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Mechanics Kinematics and Forces

Important things to remember 1) Units – Every numerical quantity must have units associated with it!! 2)Significant Figures – Important to show how precisely you know a measured quantity or a quantity calculated from measurements. You should be using the correct number of significant figures at all times. 3)Problem Solving Steps: a)Draw a Picture. b)Choose your reference frame. c)Identify known quantities. d)Identify unknown quantities. e)Identify equations that can be used to model this specific situation. f)Solve the selected equation(s) for an unknown quantity. g)Check numerical answer – for calculation errors. h)Check units – use dimensional analysis. i)Check significance of numerical value – Does it make sense? Make sure you understand the problems you are solving. It is not enough to determine a numerical value. Try to describe your reasoning in words. Ask yourself “why?” at each step.

CH 1: Vectors

Vector – quantity that has size and directional information. Magnitude – size of quantity, described by the length of the vector. Direction – Orientation of vector, described by an arrow.  l  is often used as a numerical description of direction. A vector is drawn to represent a quantity within a specific coordinate system. There are three common coordinate systems, but these are by no means the only possible coordinate systems. The choice of which coordinate system you will be using is up to you. You should choose a coordinate system such that it simplifies the solution to the problem. You can always transform a vector from one coordinate system to another. Common Coordinate Systems Rectangular – Cartesian – x, y, z Cylindrical – r, , z Spherical – r, ,  This is the coordinate system we will typically use. In 2D you have plane polar, which uses r and . = V Vector Notation Magnitude of a vector