PHY 3221 "Mechanics I"
Class Diary for Fall 2017

 

Date Notes
Monday 8/21 Introductions, course policies. Syllabus. UF grading policy for assigning grade points.
Reading material: sections 1.1-1.3.
Wednesday 8/23 (no quiz today) Reading material: section 1.4.
Cartesian coordinates. Vectors and vector operations: addition, subtraction, dot and cross products. Differentiation of vectors. Position, velocity, acceleration.
Exercises: Problems 1.1, 1.4 (answer: 55.15 deg), 1.9, 1.19.
Friday 8/25 Reading material: section 1.5.
Equation of the orbit (trajectory). Reference frames. Newton's laws. Newton's second law in Cartesian coordinates. Motion under the influence of a constant force. Example 1.1: Block sliding down an incline.
Exercises: Problems 1.11, 1.24, 1.25, 1.26.
Monday 8/28 Reading material: section 1.6.
Finish the block sliding down an incline. Third law and conservation of momentum.
Exercises: Problem 1.28, 1.35, 1.36, 1.37, 1.38, 1.39.
Wednesday 8/30 (quiz day!) HW 1 is due (Exception: Problems 1.46 and 1.49 will be accepted until Friday Sep. 1)
Reading material: sections 1.7 and 2.1.
Two-dimensional polar coordinates. Newton's second law in polar coordinates. Example 1.2.
Exercises: Problems 1.42 and 1.43.
Friday 9/1 Reading material: section 2.2.
Examples of motion under different types of forces: a) constant; b) time-dependent; c) velocity-dependent.
Exercises: Problems 1.41, 1.45; 2.7, 2.8.
END OF CHAPTER 1. Additional recommended problems for self-study in preparation for the first exam:
1.3; 1.6; 1.7; 1.12; 1.13; 1.15; 1.18; 1.20; 1.47; 1.48.
Monday 9/4 Labor Day - no class.
Wednesday 9/6 Reading material: section 2.2. Velocity-dependent forces. Terminal velocity. Horizontal motion with linear drag. Vertical motion with linear drag.
Friday 9/8 UF closed due to Hurricane Irma.
Monday 9/11 UF closed due to Hurricane Irma.
Wednesday 9/13 UF closed due to Hurricane Irma.
Friday 9/15 Reading material: sections 2.3 and 2.4. Section 2.3: Equation for the trajectory in a linear medium, equation for the horizontal range, solving for the range using perturbation theory in 1/tau. Section 2.3: Quadratic air resistance: the general case (coupled equations); solutions for purely horizontal motion and for purely vertical motion. Problem 2.12: force which depends only on the position. Problem 2.13: the harmonic oscillator.
Monday 9/18 HW 2 is due Reading material: section 2.5 and the end of section 2.7 (page 71). We will be skipping section 2.6 and instead solving the equations by using the method outlined in problem 2.54. Motion of a point charge in a constant magnetic field in the z direction. Equations of motion. Solving for the motion along the z direction. Equations of motion in the transverse plane. Decoupling the x and y equations. General solution of a second order linear differential equation with constant coefficients. Solution for the velocity and for the position. Trajectory. Cyclotron frequency. Additional recommended problems: 2.55.
END OF CHAPTER 2. Additional recommended problems for self-study in preparation for the first exam:
2.5; 2.6; 2.9; 2.15; 2.23; 2.24; 2.26; 2.27; 2.29; 2.30; 2.31; 2.32; 2.36; 2.37; 2.38; 2.39; 2.40.
Wednesday 9/20 (quiz day!) HW 3 is due Reading material: sections 3.1-3.2. Momentum conservation (section 1.5 and problem 1.28). Example 3.1: inelastic collision of two bodies. Section 3.2: Rocket motion. Thrust.
Friday 9/22 Reading material: Section 3.3. Computing the center of mass of point mass configurations and extended bodies. Examples: Problems 3.15, 3.16 and 3.17. The CM of a solid cone (example 3.2).
Review session for the first exam. Review of the scalar and the vector product. Vector products of the Cartesian unit vectors. Problem 2.55 (the basic principle of a velocity selector).
Additional problems for self-study from Chapter 3: 3.1, 3.2, 3.5, 3.7, 3.9, 3.10, 3.12, 3.22.
Monday 9/25 First Exam: Chapters 1-3. The exam will cover Chapter 1, Chapter 2 and the first three sections (3.1-3.3) from Chapter 3.
HW 4 is due today before the exam
Wednesday 9/27 (no quiz today) Reading material: sections 3.4-3.5. Review: cross product of two vectors. Area of a triangle, Problem 3.24 (see also problem 1.18). Kinematical variables for rotational motion. Angular velocity, angular acceleration, angular momentum, torque, moment of inertia. Conservation of angular momentum. Kepler's second law. Section 3.5: Angular momentum for systems of particles.
Friday 9/29 Example 3.3. Lump of Putty colliding with a turntable. Parallel axis theorem. Example 3.4. A sliding and spinning dumbbell. Problem 3.35. A disk rolling down an inclined plane. Problem 3.32. Moment of inertia of a uniform sphere.
END OF CHAPTER 3. Additional recommended problems for self-study in preparation for the second exam: 3.24, 3.25, 3.26, 3.31, 3.33.
Monday 10/2 Begin Chapter 4. Reading material: sections 4.1-4.4. Kinetic energy and work. Work-KE theorem. Example 4.1. Three line integrals. Conservative forces: definition. Conservative forces and potential energy. Conservation of mechanical energy. Section 4.3. Force as the gradient of potential energy. Section 4.4. The curl condition for conservative forces.
Wednesday 10/4 (quiz day!) Main discussion topic: Conservative forces and potential energy. Constant forces. Central forces (Coulomb force: Example 4.5 and problem 4.22; Gravity force: Problem 4.21). Finding the potential energy from a given force field. Checking if the force is conservative, computing the potential energy. Cartesian versus spherical coordinates, Problem 4.43. Reading material: section 4.5.
Friday 10/6 Homecoming - no class.
Monday 10/9 HW 5 is due Reading material: sections 4.6-4.8. Review the problems from quiz 3. Calculating the force from a potential energy (Problems 4.12, 4.13). Direction of the gradient, direction of the force. Sections 4.6 and 4.7: One-dimensional systems. Graphs of the potential energy. Equilibrium points. Stable and unstable equilibrium. Turning points.
Wednesday 10/11 Problem solving session. Problems: 4.26, 4.31, 4.35. Example 4.3 (block sliding down a plane). Example 4.6 (dropping a stone from a tower). Example 4.7 (cube balanced on a cylinder).
Friday 10/13 Reading material: sections 4.9-4.10. Review of central forces (section 4.8). Problems 4.43, 4.44. Energy of interaction between two particles. Total energy of a two-particle system. Elastic collisions. Example 4.8 (see also problem 3.5). Problems 4.46, 4.47. The energy of a multiparticle system. Rigid bodies. Example 4.9: A cylinder rolling down an incline.
Begin Chapter 5. Section 5.1. Hooke's law. Expansion of the potential energy around a stable equilibrium position.
Monday 10/16 HW 6 is due Reading material: section 5.2. Mathematics of oscillations. Solving linear second order differential equations with constant coefficients. General solution to the homogeneous equation. Characteristic equation. Particular solutions to the inhomogeneous equation. Simple harmonic oscillator. Two forms of the solution. Total energy of the oscillator.
Wednesday 10/18 (quiz day!) Reading material: sections 5.3-5.4. The third form of the harmonic oscillator solution. Example 5.2. A bottle in a bucket. Example 1.2. An oscillating scateboard. Section 5.3. Two-dimensional oscillators.
Friday 10/20 Reading material: sections 5.4-5.6. Section 5.4. Damped oscillators. Undamped, underdamped, overdamped and critically damped oscillator. Dependence of the decay parameter on beta (see also Problem 5.20). Section 5.5. Driven damped oscillations. General solution to the homogeneous equation and a particular solution to the inhomogeneous equation (see also Problem 5.34).
Monday 10/23 No class. KM out of town.
Wednesday 10/25 (no quiz today) HW 7 is due Section 5.6. Resonance. Resonant frequency (see also problem 5.40). Width of the resonance, Q-factor. The phase at the resonance.
Review session for the second exam.
Additional problems from Chapter 5: 5.1, 5.2, 5.3, 5.6, 5.8, 5.9, 5.10, 5.16, 5.21, 5.22, 5.23, 5.25, 5.26, 5.28, 5.42, 5.43.
Friday 10/27 Second Exam. Chapters 4 and 5. The exam covers up to and including section 5.6.
Monday 10/30 Solving problems with dimensional analysis. You can refer to these notes, in particular see examples 3.1, 3.2 and 3.3.
Wednesday 11/1 (no quiz today) Go over some of the problems from the second exam. Reading material: section 6.1. Formulation of mechanics problems as boundary value problems. Comparing different possible trajectories and choosing the optimal one. "Cost" function for a given trajectory. Analogy with vehicle routing.
Friday 11/3 Reading material: section 6.2. Snell's law (Problem 6.4). Derivation of the Euler-Lagrange equation.
Monday 11/6 Reading material: sections 6.3-6.4 and section 7.1. Applications of the Euler-Lagrange equations. A particle moving in one dimension under a conservative force (compare to example 7.1). A first integral when the function does not depend on y (the dependent variable), Problem 6.10 and momentum conservation in mechanics. A first integral when the function does not depend on x (the independent variable), Problem 6.20 and energy conservation in mechanics. Shortest path between two points in 2 dimensions (Example 6.1) and in 3 dimensions (Problem 6.27). The brachistochrone (Example 6.2). Isochronous curves. The brachistochrone as a cycloid (Problem 6.14).
Wednesday 11/8 !!!EXTRA CREDIT EXAM!!!
HW 8 is due
Friday 11/10 Veteran's day - no class.
Monday 11/13 Reading material: section 7.1-7.6. Sec. 7.1: Lagrange's equations for unconstrained motion. Different formulations of classical mechanics: Newtonian, Hamilton's principle, Lagrange's equations. Sec. 7.3: Constrained systems in general. Generalized coordinates. Generalized forces and generalized momenta (see Sec. 7.6). Counting the relevant number of degrees of freedom. The four steps to be followed in solving any problem by the Lagrangian method (page 258). Example 7.2. One particle in two dimensions using polar coordinates.
Wednesday 11/15 (quiz day!) Reading material: sections 7.1-7.5. Examples: Sec. 7.2: Plane pendulum. Example 7.5: A block sliding on a sliding wedge.
Friday 11/17 HW 9 is tentatively due Reading material: sections 7.5-7.7. The example of Fig. 7.4: pendulum in an accelerating railroad car. Unnatural (rheonomous, forced) coordinates. Natural (scleronomous) coordinates. Cyclic (ignorable) coordinates. Example 7.3: Atwood's machine. Example 7.6: Bead on a spinning wire hoop (see also Example 7.7 and problem 7.26).
Monday 11/20 HW 9 is officially due More examples practicing the Lagrangian method. Problem 7.30: pendulum inside a railroad car. Problem 7.34: car connected to a massive spring. Problem 7.36: plane pendulum on a spring. Example 7.4: particle on a cylinder.
Wednesday 11/22 Pre-Thanksgiving holiday - no class.
Friday 11/24 Thanksgiving holiday - no class.
Monday 11/27 Reading material: sections 7.8 and 7.10 (skip 7.9). 7.8: More about conservation laws. Noether's theorem and cyclic coordinates. Conservation of total momentum. Conservation of energy. Hamiltonian. 7.10: Lagrange multipliers and constraint forces. Example 7.8: Atwood's machine using a Langange multiplier.
Wednesday 11/29 (no quiz today) HW 10 is due Review session for the third exam: Example 7.4, Problems 7.16, 7.18, 7.37, 7.48, 7.51, 7.52.
Suggested additional problems:
Chapter 6: Problems 6.6, 6.7, 6.8, 6.9, 6.11, 6.17.
Chapter 7: Problems 7.1, 7.3, 7.9, 7.11, 7.15, 7.17, 7.21, 7.28.
Friday 12/1 Third Exam. Chapters 6 and 7.
Monday 12/4 Computer demos. The mathematica notebook file is posted on canvas.
Solving differential equations with mathematica. Example 1.2: An oscillating scateboard. Comparing the full solution to the linearized version (the harmonic oscillator).
Section 5.3: Two-dimensional harmonic oscillators. Lissajous curves. Plotting with Mathematica.
Overview of the material to be covered in the Spring semester.
Wednesday 12/6 (no quiz today) Computer demos. A second mathematica notebook is available on canvas.
Section 5.7: Fourier series. Computing the Fourier coefficients. Mathematica exercise: Approximating a periodic function with a truncated Fourier series. Example 5.4: Rectangular pulse.