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Unformatted text preview: s m 3.3 12s 40m 12s 10m 50m t x v = =-- = = 10m t 3.3 x s m f + = Chapter 2: Introduction to Kinematics The Constant Velocity Particle Model (CVP) Kinematics is the study of motion. In this chapter we will study constant velocity in one dimension. That means the object is moving with the same speed in a straight line. The line may be horizontal, vertical, or at an angle. When we call an object a particle, it means that the size or composition of the object is not an important factor in its behavior. In this unit we will build a model for motion of a particle at a constant velocity using three representations. You will learn to use graphical representations, motion maps and mathematical equations. Part 1: Vocabulary of motion Here is a quick look at some of the vocabulary of motion. Position : the location of an object. The variable for position is the letter x . To measure a position, we pick a spot, call it the origin (zero), and measure the distance from this spot to the object. Zero position may be anyplace one wants it to be. Distance : the length of the path an object moves. The variable for distance is the letter d . Displacement : The change in position of an object between two points. To find the displacement, the straight- line distance from the starting position to the final position is measured. The direction this line points is the direction of the displacement. The variable for change in position is x . The symbol is pronounced delta, and stands for change in. By definition, displacement is final position x f minus starting position x I or in the form of an equation i f x x x- = . Distance is a scalar quantity. Scalar quantities have only magnitude (an amount), direction is not important. Displacement is a vector quantity. Vector quantities have both magnitude and direction. In this chapter, since the objects are always moving in a straight line, we use directions like up and down, right and left, north and south, etc. The standard unit of distance and displacement is the meter (m), although many other units are used. Speed : how fast an object is moving or the rate of change in distance. The variable for speed is the letter v . Velocity : how fast and in what direction an object is moving or the rate of change in displacement. The variable for velocity is also the letter v . Most people use the terms velocity and speed interchangeably. To a physicist, they are different in that velocity has direction associated with it and speed does not. Velocity is a vector, and speed is a scalar. The direction of the objects velocity is the same as its displacement....
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- Spring '09