PHYSICS 180a, Fall 2000 Exam & Reviews

Review for Exam 3

Review of selected problems:  Wednesday December 13 @ 11:30 am in SPL59.  Email me with requests, especially of P-problems.

The third exam will be on Monday, December 18, 2000 at 2:00 PM in SPL 59.  The exam is intended to take 90 minutes. As usual, you should bring a calculator and one equation sheet (8.5'' by 11'', both sides).  Copies of the tables on the inner front and back covers of the text will be provided.

Reading covered: HRW Chapters 11-13.5, 14, & 16-18.

Topics covered:

• rotation around a fixed axis: angular variables and their relation to linear variables
• constant angular acceleration problems
• finding rotational moments of inertia
• torque; Newton's second law in angular form
• rotational kinetic energy and work done by external torques
• rolling condition and kinetic energy of a rolling object
• computing vector torque and angular momentum
• conservation of angular momentum
• equilibrium: systems including beams, blocks, ladders, cords, pulleys
• Newton's law of gravitation
• superposition and forces due to spherical shells and spheres
• gravitational potential energy
• Kepler's laws
• simple harmonic motion
• simple harmonic oscillators: springs & pendula: torsion pendulum, simple pendulum, & physical pendulum
• sinusoidal waves
• wave speed on a stretched string
• interference of waves & phasors
• standing waves: nodes, antinodes and harmonics
• sound waves, beats
• Doppler effect

• computing cross products (Sec 3-7, p. 42)
• ellipses: focus, eccentricity, semimajor axis (Fig. 14-13)

1. Begin by making a draft of your equation sheet, based on your experiences doing the problem sets (for example, you may already know you want to include something like Table 11-2).
2. Work through the "E" review under test conditions (time pressure and looking only at the equation sheet). If you find you need to look at the text or your notes, revise your equation sheet accordingly. Check your answer in the back of the book. If you have no trouble and get the right answer, move on to the next problem or section. If you get the wrong answer or are unsure about your approach, reread the related section, try one or two other odd numbered exercises (E), then try solving the same exercise again.
3. Review the problems in PS8-PS12, making sure that you now know how to solve all of them correctly.
4. Finally, test your skill by solving the problems in the ``P'' review. It is recommended that you try these under test conditions.

• 11.12E*, 11.52E*, 11.60E*
• 12.7E, 12.33E, 12.39E
• 13.12E*, 13.13E
• 14.16E*, 14.27E, 14.57E
• PS16.80*, 16.36E*, 16.46E*
• 17.4E*, 17.34E*, 17.38E*
• 18.33E, PS18.75

`P'' review

• 11.32P*, 11.65P
• 12.46P*, 12.50P*
• 13.25P, 13.29P
• 14.35P, 14.58P*
• 16.18P*, 16.53P
• 17.19P, 17.45P
• 18.7P, 18.55P

*The answers to the even numbered problems in these lists are here.

A few problem solving tips and common confusions:

• Always start by making a sketch or a sketch of a graph incorporating the given information. At the end, look at your answer and ask whether it seems reasonable.
• Virtually all Newton's law problems (e.g. Chapter 11) can be solved with the following step-by-step procedure. (1) Identify the forces acting on each object of interest and draw free body diagrams showing their magnitudes and directions. For objects that rotate (such as pulleys), also indicate the point of application in the diagram for use in computing torque. (2) Apply Newton's second law to each object. (3) Include any additional constraints, such as the equality of the magnitude of the accelerations of two objects. (4) Solve the equations.

If you want help

• Come to office hours - during reading week, Wed & Fri from 1pm to 2:30+ - others by appointment.
• Email me with problems you'd like me to discuss in the review.
• Visit the Math-Science Tutors in the colleges and Old Campus. The locations and hours of the tutors are posted at each Residential College Dean's Office.
• Work together with other students in the class.