Welcome to Physics 215 General Physics I Honors

Welcome to Physics 215! (General Physics I – Honors & Majors) *Please pick up a syllabus* Physics 215 – Fall 2014 Lecture 01 -1 1

SU PHY 215 General Physics I Fall 2014 Course staff: • Lecturer: Prof. Britton Plourde (bplourde@syr. edu) • Workshop instructor: -- Prashant Mishra (prmishra@syr. edu) Physics 215 – Fall 2014 Lecture 01 -1 2

Physics Laboratory Course (PHY 221) • Instructor: Sampere • Lab section taught by teaching assistant • Separate course – Register separately – Independently graded • Lab manuals will be distributed during lab meetings Physics 215 – Fall 2014 Lecture 01 -1 3

Course Information (http: //physics. syr. edu/courses/PHY 215. 14 Fall/index. html) • Books - Physics for Scientists and Engineers, Vol. 1, 3 rd edition, R. D. Knight - Accompanying Student Workbook • Announcements/reminders of exams and homework assignments • Course outline, objectives • Course calendar • Lecture slide shells • Homework/exam solutions, practice exams on Blackboard Physics 215 – Fall 2014 Lecture 01 -1 4

Lectures • Finish reading assignment beforehand! • During lecture, we will. . . – Discuss key concepts – Observe demonstrations – Work through sample problems – Consider conceptual questions • Shells of lecture slides available evening before Physics 215 – Fall 2014 Lecture 01 -1 5

Workshops • Graduate teaching assistant • During workshops you will work in groups • Workbook problems, end-of-chapter problems, other worksheets, practice exams • TA is there to help you but not to lecture • Hands-on learning experience! • Attendance is required Physics 215 – Fall 2014 Lecture 01 -1 6

Physics 215 Fall 2014 Agenda for this week: Tuesday: Intro, position, velocity Wednesday: Motion diagrams (Workbook) Thursday: Kinematics and graphs Friday: Problem Solving Activity on Motion with graphs Physics 215 – Fall 2014 Lecture 01 -1 7

Exams • 3 Exams during semester – Each exam will focus on material from previous ~45 weeks, but may include earlier material as well – 80 -minutes each, during lecture period – Closed book, but can bring one 8. 5” x 11” sheet of handwritten notes (no photocopies) – Practice exam questions in workshop before each exam – Solutions posted online after each exam is graded – Exam 1 -- Sept. 18 • Final exam – Cumulative – 2 hours -- Dec. 11, 12: 45 -2: 45 PM Physics 215 – Fall 2014 Lecture 01 -1 8

Homework • Weekly homework – Typically due in Wednesday workshop, except as noted – Assigned at least one week before due date – Combination of end-of-chapter problems, conceptual questions, exam-style problems (print out from course website) • Reminders of assignments on course website • Solutions to select problems posted online after due date • No late homework will be accepted • HW 1: – Ch. 1 (Knight): 42, 56; Ch. 2 (Knight): 26, 30, 40 – due Wednesday Sept 3 rd in recitation – TA will grade each HW set with a score from 0 to 10 Physics 215 – Fall 2014 Lecture 01 -1 9

Grades • • Exams 1 -3 (drop lowest) Final exam Homework (drop lowest 2) Workshop participation 40% 25% 20% 15% – (can miss 3 meetings w/o penalty) The grades are normalized such that the average course grade is a B- or better, depending on the performance of the class as a whole. Physics 215 – Fall 2014 Lecture 01 -1 10

Objectives for this course: – Develop good understanding of a few important concepts – Reason qualitatively and quantitatively – Learn to apply to unfamiliar situations – Get a flavor of more advanced topics outside of the standard Mechanics curriculum Physics 215 – Fall 2014 Lecture 01 -1 11

Course Outline • Weeks 1 -4: Motion (Kinematics) • Weeks 5 -6: Newton’s Laws (Dynamics) • Weeks 7 -9: Energy, momentum • Weeks 10 -11: Extended objects, rotations • Weeks 12 -13: Gravity, oscillations • Week 14: Thanksgiving break • Week 15: Fluids Physics 215 – Fall 2014 Lecture 01 -1 12

Kinematics-describing motion 1 D Physics 215 – Fall 2014 Lecture 01 -1 13

Position and Displacement • Neglect shape of object and represent by point moving in space (1 D) • Position may be specified by giving distance to origin – x coordinate • Choice of origin arbitrary! – many choices to describe same physical situation. • Hence x-coordinate not unique Physics 215 – Fall 2014 Lecture 01 -1 14

Displacement = change in position x 2 Q x 1 O P origin • Displacement (P Q) = x 2 - x 1 = Dx • Displacement does NOT depend on origin! Physics 215 – Fall 2014 Lecture 01 -1 15

Displacement • Displacement is ‘distance plus direction’ • Displacement Dx is a vector quantity – change in position (vector) of object • In one dimension, this amounts to a sign – Displacement towards increasing x – positive – Displacement towards decreasing x – negative Physics 215 – Fall 2014 Lecture 01 -1 16

Velocity • Definition: Average velocity in some time interval Dt is given by vav = (x 2 - x 1)/(t 2 - t 1) = Dx/Dt • Displacement Dx can be positive or negative – so can velocity – it is a vector, too • Average speed is not a vector, just (distance traveled)/Dt Physics 215 – Fall 2014 Lecture 01 -1 17

Discussion • Average velocity is that quantity which when multiplied by a time interval yields the net displacement • For example, driving from Syracuse Ithaca Physics 215 – Fall 2014 Lecture 01 -1 18

Instantaneous velocity • But there is another type of velocity which is useful – instantaneous velocity • Measures how fast my position (displacement) is changing at some instant of time • Example -- nothing more than the reading on my car’s speedometer and my direction Physics 215 – Fall 2014 Lecture 01 -1 19

Describing motion • Average velocity (for a time interval): vaverage = • Instantaneous velocity (at an instant in time) vinstant = v = • Instantaneous speed |v| Physics 215 – Fall 2014 Lecture 01 -1 20

Instantaneous velocity • Velocity at a single instant of time • Tells how fast the position (vector) is changing at some instant in time • Note while Dx and Dt approach zero, their ratio is finite! • Subject of calculus was invented precisely to describe this limit – derivative of x with respect to t Physics 215 – Fall 2014 Lecture 01 -1 21

Velocity from graph x Vav= Dx/Dt Q P Dx Dt As Dt gets small, Q approaches P and v dx/dt = slope of tangent at P instantaneous velocity t Physics 215 – Fall 2014 Lecture 01 -1 22

Interpretation • Slope of x(t) curve reveals vinst (= v) • Steep slope = large velocity • Upwards slope from left to right = positive velocity • Average velocity = instantaneous velocity only for motions where velocity is constant x t Physics 215 – Fall 2014 Lecture 01 -1 23

When does vav = vinst ? • When x(t) curve is a straight line – Tangent to curve is same at all points in time x t • We say that such a motion is a constant velocity motion – we’ll see that this occurs when no forces act Physics 215 – Fall 2014 Lecture 01 -1 24

Summary of terms • Positions: xinitial, xfinal • Displacements: Dx = xfinal - xinitial • Instants of time: tinitial, tfinal • Time intervals: Dt = tfinal - tinitial • Average velocity: vav = Dx/Dt • Instantaneous velocity: v = dx/dt • Instantaneous speed: |v| = |dx/dt| Physics 215 – Fall 2014 Lecture 01 -1 25

Reading assignment • Kinematics and graphs • Chapter 1 and 2. 1 - 2. 3 in textbook Physics 215 – Fall 2014 Lecture 01 -1 26