Lecture 1Purdue University, Physics 2201 –Kinematics –Forces –Energy and Momentum –Rotations –Fluids –Oscillations/Waves/Sound –Thermodynamics Welcome to PHYSICS 220 Prof. Yulia Pushkar

Lecture 1Purdue University, Physics 2202 Textbook The textbook is College Physics, Vol I, by Nicholas J. Giordano (Brooks/Cole, second edition). We will cover almost all of the topics in this volume, at a rate of one chapter per week! Very Fast! Come prepared!

Lecture 1Purdue University, Physics 2203 Course Web Site 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 1Purdue University, Physics 2204 Class Format Lecture Section 2: –Time: Monday, Wednesday 11: :20 –Lecture Room: PHYS 114 –Instructors: Prof. Yulia Pushkar –Office Hours: 4 -5 pm on Monday and Wednesday –Office: PHYS 70 Phone: (please include on the subject line: PHYS 220) Recitation Section 2: –Time: Friday 11: :20 –Instructor: Adrien Chauvet Office: PHYS 182 Phone: –CHIP coordinator: Dr. V.K. Saxena, PHYS 176 Laboratory: –Coordinator: Dr. A. Lewicki, Office: PHYS 142 –Lab Room: PHYS 121

Lecture 1Purdue University, Physics 2205 Homework We will use CHIP (Computerized Homework In Physics) for homework assignments The homework is due by …..(we will take a poll next lecture by i-clicker) 10 am Friday 10 am Saturday 10 am Sunday 11 pm Sunday ? 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

Lecture 1Purdue University, Physics 2206 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! cker_register.pdf –Deadline: by the end of this week We will start to use iClicker next week!

Lecture 1Purdue University, Physics 2207 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 21, 2012, 6:30 – 7:30 PM –Exam 2: Mar 26, 2011, 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 1Purdue University, Physics 2208 Tips Pre-lecture reading / reviewing the home work assignment / lecture slides –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

Today’s Lecture What is physics? Problem Solving Scientific notations and significant figures Units of measure Math of Physics –Algebra, Geometry –Vectors Motion Lecture 1Purdue University, Physics 2209

Why is it 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

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? –Dimentional analysis

Dealing With Numbers –Scientific notation –Significant figures

Scientific notation Number of people leaving on the Earth (2007): 6,600,000,000 or 6.6 x 10 9

Scientific notation Prefix (abbreviation) Power of Ten Peta (P)10 15 Tera (T)10 12 Giga (G)10 9 Mega (M)10 6 Kilo (k)10 3 Hecto (h)10 2 Deci (d)10 -1 Centi (c)10 -2 Milli (m)10 -3 Micro (  ) Nano (n)10 -9 Pico (p) Femto (f)10 -15

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 m = m~ m Due to the 2 significant figures in the

Lecture 1Purdue University, Physics Significant Figures What is the perimeter of a circle of radius 1.2 m? What about: = or = ? Ans: 3.2 or 0.12 L =  r  x … x 1.2 = … m L = 7.5 m With scientific notations: 3.2* *10 -3 ? Ans: 6.67*10 -3

Lecture 1Purdue University, Physics 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/m 3 ]  = m [kg] / V [m 3 ] 1 meter = ft 1 kg = pounds

Trigonometry Generally will use only right triangles Pythagorean Theorem r 2 = x 2 + y 2 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) A vector is a quantity that requires a magnitude and a direction (is represented by arrows)

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, dot product, cross product.

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

Vectors Decomposition A x = A cos θ; A y = A sin θ

Adding Vectors Using Components Assume you are adding two vectors: To add the vectors, add their components C x = A x + B x C y = A y + B y Then the magnitude and direction of C can be determined