## Teacher Notes for Circular and Satellite Motion

### Unit Overview

We estimate this to be a 13-day unit if you address all the Learning Outcomes. An additional day should be added for an exam. There are three primary goals for the unit:

1. To develop the understanding and skill to analyze an object moving in a horizontal or vertical circle, to represent the relative magnitude and direction of the individual forces acting upon the object using a free-body diagram, and to relate the force values to circular motion parameters such as the object mass, the object speed, the turning radius, the period, etc.
2. To explain the concept and mathematics of universal gravitation and gravitational field strength.
3. To explain the concepts associated with satellite motion and to apply circular motion mathematics to the motion of satellites in order to generate and use orbital motion equations.

Our Lesson Plans and Pacing Guide allocate six days to the first goal. The remaining seven days are devoted to understanding universal gravitation and satellite motion (and a day for review).

### Time, Content, and Decisions

When it comes to planning all the Physics you wish to teach your students, time is more often the enemy than the friend. While it is difficult for us to imagine cutting out a unit on circular motion, gravitation, and satellite motion, we recognize that for many teachers it is one of the first topics to receive the proverbial axe. But before you decide that this topic doesn't make the cut because of a shortage of time, ask yourself: will I be taking my class on an amusement park physics field trip in the Spring semester. So much of the first half of this unit will be essential if you are planning on such a field trip. And much of our treatment of the physics of moving in circles is tied to roller coasters and amusement park rides.

You're not likely to get that field trip to the moon approved by the administration. So, you're likely to think the second half of the unit can easily be discarded. But before you do, you should know that there are students in you class whose interest will be piqued by the topics of the second half of the unit in a manner that no other topic will do so. We realize we don't have a vote in this matter. And as we've said elsewhere, The Physics Classroom has never held any teacher at gunpoint with the demand that they cover all our topics. It's 100% your decision.

### Physics Interactives

We included six Physics Interactives simulations in our Lesson Plans. But since we have more than a dozen simulations in this section, we didn't include them all. You might find one that we didn't assign to be more fitting for your class than one that we did assign. It's worth your time to pay a visit to the Circular and Satellite Motion page of our Physics Interactives.

### Project Time

Looking for a project? You will find two ready-to-use ideas in our Physics Interactives section. Check out ...

1. Barrel Ride
Students experiment with the parameters associated with the design of a barrel ride (sometimes referred to as a rotor ride). They modify the barrel radius, the period of its spin, and the mass of a rider and observe the effect upon the experience, Values of speed, acceleration, forces, and the number of Gs are provided. A thrill and safety report is also provided. The goal is to design a ride that is both thrilling and safe. A Student Activity sheet is available.
2. Roller Coaster Design
Students investigate the effect of design parameters upon the safety and thrill of a roller coaster ride. Modify the height and radius of curvature of loops and hills and investigate the effect of such changes upon the rider's experience. A Student Activity sheet is available.

The Circular Motion and Gravitation section of our Calculator Pad includes 18 problem sets with well over 100 problems. We used this bank of problems to create six custom CalcPad problem sets for the Algebra-Based Physics course. But if you need more problems, you will find them among these 18 problem sets. And with a Task Tracker subscription and our directions and video walk-through, you can even create your own custom problem sets or edit one of ours.

### Science Reasoning Center

The Circular Motion section of our Science Reasoning Center is loaded with activities. Some have a strong NGSS alignment. All have some NGSS alignment. And all would be worthy activities for any Physics curriculum, whether NGSS aligned or not. These activities provide a slightly different approach than Concept Builders or Minds On Physics. They tend to de-emphasize  conceptual development and emphasize scientific processing, data interpretation, experimental analysis, etc. in the context of a Physics topic. They often make great follow-ups to labs and can sometimes be used as an introduction to a topic. Check out a few of our favorites:

1. Weightlessness Training
After reading a short passage about NASA astronaut training, students interpret a graph and a diagram in light of a body of text, select data values from a graph, identify conclusions that are consistent with a model, and translate information from one graph to another graph.
2. Roller Coaster Loops
Students use presented data for roller coaster loop designs in order to identify the effect of one variable upon another variable, to compare data points from different tables, to interpolate and to extrapolate from data in a table, to draw conclusions that are consistent with the provided data, and to use provided data to evaluate the safety issues surrounding projected loop designs.
3. Universal Gravitation
This three-part NGSS-inspired activity includes a paragraph completion activity and two computational activities in which students investigate the effect of mass or distance upon the gravitational force.
4. Kepler's Laws
Students complete two activities by answering multiple choice questions that focus on the various representations of the distance-speed-time relationship for an orbiting satellite or planet. Students use Kepler's third law to predict the values of period or radius when a change is made in the other quantity. And finally, students complete an explanation of the qualitative patterns in distance, speed and time for an orbiting planet.

If you have a Task Tracker subscription, visit the Teacher Resources section in order to quickly preview the activity and navigate through all the questions.

### Other Resources

There are several resources that we did not list in our Lesson Plans or Learning Outcomes and Activities that you may find to be very helpful. These include:

1. Physics Interactives: Vertical Motion Simulator
Students explore the motion of a ball on a string moving in a vertical circle. The simulation is accompanied by a Student Activity sheet and a Concept Checker.
2. Physics Interactives: Barrel Ride
Students modify the parameters that influence the thrill and safety of the ride.
3. Physics Interactives: The Value of g
This Interactive allows a student to explore how g varies with location around the globe. The challenge is to see if you can find the pattern.
4. Concept Builder: Case Studies - Circular Motion
Students compare the velocity, acceleration, and net force of two different objects moving in circles with different radii, periods, speeds, and mass.

### Also Available ...

Physics teachers may find the following for-sale tools to be useful supplements to our Lesson Plan and Pacing Guide section:

1. Task Tracker Subscription (annual purchase)
A subscription allows teachers to set up classes, add students, customize online assignments, view student progress/scores, and export student scores. Task Tracker accounts allow your students to begin assignments in class or at school and to finish them at home. View our Seat and Cost Calculator for pricing details.

2. The Solutions Guide
We publish a free curriculum with >200 ready-to-use Think Sheets for developing physics concepts. The Solutions Guide is a download containing the source documents, PDFs of source documents, and answers/solutions in MS Word and PDF format. An expanded license agreement is included with the purchase. (Cost: \$25 download)

3. Teacher Presentation Pack
This is a large collection of downloadable content packed with nearly 190 Microsoft PowerPoint slide decks, the corresponding Lesson Notes (as PDF and fully-modifiable MS Word format), about 170 animations (in .gif, .png, and .mp4 file formats), a countless number of ready-to-use images (including the original source documents that would allow for easy modification of those images), and a license that allows teachers to modify and use all the content with their classes on password-protected sites (such as course management systems).  (Cost: \$40 download)

4. Question Bank
We distribute a Question Bank that includes more than 9300 questions neatly organized according to topic. The Question Bank is the perfect tool for busy teachers or new teachers. Even if you don't use the website with your classes, the Question Bank will assist you in quickly putting together quizzes, tests and other documents with high-quality questions that target student's conceptions of physics principles. And if you do use The Physics Classroom website, the Question Bank is the perfect complement to the materials found at the website. (Cost: \$25 download)