Physics 160 Homepage
Preliminary final grades are here. Your code is the same as for Test 3. The class average score for all three tests and the homework (weighted using the coefficients listed below) was 71%. If you elect not to take the final exam on Dec. 12, this preliminary grade will be your final course grade. If you take the final exam, your grade will be re-calculated based on the best three of four tests. The grading scale shown will not be adjusted, so taking the final exam cannot hurt your grade, it can only improve it. Using the posted grades, you can determine what score you'll need on the final exam to change your preliminary grade.
Instructor: Dr. Michael Hasselbeck
Office: Physics & Astronomy Rm. 153 Phone: 277-0590 email: mph@as.unm.edu
To see me in my office, please make an appointment (call or email).
Class meeting times: Tuesdays & Thursdays, 5:30 - 6:45 pm; Regener Hall 103
Textbook: Fundamentals of Physics by Halliday, Resnick, & Walker. The course will cover Chapters 1-16, with the exception of Chapter 13 (Engineering majors will encounter Equilibrium and Elasticity in their required mechanics course).
Pre-requisites: Math skills are essential! You are expected to have a solid foundation in algebra, geometry, and trigonometry. If you have already taken a semester of calculus, you'll be in excellent shape. If not, you should be taking calculus concurrently. Calculus is the special weapon for tackling mechanics problems (Issac Newton invented calculus for exactly this purpose!). Much of the necessary calculus will be developed as needed during the semester, but realize this is not a calculus course. If your high school math skills are lacking or rusty, be prepared to study extra-hard or you'll be getting lost and eventually left behind.
Assignments: Homework problem sets will be assigned on a regular basis throughout the semester, at least one set per week. It is anticipated that the homework will be handled almost entirely via the web. High speed web access is available in various computer pods located around campus. The due dates and times as well as complete solutions can be found on this website. Your lowest three homework scores will be dropped when computing your overall homework score. Click here to go to the assignments page.
Tests: There will be three in-class, closed-book tests at regular intervals during the semester and a comprehensive final exam at the end. Each test counts for 30% of the final grade, including the final exam. Only the scores from your best THREE tests will count to the final grade - the lowest of the four test scores will be dropped. There will be no make-up tests! If you miss one of the tests, for whatever reason, this will count as your dropped test. If you miss a second test, this will be scored zero and averaged into your grade. Please realize that there will be no make-up tests under any circumstances. You are free to skip any exam as you so desire, including the final. Your best three test scores carry the same weight in determining your final grade.
Tentative Test Dates (subject to change): September 17, October 22, November 26. Last day to drop courses is September 27. Final exam is December 12 from 5:30-7:30 pm.
Grading: The final grade is weighted as follows: the best three tests (out of three mid-terms and a final) count 30% each, and homework is 10%. Scores will be curved to reflect the difficulty of the tests when determining the final grades.
Classroom Etiquette: No attendance will be taken. If you need to discuss something with a classmate during lecture time, please do so outside the lecture hall. Turn off the cellphones. If you arrive late, please make an extra effort not to disturb a lecture in progress.
Cheating: You are encouraged to work together to solve the homework problems. That's what I did when I took this course a long, long time ago and it helped me immensely. All collaboration, however, must end at test time. If you get caught cheating on a test, rest assured you'll wish you didn't! I'm convinced it's smarter and safer to invest the energy and effort in studying rather than conjuring up clever ways to cheat. Even if successful, you are only delaying the inevitable -- the skills learned in this course will be the foundation for the upper level courses that you'll eventually need to pass to get your degree. Even if you think you can cheat your way through your whole college career, I can guarantee you'll be "discovered" early in your first professional position out in the real world. If you find it necessary to cheat to pass this class, you shouldn't be here in the first place.
How to pass this class: Understanding how to do the homework problems is the key to passing this course. If you can solve the homework problems, you should have little trouble with the tests. Work through the examples in the textbook. That means putting your pencil to the paper - not just skimming over words in the book. There will be no "trick" questions on the tests -- the test questions will look a lot like the homework problems and examples. Although I'd like to think I can explain things well enough that you'll understand everything first time in the lecture, that's highly unlikely to happen. Ask questions. You learn the physics by sweating through the problems and examples, making lots of mistakes, getting hopelessly stuck at times, and even experiencing profound frustration. This is a hard course and it goes with the territory. There are a fortunate few with natural talent for learning this stuff quickly (I am not one of those lucky people), but most students of introductory physics need many, many hours per week to successfully handle this course. You should allocate plenty of time to do the assignments, at a time when you are alert with no distractions. Setting aside one hour before the football game to do your physics homework is not a good idea. If you can't devote the necessary time, you shouldn't be taking this course. I'd like to see everybody succeed, but that's only possible if you can make the commitment and put in the time. And the reward for all this hard work is not simply passing this course -- you'll have developed the problem solving skills, work ethic, and discipline that will serve you well for the rest of your college and professional career.
Test 3 was given on Tuesday, November 26 covering Chapters 9-12, 14-16. Closed book, closed notes, calculators permitted. Results, scores, solutions are here.
Test 2 was held on Tuesday, October 22 covering Chapters 5-8. Closed book, closed notes, calculators permitted. Scores and solutions are here.
Test 1 was Tuesday, September 17 on Chapters 1-4 of the textbook. Closed book, closed notes. Calculators permitted. Results, scores, and answers are here.
The sport of drag racing is where the physics of linear motion is put into practice. This Funny Car driven by Del Worsham burns a mixture of nitromethane and methanol to create more than 6000 horsepower. It can accelerate from a standing start to 320+ mph in a distance of 1/4 mile (402 m) in a time of about 4.75 s. In class, we determined that a Funny Car accelerates at nearly 5g in the first 20 m of a race. Other physical principles in play here are aerodynamics and friction. In the photo, the driver is deliberately "burning rubber" prior to a run to heat the rear tires, thus increasing the coefficient of friction between the tires and pavement.
Freestyle motorcycle rider Chris Brock uses a ramp to generate a vertical component of velocity that gets him airborne. This type of motion (stunts notwithstanding) is readily analyzed using vector components in the horizontal and vertical directions. We showed that a motorcycle can clear 80 feet (24.4 m) by launching off a 45 degree ramp at a minimum speed of 35 mph (15.5 m/s).
Rockets provide an excellent example of Newton's third law of motion in action. The downward force of thrust gives rise to an equal and opposite force of lift that overcomes the force of gravity. Photo courtesy of the Albuquerque Rocket Society.
These skydivers attain a terminal velocity of about 120 mph by orienting their bodies perpendicular to the ground to maximize the cross-sectional area during free-fall. A speed skydiver on the other hand, deliberately attempts to reach free-fall speeds in excess of 300 mph by minimizing his aerodynamic cross section.
This motorcycle crash sequence (Frame 1, Frame 2) illustrates the dissipation of kinetic energy by friction. For the fallen rider to come to rest, his kinetic energy must be transfered to heat at the interface of his leather suit with the pavement and gravel. Friction accomplishes this by doing negative work. Note the much higher kinetic energy of the motorcycle due to its larger mass. The crash was caused by a false neutral that occured during a gear change, which upset the balance of forces in a high speed turn. The rider was unhurt. The motorcycle wasn't.
From the perspective of a fixed observer, a rolling wheel moves faster at its highest point compared to where it makes contact with a surface. Observe the front wheel of this time trial bicycle ridden by 1998 Tour de France winner Marco Pantani. The top spokes are moving faster than the camera shutter speed can capture.
By delicately balancing the torques, factory Kawasaki superbike rider Eric Bostrom maximizes his cornering speed. There are two components of torque about the tire: 1) gravity (pointed out of photo plane) and 2) centripetal force (pointed into plane of photo). The dot indicates the approximate center of mass and R is the radius of the corner on the racetrack. By hanging his body far off the motorcycle, he lowers the center of mass thus decreasing the angle between the position vector and the centripetal force vector -- reducing this component of torque. Minimizing this angle allows him to ride through the corner at maximum velocity (v) while still keeping the two components of torque in balance.
Results of the math quiz given on the first day of class are here.
