Plans for the Week and Assignments: 1. FRIDAY(09/04): Coordinate Systems, Properties of Vectors, Scalars. HW: Read Ch.3, pages 59-65 and solve prob. 4, 7, 14, 18, & 27 on pages 71-2. 2. TUESDAY(09/08): Lab on Addition of Vectors. HW: Complete lab report and write Abstract, due Friday. 3. WEDNESDAY(09/09): The Mathematics of Vectors. HW: Read pages 65-70 and solve prob. 29, 31, 33, 49, & 59 on pages 72-4. 4. THURSDAY(09/10): Review for Ch.3. All completed homework must be brought to class today in your binder to be checked. HW: Complete Review Handout. 5. FRIDAY(09/11): TEST on Ch.3 - Vectors. HW: Go to web-site for notes on Ch.4 - Motion in Two Dimensions. Very Important: If you have any questions or miss a class, see me before school (8:00 - 8:30 AM), during Lunch, or after school. Best to send an email to rpersin@fau.edu.
I. Vectors. Vectors are used to describe multi-dimensional quantities. Multi-dimensional quantities are those which require more than one number to completely describe them. Vectors, unlike scalars, have two characteristics, magnitude and direction. A vector is indicated by an uppercase letter either in boldface or with an arrow over the top. For example, A or  . Examples of vector quantities are: position in a plane, position in space, velocity, acceleration, and force. II. Scalars. Scalars are used to describe one- dimensional quantities, that is, quantities which require only one number to completely describe them. They have magnitude only. Direction does not apply. There are cases where scalars can be combined mathematically, but we will save that for later. Some examples of scalar quantities are: temperature, mass, time, volume, density, length, area, and energy. III. Vector Diagrams. Any vector can be resolved into perpendicular component vectors using sine and cosine functions. Actually, for all vector problems just remember SOHCAHTOA.
IV. Some Properties of Vectors. Two vectors are equal only if they have the same magnitude and direction. To find the opposite of a given vector just keep the same magnitude but point it in the opposite direction. ex. A - B = A + (-B) Vectors can also be expressed using polar coordinates (r , θ) specifying the length of the radius vector r , and the angle of rotation, Ø ("Phi"), from the positive x-axis. Additionally, in a two-dimensional coordinate system, vectors can be denoted using the unit vectors î and ĵ. Each unit vector has magnitude equal to 1, and they point in the x and y directions, respectively. We can easily add the third dimension, or z direction using unit vector k. V. Addition of Vectors Vectors can be added graphically using the head-to-tail method. You begin by drawing the first vector in a coordinate system, and then drawing the second vector from the endpoint of the first, and so on. Then you draw a single vector from the origin to the head of the last vector.
VI. Vector Subtraction.The vector difference works the same as vector addition except that we multiply the vector we are subtracting by -1. It is much like subtracting two numbers: A - B = A + (-B). The diagram below illustrates vector subtraction in the tip-to-tail style. The original B vector is shown as a dotted line.
VII. Multiplication of a Vector by a Scalar. A vector may be multiplied by a scalar by multiplying each of its components by that number. Notice that the vector does not change direction, only length. If A = (1,2) then 3A = (3,6). This is shown pictorially below.
Click Here to View a Vector Presentation To solve a vector problem in Physics use these steps: (i) read the problem and identify the given variables (ii) determine what you are asked to solve for (iii) draw a diagram and find the correct equation to use (iv) do the math (algebra/trig/calc) to isolate the unknown (v) substitute-in the given information and simplify.
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