Circular Motion  Physics  Gravity Course (Class 4)
Edouard RENY, Music Producer & Tutor in Physics


1. What is an Angle? + Introduction to Circular Motion
3:28 
2. Angular Velocity
3:05 
3. Centripetal Acceleration
5:45 
4. Centripetal Force
2:46 
5. Circular Motion: Solved Example
4:54 
6. Training Exercise 1 (Easy)
5:00 
7. Training Exercise 2 (Easy)
2:34 
8. Training Exercise 3 (Moderate)
6:03 
9. Training Exercise 4 (Difficult)
9:13

About This Class
Circular Motion principles appear in many areas of Physics: for example in mechanics, Atomic Physics, magnetism, particle physics , gravitation etc… This is why it is essential to understand this concept well.
By taking this class, you will gain an understanding of all the fundamentals related to circular motion. This knowledge will allow you to solve many problems in physics: Using the mathematical consequences of a motion which is circular allows to derive many useful relations between quantities, and in the end, easily solve problems that otherwise would appear very difficult.
In videos 1 through 4, we discuss the various quantities to consider when dealing with a system in circular motion: angles, angular velocity, centripetal acceleration and centripetal force. We also lay down proofs of the relations between these quantities.
Video 5 is an application example: we use principles of circular motion to determine the kinetic energy of an electron in orbit around a proton (a hydrogen atom).
In Video 6 through 9, it is your turn: each video presents an exercise for you to work on, followed by a detailed correction on the board. Videos 6 and 7 are straight forward applications of the formulas. Video 8 requires a little more reflection, and video 9 is challenging.
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Content of the class
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Video 4.1: Introduction + Lesson  What is an angle?
Video 4.2: Lesson  Angular Velocity
Video 4.3: Lesson  Centripetal Acceleration
Video 4.4: Lesson  Centripetal Force
Video 4.5: Application example: The kinetic energy of the electron in a hydrogen atom
Video 4.6: Training Exercise 1 (Easy)
Video 4.7: Training Exercise 2 (Easy)
Video 4.8: Training Exercise 3 (moderate difficulty)
Video 4.9: Training Exercise 3 (challenging)
All 4 training exercises are provided as pdf files and formatted so that you can print the exercise and work on them away from the computer. Answers are provided also in a pdf document.
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This class is part of a larger course named “Gravity, The Basics”.
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“Gravity, The Basics” explores the elementary notions of Newtonian gravity.
Class 1: “Linear Motion” (because being comfortable with this notion will allow you to make the most of the full course). This class presents a stepbystep technique to solve all motion problems when the acceleration is constant. This class can be taken by itself.
Class 2: “Newton’s Universal Law of Gravitation”, which you can be seen as a doorway to the deeper dive we carry out in the next classes.
Class 3: “Gravitational Fields”, the core of this course: This class teaches first what is a field, and then dives into a deep description of gravitational fields, gravitational field strength and gravitational field lines. It is packed with many exercises aimed at making the student comfortable with these notions.
Class 4: “Circular Motion”, prepares you for the section on orbital motion. You are presented with a detailed explanation of fundamental quantities that occur in circular motion (angles, angular velocity, centripetal acceleration and forces). This class can be taken by itself.
Class 5: “Orbital Motion”, for you to master the motion of planets around their star: This class blends notions taught in class 3 (gravitational fields) with notions presented in class 4 (circular motion), in order to get a good grasp of what is an orbit, and how to manipulate easily orbital motion concepts.
Class 6: “Wrappingup and Gravity Quiz”. Once you have viewed all 5 classes, it’s time for the exam! After a 5minute summary of all notions presented in “Gravity, The Basics”, 12 examlike questions are presented and corrected in detail.
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Level of this class
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This class is suited for end high school and entry level University students taking Physics. Any person interested in Physics and in need of a refresher about circular motion will also enjoy this class.