Physics 111 mechanics lecture 1

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Physics 111 mechanics lecture 1

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Physics 111: Mechanics Lecture Dale E Gary NJIT Physics Department Introduction    Physics 111 – Course Information Brief Introduction to Physics Chapter – Measurements (sect 16)       Measuring things Three basic units: Length, Mass, Time SI units Unit conversion Dimension Chapter – Vectors (sect 1-4)      Vectors and scalars Describe vectors geometrically Components of vectors Unit vectors Vectors addition and subtraction January 22-25, 2013 Course Information: Instuctor  Instructor: Prof Dale Gary Office: 101 Tiernan Hall  Office hours: 10:00-11:00 am Tues.,Thurs Telephone: 973-642-7878  Email: dgary@njit.edu  Website: http://web.njit.edu/~gary/111  January 22-25, 2013 Course Information: Materials See course web page for rooms and times for the various sections: Sec 014, 016, 018  Primary Textbook: “NJIT Physics 111 Physics for Scientists and Engineers”, 8th Edition, by Serway and Jewett  Lab Material: “Physics Laboratory Manual ”  Website: http://web.njit.edu/~gary/111  January 22-25, 2013 Course Information: Grading  Common Exams (17% each, 51% total)        Common Exam 1: Monday, February 25, 4:15 - 5:45 pm Common Exam 2: Monday, March 25, 4:15 - 5:45 pm Common Exam 3: Monday, April 15, 4:15 - 5:45 pm Final Exam (29%) Lecture/Recitation Quiz (8%) Homework (12%) Final Letter Grade A B+ B C+ C D F 85+ 80-84 70-79 65-69 55-64 50-54 < 50 January 22-25, 2013 Course Information: Homework  Homework problem assignment: WebAssign (purchase with textbook)  WebAssign Registration, Password, Problems: http://www.WebAssign.net   Class Keys: All sections: njit 0461 6178 HW1 Due on Jan 31, and other homeworks due each following Thursday January 22-25, 2013 Classroom Response Systems: iClickers   iClicker is required as part of the course  Similar to requiring a textbook for the course  Can be purchased at the NJIT bookstore  Cannot share with your classmate iClicker use will be integrated into the course  To be used during most or all lectures/discussions  iClicker questions will be worked into subject matter  Some related issues (“My iClicker doesn’t work”, or “I forgot my iClicker.”) More later January 22-25, 2013 How will we use the clicker?  I pose questions on the slide during lecture  You answer using your i-clicker remote  Class results are tallied  I can display a graph with the class results on the screen  We discuss the questions and answers  You can get points (for participating and/or answering correctly)! These will be recorded (e.g., for quizzes and attendance) January 22-25, 2013 Example: What is the Most Advanced Physics Course You Have Had? A High school AP Physics course B High school regular Physics course C College non-calculus-based course D College calculus-based course (or I am retaking Phys 111) E None, or none of the above January 22-25, 2013 Physics and Mechanics   Physics deals with the nature and properties of matter and energy Common language is mathematics Physics is based on experimental observations and quantitative measurements The study of physics can be divided into six main areas:        Classical mechanics – Physics I (Phys 111) Electromagnetism – Physics II (Phys 121) Optics – Physics III (Phys 234, 418) Relativity – Phys 420 Thermodynamics – Phys 430 Quantum mechanics – Phys 442 Classical mechanics deals with the motion and equilibrium of material bodies and the action of forces January 22-25, 2013 Properties of Vectors Equality of Two Vectors  Two vectors are equal if they have the same magnitude and the same direction  Movement of vectors in a diagram  Any vector can be moved parallel to itself without  Negative Vectorsbeing affected   Two vectors are negative if they have the same magnitude but are 180° apart (opposite directions)     A  A = −B; A + −A = B ( ) January 22-25, 2013 Adding Vectors     When adding vectors, their directions must be taken into account Units must be the same Geometric Methods  Use scale drawings Algebraic Methods  More convenient January 22-25, 2013    Adding Vectors Geometrically (Triangle Method)  Draw the first vector A with the appropriate length and in the direction specified, with respect to a coordinate  system Draw the next vector B with the appropriate length and in the direction specified, with respect to a coordinate system  whose origin is the end of A vector and parallel to the coordinate A system used for : “tip-to-tail”  The resultant is drawn from A  of to the end of the origin the lastBvector   A+ B  A January 22-25, 2013  B Adding Vectors Graphically When you have many vectors, just keep repeating the process until all are included  The resultant is still drawn from the origin of the first vector to the end of the last vector    A+ B    A+ B +C   A+ B January 22-25, 2013     Adding Vectors Geometrically (Polygon Method)   A Draw the first vector with the appropriate length and in the direction specified, with respect  to a coordinate system B Draw the next vector with the appropriate length and in the direction specified, with respect to the same coordinate system Draw a parallelogram   is drawn  The resultant as a diagonal A + Bfrom = Bthe + Aorigin  A+ B  B  A January 22-25, 2013 Vector Subtraction  Special case of vector addition  Add the negative of the subtracted vector  B r r r r A − B = A + −B ( )  Continue with standard vector addition procedure  A   A− B  −B January 22-25, 2013 Describing Vectors Algebraically Vectors: Described by the number, units and direction! Vectors: Can be described by their magnitude and direction For example: Your displacement is 1.5 m at an angle of 25 Can be described by components? For example: your displacement is 1.36 m in the positive x direction and 0.634 m in the positive y direction January 22-25, 2013 Components of a Vector   A component is a part It is useful to use rectangular components These are the projections of the vector along the xand y-axes a cos(90 − θ ) 90−θ θ = a sin θ a cos θ January 22-25, 2013 Components of a Vector θ  The x-component of a vector is the projection along theAx-axis Ax = A cos θ cos θ = x A  The y-component of a y projection vector is Athe Ay = A sin θ sin θ = along theAy-axis    A = AxThen, + Ay    A = Ax + Ay January 22-25, 2013 Components of a Vector The previous equations are valid only if θ is measured with respect to the x-axis  The components can be positive or negative and will have the same units as the original θ=0, Ax=A>0, Ay=0 vector  Ax < Ay > Ax > Ay θ> Ax < Ay < Ax > Ay < θ=45°, Ax=A cos 45°>0, Ay=A sin 45°>0 θ=90°, Ax=0, Ay=A>0 θ=135°, Ax=A cos 135°0 θ=180°, Ax=−A

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Mục lục

  • Physics 111: Mechanics Lecture 1

  • Introduction

  • Course Information: Instuctor

  • Course Information: Materials

  • Course Information: Grading

  • Course Information: Homework

  • Classroom Response Systems: iClickers

  • How will we use the clicker?

  • Example: What is the Most Advanced Physics Course You Have Had?

  • Physics and Mechanics

  • Classical Mechanics

  • Chapter 1 Measurement

  • Type Quantities

  • SI Unit for 3 Basic Quantities

  • Fundamental Quantities and SI Units

  • Why should we care about units?

  • SI Length Unit: Meter

  • SI Time Unit: Second

  • SI Mass Unit: Kilogram

  • PowerPoint Presentation

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