General College Physics

Wisconsin Lutheran High School

Week 13

Reading: PSE Chap 10, Rotation of a rigid body about a fixed axis

Topics: angular velocity, angular acceleration, rotational kinematics

Lab:

Homework Problems: Due Tuesday , Nov. 14 at noon.

Rotating record player problem: Consider a record player. The record, in the form of a disk, spins at a rate of 33 revolutions per minute. A small bug of mass m = 1 gram is located 10 cm from the axle; it clings tenaciously to the record as it spins.

What is the period of revolution, T, of the record, in seconds.
What is the frequency of revolutions, f, in Hz.
What is the angular speed, omega, in radians per second.
If, at time t = 0, the bug is located at an angle theta = 0, then through what angle has the bug moved in one second? Report this in both radians and in degrees.
Is the bug accelerating as it clings to the record player? If so, then what is the magnitude and direction of the acceleration?

Slowing record player problem: Suppose now that the record player to which the bug is clinging, which is initially turning at 33 rpm, is turned off. It decelerates at a constant rate until it comes to a stop 10 seconds later.

What is the angular deceleration, alpha, of the record player (in radians per second squared)?
Make a plot of the angular speed as a function of time. Appropriately label your plot.
What is the angular speed, omega (in radians per second), of the record player at t = 5 seconds?
What is the speed of the bug at this moment in time?
What is the acceleration of the bug at this moment in time? In particular, what are the magnitude and directions of both the centripetal and tangential acceleration of the bug at this moment?
What is the magnitude of the frictional force acting on the bug at this moment?

Quiz: Monday, Nov. 6. Covering conservation of energy and momentum.

General College Physics

Return to course website.

Course syllabus

Physics: The world around us is in a state of constant change: the sun and moon rise and set, waves crash, mists rise, rain falls, fires burn, rocks form, and mountains crumble. Amidst all of these changes, there are certain patterns; there is a discernible order. In other words: the stars, the seas, the clouds, the rocks, and the earth itself each seem to have a particular nature. Physics is the careful study of the natures of things. In fact, the word physics literally means "natures" in the Greek language.

Course overview: General College Physics is a year-long introductory course for advanced (typically junior or senior level) students at Wisconsin Lutheran High School who want to better understand the natures of the things we see around us. It is a dual-credit course offered at Wisconsin Lutheran High School in collaboration with Wisconsin Lutheran College. For a detailed overview of the topics we will be covering, refer to the course website (www.greatphysics.com) and the tentative calendar on the following page. Emphasis on theoretical topics, careful thinking, laboratory experiments, and problem solving makes this course challenging. My aim is to help you succeed in this course, and to have fun while learning physics. So please do not hesitate to contact me with any problems you may run into this semester!

Advanced Placement credit: While this is not designated as an AP course, students students have successfully taken the AP Physics test at the end of the year for college credit.

Course textbook: The course will be organized around a book: the Pocket Guide to accompany Physics for Scientists and Engineers (4th edition) by Serway. (I’ll call this PSE for short.) I would highly recommend obtaining a copy of this book. It is inexpensive, compact, and well-written. It will make a very handy addition to your home science library. If you don't want to buy it, I will have copies to loan out for the semester.

Course time and location: The course meets every day (Monday through Friday) during the academic year from 2:16 until 3 pm in WLHS 223—in the science wing on the first floor of WLHS. On late start days (such as Wednesdays) the course begins at 2:24.

Professor: Dr. Kuehn from Wisconsin Lutheran College (WLC) is the professor for this course. Contact info: kerry.kuehn[at]wlhs.org

Teaching Assistant contact info: The Wednesday course sections (beginning in September) will be overseen by two teaching assistants. Alyssa Ebeling and Zeke Micheel are upper-level physics majors from Wisconsin Lutheran College. Here is their contact info: alyssa.ebeling[at]wlc.edu, ezekiel.micheel[at]wlc.edu

Course websites: In addition to the course information provided through WLHS’s OnCampus system, we will be also using a website I’ve designed for this course: www.greatphysics.com/WLHS1/

Homework exercises: I will assign weekly homework problems. These are designed to deepen your understanding of lecture material and to prepare you for the quizzes and tests. I do not intend to grade your homework solutions; I will merely give you credit for handing in your best attempt by the due date. Please refer to the late work policy for more details.

Laboratory exercises: Some of our weekly assignments will include laboratory work. Labs will typically take up at least two class periods. Your laboratory notebook pages must be submitted by the assigned due date. More details about the required format and expectations will be discussed before the first laboratory period. You will need to order/purchase a dedicated laboratory notebook. Here are guildlines on what to include in your laboratory notebook.

Quizzes: We will have in-class quizzes almost every week on Monday. To prepare for quizzes, you should read the assigned book chapter (at least once), review the lecture material, complete all of the homework problems, and review the homework solutions.

Tests: We will have a midterm exam before the end of the first (and third) quarters and a comprehensive final examination before the end of the second (and fourth) quarters.

Software: Logger Pro 3.15 Is an excellent data analysis software package. Download for Wndows 10, 8.1, 7, and for macOS 10.14, 10.13, 10.12, 10.11, 10.10. For more details on how to download and install Logger Pro click here.