewed a scientist, and wrote a popular science article based on the interview. The article was written with secondary students (13-15 years old) as a target audience. By the end of the course the participants designed, implemented and evaluated a teaching unit which was based on the popular science article. The present article analyses what NOS perspectives that have been included in the popular science articles. The results show a high diversity of NOS aspects, which indicate a great potential for taking contemporary science research as a starting point for NOS teaching.

It has long been argued that nature of science (NOS) is an important part of science teaching. In the literature, many different approaches to NOS have been suggested. This article focuses on a storytelling approach, and builds on data from audio recordings from three middle-school (school year 6) classrooms. The three science classes are run by three science teachers who have been introduced to NOS and storytelling during a one-day workshop. These three teachers chose to tell the students a story about Ernest Rutherford. The stories told by the teachers, as well as the whole-class discussions afterwards, are analysed with respect to what NOS aspects were communicated. The results show that many different NOS aspects, such as the tentative nature of scientific models, empirical aspects of the scientific knowledge process, as well as human aspects of science, emerge in the context of the story about Rutherford and his work on the atomic model. The results indicate promising possibilities for storytelling as an approach to NOS teaching.

Vertical amusement rides let your body experience the tickling sensation of feeling light, but also feeling much heavier than as usual, due to velocity changes as you move up and down. Family rides offer different possibilities to visualize the forces that are experienced by your accelerating body. This paper presents a number of different ways to view and experience the motion in a small vertical amusement ride. A smartphone includes an accelerometer that can provide a graph of the forces acting during the ride. A movie from the smartphone camera lets students recall the motion which can then be analysed in more detail. The complementary representations may help students develop a deeper understanding of the relation between force and motion. The affordances of these different semiotic resources are analysed in some detail. In addition, we discuss responses from a number of students to questions about where you feel light and where you feel heavy. We find that the experience of the body is an underused resource in physics teaching.

An amusement park is full of examples that can be made into challenging problems for students, combining mathematical modelling with video analysis, as well as measurements in the rides. Traditional amusement ride related textbook problems include free-fall, circular motion, pendula and energy conservation in roller coasters, where the moving bodies are typically considered point-like. However, an amusement park can offer many more examples that are useful in physics and engineering education, many of them with strong mathematical content. This paper analyses forces on riders in a large rotating pendulum ride, where the Coriolis effect is sufficiently large to be visible in accelerometer data from the rides and leads to different ride experiences in different positions.

Free fall is commonly discussed as an example of the equivalence principle, in the context of a homogeneous gravitational field, which is a reasonable approximation for small test masses falling moderate distances. Newton's law of gravity provides a generalisation to larger distances, and also brings in an inhomogeneity in the gravitational field. In addition, Newton's third law of action and reaction causes the Earth to accelerate towards the falling object, bringing in a mass dependence in the time required for an object to reach ground--in spite of the equivalence between inertial and gravitational mass. These aspects are rarely discussed in textbooks when the motion of everyday objects are discussed. Although these effects are extremely small, it may still be important for teachers to make assumptions and approximations explicit, to be aware of small corrections, and also to be prepared to estimate their size. Even if the corrections are not part of regular teaching, some students may reflect on them, and their questions deserve to be taken seriously.

Trampolines can be found in many gardens and also in some playgrounds. They offer an easily accessible vertical motion that includes free fall. In this work, the motion on a trampoline is modelled by assuming a linear relation between force and deflection, giving harmonic oscillations for small amplitudes. An expression for the cycle-time is obtained in terms of maximum normalized force from the trampoline and the harmonic frequency. A simple expression is obtained for the ratio between air-time and harmonic period, and the maximum g-factor. The results are compared to experimental results, including accelerometer data showing 7g during bounces on a small trampoline in an amusement park play area. Similar results are obtained on a larger garden trampoline, and even larger accelerations have been measured for gymnastic trampolines.

Comparing two objects falling together is a small-scale version of Galileo's classical experiment, demonstrating the equivalence between gravitational and inertial mass. We present here investigations by a group of ten-year-olds, who used iPads to record the drops. The movie recordings were essential in the follow-up discussions, enabling the students to compare the different situations and to discern situations where air resistance was essential and where it could be neglected. By considering a number of familiar situations and simple investigations that can be performed, e.g., on a playground, students may come closer to an appreciation of the deep significance of the non-influence of mass on motion under gravity.

Friction is an important phenomenon in everyday life. All children are familiar with playground slides, which may thus be a good starting point for investigating friction. Motion on an inclined plane is a standard physics example. This paper presents an investigation of friction by a group of 11-year olds. How did they plan their investigations? What aspects of friction could they discern? What understanding of the nature of science was revealed--and developed--during their investigation and subsequent discussion with the teacher?

A roller coaster ride comes to an end. Magnets on the train induce eddy currents in the braking fins, giving a smooth rise in braking force as the remaining kinetic energy is absorbed by the brakes and converted to thermal energy. In this paper an IR camera was used to monitor the temperature of the first braking fin, before, during and after the passage of a train. In addition, the resulting acceleration of the train was modelled and compared to accelerometer data for the Kanonen roller coaster in Liseberg. The results were used to model the distribution of temperature increase over the braking fins. Finally, the cooling of the fins after the passage of the train was analysed and compared to the IR data. (Contains 7 figures and 5 footnotes.)

Many modern cell phones have built-in sensors that may be used as a resource for physics education. Amusement rides offer examples of many different types of motion, where the acceleration leads to forces experienced throughout the body. A comoving 3D-accelerometer gives an electronic measurement of the varying forces acting on the rider, but a complete description of a motion also requires measurement of the rotation around the three axes, as provided, for example, by the iPhone 4. Here we present and interpret accelerometer and gyroscope data that were collected on a rotary pendulum ride. (Contains 8 figures.)

During a roller coaster ride, the body experiences acceleration in three dimensions. An accelerometer can measure and provide a graph of the forces on the body during different parts of a ride. To couple the experience of the body to pictures of the ride and an analysis of data can contribute to a deeper understanding of Newton's laws. This article considers the physics of launched roller coasters. Measurements were performed with a three-dimensional co-moving accelerometer. An analysis is presented of the forces in the different ride elements of the Kanonen in Goteborg and the Speed Monster in Oslo, which both include loops and offer rich examples of force and acceleration in all dimensions. (Contains 12 figures and 1 footnote.)