The Mechanics Section of PHY138Y

Mechanics is the study of the effects of energy and forces on the motion of physical objects. This document discusses the curriculum of the Mechanics Section of PHY138, and then provides access to summaries of the individual classes.

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Chapter Include/Skip
All is included. However §1.6 - Significant Figures will be discussed as part of our special class on errors. We will talk about §1.10 - Modeling, etc. in the context of later classes, not as a separate topic.
Skip §2.8
Skip §3.7
Skip §4.8
Only include §5.2, §5.6 and §5.7
Skip §6.7 and §6.9
Skip §7.8
Skip §8.5, §8.6 and §8.7

Skip §10.10, §10.11 and §10.12. Note that our use of translation/rotational analogs means that our discussion sometimes has little connection to the textbook's approach. This is particularly true for §10.6 and §10.7. We did talk about the two crucial results of those two sections, however.

  1. In equilibrium the total external torque is equal to zero.
  2. The torque is the moment of inertia times the angular acceleration.


Unless explicitly stated otherwise, material not discussed in class will not be the subject of questions on the tests or the exam.

Applications of the Physics in the above curriculum to LIfe Sciences applications are part of the curriculum, and may be examinable.

Beginning in Chapter 6 (§6.4 - Work Done by a Varying Force), the text begins using integrals as a way of expressing the sum of rectangular areas under a curve in the limit as the width of each individual rectangle goes zero.This is just a statement of the area under the curve in the language of mathematics and the integral sign shown to the right is just a stylized letter S for sum. However, we will not expect you to know how to do the mathematical manipulations of integration until your math course teaches it: for MAT135 this is scheduled to begin just before the Christmas break.

integral sign

Class Summaries

The remainder of this page provides access to summaries of the material discussed in our lectures on mechanics. Since it is common for the content of a lecture to be changed while it is being given, the summaries will appear after, not before, the class.

Often, the summaries will include links to Flash animations. These require that you have the Flash player installed on your computer. The player is available free from


For most students, the materials given in these summaries are best used as a supplement to the lectures themselves. Do not use them as a substitute for attending class.


Class and Date Brief Summary of the Lecture  
1 - Mon. Sept. 8, 2003 Introduction to the structure of the course. About lectures and tutorials. About the laboratories. Introduction to Physics and learning Physics.
2 - Wed. Sept. 10, 2003 Changing lab/tutorial sections. PHY138 Representative Assemblies. Problem solving. Textbook Reference. Begin Chapter 1: units, orders-of-magnitude, coordinate systems, vectors.
3 - Mon. Sept 15, 2003 Tutorials begin this week. Problem Set #2. Finish Chapter 1: vector subtraction, addition by coordinates, unit vectors. Began and nearly finished Chapter 2: speed and velocity, instantaneous velocity, constant velocity, constant speed, acceleration, constant acceleration.
4 - Wed. Sept. 17, 2003 Mathematical synonyms. Tutorials and Representative Assemblies. Finish Chapter 2: freely falling objects. Began Chapter 3: a detailed analysis of projectile motion.
5 - Mon. Sept. 22, 2003 Fermi Problems. Problem Set #3. Finished Chapter 3: finished projectile motion, centripetal acceleration, radial acceleration, Galilean relativity. Began Chapter 4: Newton's first law of motion, inertia, inertial reference frames.
6 - Wed. Sept. 24, 2003 Representative Assembly for Thursday's tutorials. Yom Kippur. Went back and finished Chapter 3. Finished Chapter 4 except for some examples: inertial and gravitational mass, Newton's third law of motion, the ballistocardiogram.
7 - Mon. Sept. 29, 2003 Problem Set #4. How many problems should you solve? Getting into and out of Con Hall. Finished Chapter 4: Example 4.5 plus extensions. Did the parts of Chapter 5 we said we would discuss: centripetal force, fundamental forces of nature, the gravitational field. Began Chapter 6: systems and environment, defining the work.
8 - Wed. Oct. 1, 2003 Representative Assembly for Friday's tutorials. Drop-In Centre beginning. Reminder about my office hours. Chapter 6 continued: dot product, work by a non-constant force, Hooke's law and the work done by a spring, work - kinetic energy theorem, began a discussion of non-isolated systems and conservation of energy.
9 - Mon. Oct 6, 2003 Problem Set #5. Finished Chapter 6: conservation of energy, power. Discussed the metabolic rate of organisms, and how it is related to the mass of the animal. Began Chapter 7: introduced the gravitational potential energy.
10 - Wed. Oct 8, 2003 Test conflicts. Labs starting next week. About the quiz. Continuing Chapter 7: defining the potential energy, conservation of mechanical energy, conservative forces, the relation between the potential energy and the force.
11 - Wed. Oct 15, 2003 Problem Set #6. Future classes. Wednesday Representative Assembly. Finished Chapter 7: gravitational and electric potential energy, energy diagrams. Began Chapter 8: defined momentum, a new "improved" Newton's 2nd Law of Motion, conservation of momentum.
12 - Mon. Oct 20, 2003 Democracy, simulations and reality. Quiz results. Finish Chapter 8: impulse, elastic and inelastic collisions. Began Chapter 10: radian measure, angular velocity, angular acceleration, the direction of the vectors of circular motion.
13 - Wed. Oct 22, 2003 Thursday Representative Assembly. Finished Chapter 10: moment of inertia, kinetic energy, torque, vector products, equilibrium, angular momentum. The next class.
14 - Mon. Oct 27, 2003 Studying for tests. A review for the test.
Wed. Oct 29, 2003
Friday Representative Assembly. About the test. A discussion of error analysis, a laboratory topic.
Results of the Mechanics test.