### Notes:

The Forces and Free-Body Diagrams in Circular Motion Concept Builder is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Concept Builder can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

### Teaching Ideas and Suggestions:

Many Physics courses include a unit on Circular Motion or include the topic in a unit on Newton's Laws. It is a common practice in both a Newton's Laws unit and a Circular Motion unit to conduct a force analysis. Such analyses typically begin with students identifying the forces that are present on an object in the given situation. A free-body diagram is typically drawn to represent the type, direction, and relative magnitues of the forces acting upon the object. To conduct the diagram, students need to know their force types and have a well-practiced habit of thinking about what external objects are pushing or pulling on the system or object in question. This particular Concept Builder provides students with lots of practice identifying the free-body diagram for situations involving objects moving in circles or along curved paths.

This Concept Builder was intended as an in-class activity. We recommend its use after the topic has been discussed and students have had an opportunity to practice drawing free-body diagrams. The Concept Builder includes three difficulty levels. Teachers using the Concept Builder with their classes should preview the Concept Builder (or view the Questions in the separate file) in order to judge which levels would be most appropriate for their students. Our summary of the three difficulty levels is as follows:

• Apprentice Level: Questions 1-4 Two Horizontal Circles and Two Vertical Circles
• Master Level: Questions 1-8 Two Horizontal Circles, Five Vertical Circles, and One Horizontal Circle with Angled Forces
• Wizard Level Questions 5-12 One Horizontal Circles, Four Vertical Circles, and three Horizontal Circles with Angled Forces

In order to complete a diffiiculty level, a student must correctly analyze each question for that level. If a student's analysis is incorrect, then the student will have to correctly analyze the same question twice in order to successfully complete the diffiiculty level. This approach provides the student extra practice on questions for which they exhibited difficulty. As a student progresses through a diffiiculty level, a system of stars and other indicators are used to indicate progress on the level. A star is an indicator of correctly analyzing the question. Once a star is earned, that question is removed from the que of questions to be analyzed. Each situation is color-coded with either a yellow or a red box. A red box indicates that the student has incorrectly analyzed the question and will have to correctly analyze it twice before earning a star. A yellow box is an indicator that the question must be correctly analyzed one time in order to earn a star. Once every question in an activity has been analyzed, the student earns a medal which is displayed on the Main Menu. This system of stars and medals allows a teacher to easily check-off student progress or offer credit for completing assigned activities.

The most valuable (and most overlooked) aspect of this Concept Builder is the Help Me! feature. Each question group is accompanied by a Help page that discusses the specifics of the question. This Help feature transforms the activity from a question-answering activity into a concept-building activity. The student who takes the time to use the Help pages can be transformed from a guesser to a learner and from an unsure student to a confident student. The "meat and potatoes" of the Help pages are in the section titled "How to Think About This Situation:" Students need to be encouraged by teachers to use the Help Me! button and to read this section of the page. A student that takes time to reflect upon how they are answering the question and how an expert would think about the situation can transform their naivete into expertise.

### Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Forces and Free-Body Diagrams in Circular Motion Concept Builder. These include:

• Minds On Physics Internet Modules:
The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignments CG1 through CG5 of the Circular Motion and Gravitation module provide great complements to this Concept Builder. They are best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.

Users may find that the App version of Minds On Physics works best on their devices. The App Version can be found at the Minds On Physics the App section of our website. The Circular Motion and Gravitation module can be found on Part 2 of the six-part App series. Visit Minds On Physics the App.

• Physics Interactives: Our Physics Interactives section include an interactive simulation that makes for a perfect pre-cursor to this Concept Builder. It is called Uniform Circular Motion. When combined with the accompanying activity sheet, it makes for an excellent activity to help students understand the dependence of the variables on one another for objects moving in circles.

Visit Uniform Circular Motion

Additional resources and ideas for incorporating Forces and Free-Body Diagrams in Circular Motion Concept Builder into an instructional unit on circular motion can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.