General College Physics

Wisconsin Lutheran High School

Week 12 (Oct. 28 - Nov. 1)

Reading: PSE Chap 9, Linear momentum and collisions

Topics: impulse, momentum, collisions, conservation of momentum, center of mass

Lab:

Homework Problems: These problems are due on Tuesday of Week 13. They involve conservation of momentum and center of gravity.

Perfectly inelastic collision: A 10 kg block sliding across a table is moving to the right with a speed of 5 m/s. It strikes an initially stationary block having mass 5 kg. The blocks collide, and stick together. Assume that there is no friction between the table and the sliding blocks.

What is the final speed of the blocks?
What is the speed of the center of mass immediately after the collision?
What is the speed of the center of mass just before the collision?

Perfectly elastic collision: Now consider the same collision. This time, the collision is completely elastic (that is: kinetic energy is conserved; no energy is converted into heat or sound or any other form).

What is the final speed of the blocks?
What is the speed of the center of mass immediately after the collision?
What is the speed of the center of mass just before the collision?

Optional additional Review/Practice Problems: For those of you who want additional practice. Note: I took these problems from a textbook; the answers are based on using g = 9.81 m/s^2 for the acceleration of gravity near earth (not 10 m/s^2, as we typically approximate).

A 200 gram block is pressed against a spring of force constant 1.40 kN/m until the block compresses the spring 10.0 cm. The spring rests at the bottom of a ramp inclined at 60 degrees to the horizontal. Use energy considerations to determine how far up the incline the block moves before it stops (a) if there is no friction between block and ramp (4.12 meters) and (b) if the coefficient of kinetic friction is 0.400 (3.35 meters).
A bead slides without friction around a loop-the-loop. If the bead is released from a heigh t of 3.50 R, where R is the radius of the loop, what is the speed of the bead (a) at the bottom? and (b) half-way up the loop? What is the normal force exerted by the loop (c) at the bottom and (d) half way up the loop?
A 5.0 kg block is placed on top of a 10 kg block. A horizontal force of 45 N is used to pull the 10 kg block to the right. A rope is tied between the 5 kg block and a wall on the left. The coefficient of kinetic friction between the surfaces is 0.20. (a) draw a free body diagram for each block and identify the action-reaction forces between the blocks. (b) determine the tension in the string and the acceleration of the 10 kg block (Tension = 9.80 Newtons; a = 0.580 m/s^2).
During WWI, the Prussians had a gun called Big Bertha. The shell had an initial speed of 1.70 km/s at an inclination of 55 degrees above the horizontal. Ignoring drag due to air, (a) how far away did the shell hit? (277 km) (b) How long was it in the air? (4.74 minutes) (c) what was its speed on impact?
A particle moves along the x axis according to the equation x = 2 + 3t - t^2. At t=3 seconds, find (a) the position (2.00 meters), (b) the velocity (-3.00 m/s) and (c) the acceleration of the particle (-2.00 m/s^2).

Quiz: We will have a quiz on monday of Week 13.

General College Physics

Return to course website.

Course syllabus

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 each 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.

General College Physics is a year-long introductory college-level course for advanced (typically junior or senior level) students at Wisconsin Lutheran High School. It is a dual-credit course offered at Wisconsin Lutheran High School in collaboration with Wisconsin Lutheran College. This means that students enrolled in the course have the option of receiving credit for a four-credit algebra-based laboratory science course from the College.

During the first semester, we will primarily study the science of motion and its relationship to forces. Topics include: dimensional analysis, measurement, uncertainty, estimation, dimensional analysis, 2 dimensional kinematics, projectile motion, newton’s laws of motion, force diagrams, centripetal force, circular motion, conservation of energy and momentum, torque, angular momentum, oscillations, and gravity. During the second semester, we will explore a number of inter-related topics including: heat, thermometry, the laws of thermodynamics, electricity, magnetism, optics, electromagnetic induction, radiation, atomic theory, and nuclear physics.

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!

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 on a rotating schedule in WLHS 223—the science wing on the first floor of WLHS.

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 a teaching assistants. Alyssa Ebeling is an upper-level physics major at Wisconsin Lutheran College. Here is her contact info: alyssa.ebeling[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/WLHS/

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.

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.