Welcome to PHYSICS 220 (Section 2) Prof. Yulia Pushkar Kinematics Forces Energy and Momentum Rotations Fluids Oscillations/Waves/Sound Thermodynamics Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Textbook The textbook is College Physics, Vol I, by Nicholas J. Giordano (Brooks/Cole). We will cover almost all of the topics in this volume, at a rate of one chapter per week! Very Fast! Come prepared! Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Course Web Site http://www.physics.purdue.edu/phys220 Course Syllabus Policies Grading scheme Exams & iClicker exercises Lab Syllabus Tentative Class Calendar Pre-lecture reading assignments Homework due dates CHIP User’s Guide Homework Grades Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Class Format Lecture Section 2: Time: Monday, Wednesday 11:30 - 12:20 Lecture Room: PHYS 114 Instructors: Prof. Yulia Pushkar Office Hours: 12:30 am – 1:30 pm on Monday and Wednesday Office: PHYS 70 Phone: 49-63279 Email: ypushkar@purdue.edu (please include on the subject line: PHYS 220) Recitation Section 2: Time: Friday 11:30 - 12:20 Instructor: Deepak Pandey Office Hours: Friday: 12:30 AM - 5:30 PM Office: PHYS 11A Phone: 49-43018 Email: dpandey@purdue.edu CHIP coordinator: Dr. V.K. Saxena, PHYS 176 Laboratory: Coordinator: Dr. A. Lewicki, Office: PHYS 142 Lab Room: PHYS 121 Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Homework We will use CHIP (Computerized Homework In Physics) for homework assignments The homework is due by 10 am on Fridays Homework is computer graded 100% if completed before the deadline 75% if completed within three days of the deadline 50% if completed after three days but within one week of the deadline 0% after one week past the deadline There is a limit on the number of attempts allowed. Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 iClicker We will use iClicker for interactive lecture and recitation exercises One point for participating in each exercise Two points for each correct answer iClicker can be purchased at the Purdue bookstore Registration: You must register your iClicker on CHIP! Use serial number at the back of your iClicker Go to CHIP -> Student Gradebook DO NOT register on the iClicker web site! Deadline: by the end of this week We will start to use iClicker next week! Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Exams and Grades Exams: There will be two midterm exams and one final exam. All exams are closed-book. The final exam will be cumulative. Exam 1: Feb 22, 2010, 6:30 – 7:30 PM Exam 2: Mar 29, 2009, 6:30 – 7:30 PM Final: TBA (2 hours) Grades: The final grade will be determined on the following basis: 300 points final exam 300 points two evening exams (150 points each) 150 points laboratory 100 points CHIP homework 50 points recitation exercises 100 points lecture exercises No excused iClicker exercises. You must pass the lab in order to pass the course. Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Tips Pre-lecture reading Come to the lectures prepared! Things to pay attention to Concepts, connections, motivation: Lecture Problem solving: Recitation + Homework Hands-on lab Taking notes Lecture notes can be downloaded from the course web site But they are sketchy … you need to fill in details in class Post-lecture reading See if there are still things you do not understand Seeking help See us during office hours! Physics Help Center Lecture 1 Purdue University, Physics 220

Why it is cool to study Physics? The science of matter and energy, and the interactions between them Matter and energy are fundamental to all areas of science The study of the natural or material world and phenomena Meaning of physics from the Greek for Nature Natural philosophy Oldest science All scientists were originally physicists

Purdue University, Physics 220 About Me Biophysics: From Photosynthesis to future energy solutions Imaging metals in the brain with X-ray techniques Want to learn more? Visit http://www.physics.purdue.edu/people/faculty/pushkar.shtml Lecture 1 Purdue University, Physics 220

Types of Problems We will encounter various types of problems Quantitative problems Give numerical information and use calculations Concept checks Test your general understanding of a law and its application Reasoning and relationship problems Indentify what important information might be “missing”

Problem Solving Strategies Recognize the key physics principles Need a conceptual understanding of the laws, how they are applied, and how they are interrelated Sketch the problem Show the given information / include a coordinate system Identify the important relationships Use the given information and the unknown quantities to determine what laws apply Solve for the unknown quantities What does it mean? Does the answer make sense? Think about your answer

Dealing With Numbers Scientific notation Significant figures

Scientific notation Number of people leaving on the Earth (2007): Prefix (abbreviation) Power of Ten Peta (P) 1015 Tera (T) 1012 Giga (G) 109 Mega (M) 106 Kilo (k) 103 Hecto (h) 102 Deci (d) 10-1 Centi (c) 10-2 Milli (m) 10-3 Micro () 10-6 Nano (n) 10-9 Pico (p) 10-12 Femto (f) 10-15 Number of people leaving on the Earth (2007): 6,600,000,000 or 6.6 x 109

Significant figures – show accuracy Your height is: (A) 5.9 ft (B) 5.90 ft B is more accurate than A, as its result contains more significant figures. Implies that true value lies between 5.89 ft and 5.91 ft A digit is significant if it is meaningful with regard to the accuracy of the value

Significant Figures in Calculations Multiplying and dividing Use the full accuracy of all known quantities when doing the computation After completing the calculation, round the answer to the number of significant figures present in the least accurate starting quantity Example: 976 x 0.000064 m = 0.062464 m~ 0.062 m Due to the 2 significant figures in the 0.000064

Significant Figures - cont’d What is the perimeter of a circle of radius 1.2 m? L = 2r x 3.1415926 … x 1.2 = 7.539822 … m L = 7.5 m What about: 3.1415 + 0.1 = 3.2415 or 0.1415 - 0.02 = 0.1215? Ans: 3.2 or 0.12 Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Units To communicate the result of a measurement for a quantity, a unit must be defined! Defining units allows everyone to relate to the same fundamental amount. Always write down units and carry the units through all of the calculations. We use the SI system Length: meter (m) Mass: kilogram (kg) Time: second (s) Dimensional Analysis: Both sides of an equation must have the same units. Can be used to verify equations, answers. Example: density [kg/m3]  = m [kg] / V [m3] 1 meter = 3.281 ft 1 kg = 2.205 pounds Lecture 1 Purdue University, Physics 220

Trigonometry Generally will use only right triangles Pythagorean Theorem r2 = x2 + y2 Trig functions (r=hypotenuse) sin θ = y / r cos θ = x / r tan θ = y / x Trigonometric identities sin² θ + cos² θ = 1 Other identities are given in appendix B and the back cover To find an angle, you need to use the inverse of a trig function If sin θ = y/r then θ = sin-1 (y/r)= ascsin(y/r) Angles in the triangle add up to 90° α + β = 90° Complementary angles sin α = cos β

Vectors vs. Scalars A scalar is a quantity that requires only a magnitude (with unit) – time [s], mass [kg]. A vector is a quantity that requires a magnitude and a direction (is represented by arrows) –displacement [m], force [N], velocity [m/s], acceleration [m/s2].

Vector Representation The length of the arrow indicates the magnitude of the vector The direction of the arrow indicates the direction of the vector with respect to a given coordinate system Vectors are written with an arrow over a boldface letter Mathematical operations can be performed with vectors: add, subtract, multiply by constant.

Adding Vectors Draw the first vector Draw the second vector starting at the tip of the first vector Continue to draw vectors “tip-to-tail” The sum is drawn from the tail of the first vector to the tip of the last vector

Adding Vectors Using Components Assume you are adding two vectors: To add the vectors, add their components Cx = Ax + Bx Cy = Ay + By Then the magnitude and direction of C can be determined Ax = A cos θ; Ay = A sin θ

Purdue University, Physics 220 Motion -x +x The variables are time and position t = ti start of observations at a point xi t = tf end of the observations at a point xf The object is in motion and velocity is (change in position)/time Velocity can change => acceleration (change in velocity)/time All quantities except time are vectors; the vector “nature” is contained in whether the quantity is positive or negative Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Displacement = change in position during a particular time interval This type of x(t) plot shows the position of an object at any time, e.g., x (m) 3 Position at t=3 s, x(3) = 1 m t (s) 4 Displacement between t=1 s and t=5 s Dx = 1.0 m - 2.0 m = -1.0 m -3 Lecture 1 Purdue University, Physics 220

Purdue University, Physics 220 Question Given the train’s initial position and its final position what is the displacement of the train? Answer: B A) -26 km B) -29 km C) +29 km D) -23 km E) +23 km Lecture 1 Purdue University, Physics 220

Displacement vs Distance Displacement is a vector Only depends on the initial and final positions Independent of actual paths between the initial and final positions Distance is a scalar Depends on the initial and final positions as well as the actual path between them Lecture 1 Purdue University, Physics 220