PHY 2048C General Physics I with lab Spring 2011 CRNs 11154, & Dr. Derrick Boucher Assoc. Prof. of Physics

Syllabus Course Resources tour LON-CAPA tour Standard Lecture Format PRS clickers Chapter 1 Chapter 2 Outline for Lecture 1

Course Resources Dr. Boucher’s website Syllabus us%20s11%20boucher.pdf Schedules Pschedule.pdf

Course Resources, cont. Lab Resources Schedule: pring_2011.htm Procedures, other helpful files: s.htm

Course Resources, cont. Equation sheet (still being prepared) All the equations you’ll need for the course Conversion factors and constants Provided for every exam Useful for study So, what do you need to know? Mensuration formulas (areas, volumes, etc.) Geometry, trig and calculus Metric prefixes giga, mega, kilo, centi, milli, micro, nano

LON-CAPA Our online homework system Free to use Locally administered (problems get solved!) Allows discussion among students, instructor Take a look:

Standard Lecture Format 1.Announcements, glimpse at schedules 2.Handouts 3.PRS clicker logins (attendance) 4.Old business (handing graded items back, reviewing homework, etc.) 5.(Maybe) quiz on past material and/or current reading 6.New concepts and equations (kicking the tires) 7.Example Problem(s) 8.Repeat 6 & 7 as necessary…

Chapter 1 and 2 Practice Problems Chap 1: 1, 3, 7, 13, 15, 19, 23, 25, 27, 29, 37, 41 Chap 2: 3, 7, 9, 11, 31, 57, 63, 69, 71 Unless otherwise indicated, all practice material is from the “Exercises and Problems” section at the end of the chapter. (Not “Questions.”)

Chapter 1 READ IT Review and learn as necessary Some highlights follow

The Particle Model For simple motion we can consider the object as if it were just a single point, without size or shape. All the mass is concentrated at that point. A particle has no size, no shape, and no distinction between top and bottom or between front and back.

Making a Motion Diagram Simplify a “movie” in one diagram Position at equal time intervals Equally spaced points represents constant speed; the car travels equal distances in equal times tree

EXAMPLE 1.1 Headfirst into the snow

Average Speed, Average Velocity To quantify an object’s fastness or slowness, we define a ratio as follows: Average speed does not include information about direction of motion. Average velocity does include direction. The average velocity of an object during a time interval Δt, in which the object undergoes a displacement Δr, is the vector In one dimension, direction is either + or – (it’s up to you which real direction + or – actually means). Then, r is x or y.

Instantaneous Velocity Average velocity is calculated over an extended period of time. As ∆t gets smaller and smaller, we can think of the velocity at a particular instant in time. This is especially useful when velocity changes. Graphically, v is the slope of a line tangent to the position vs. time curve. You may (should) recognize this as the derivative! Notation in text: “s” means x, y or z…whatever direction you are dealing with

Example problem Chapter 2 #6 (p. 65)

PRS Clicker Questions

Sample question; Dr. Boucher’s favorite color is, A. Blue B. Green C. Chartreuse D. Red E. None. Dr. Boucher sees in black-and-white.

At the turning point of an object, A. the instantaneous velocity is zero. B. the acceleration is zero. C. both A and B are true. D. neither A nor B is true. E. This topic was not covered in this chapter.

REDO (after discussion) At the turning point of an object, A. the instantaneous velocity is zero. B. the acceleration is zero. C. both A and B are true. D. neither A nor B is true. E. This topic was not covered in this chapter.

Which position-versus-time graph represents the motion shown in the motion diagram?

Which velocity-versus-time graph goes with the position-versus-time graph on the left?

REDO Which velocity-versus-time graph goes with the position-versus-time graph on the left?

Average acceleration To quantify an object’s change in motion, we define acceleration: Average acceleration should include direction. The average velocity of an object during a time interval Δt is a vector. In one dimension (chapter 2), direction is either + or – (it’s up to you which real direction + or – actually means). Then, “s” is x or y.

Example problem Chapter 2 #8 (p. 65)

1604 Galileo experiments with falling bodies, especially ones “falling” down an inclined plane Finally formulates the equations you see above. “s” means x, y or z…whatever direction you are dealing with

Using the kinematic (Galileo’s) equations: They only apply AFTER motion has begun Do not worry about the details of HOW something got into motion As soon as conditions change (a new force appears, an old force disappears, a collision…) you need to apply a new set of equations “kinematics”

Example problem Chapter 2 #14 (p. 66)

Example problem Chapter 2 #66 (p. 70)

Free fall technically means that gravity is the only force acting on the object The gravitational force is constant Therefore, so is the acceleration, so Galileo’s equations apply! a = “g” = 9.8 m/s 2 near the Earth’s surface Free Fall IMPORTANT: g = 9.8 but a can be OR −9.8 depending on which way you define down to be. It is customary, and smart, to use − for down!

A 1-pound block and a 100-pound block are placed side by side at the top of a frictionless hill. Each is given a very light tap to begin their race to the bottom of the hill. In the absence of air resistance A. the 1-pound block wins the race. B. the 100-pound block wins the race. C. the two blocks end in a tie. D. there’s not enough information to determine which block wins the race.

Example problem Chapter 2 #16 (p. 66)

Motion on an Inclined Plane

Example problem Chapter 2 inclined plane (not in text)

Read the material in chapter 2 and review your calculus as necessary. For now, I will focus on using derivatives more than integrals. Calculus and Motion

Example problem Chapter 2 derivatives and motion (not in text)