One Dimensional Kinematics Chapter 2 One Dimensional Kinematics

Kinematics From the Greek kinema, meaning motion, as in cinema This chapter focuses on one dimensional motion only (motion in straight lines; to the left or right, up or down, east or west and so on) For the next several chapters objects will be considered point particles

2.1 Position, Distance, Displacement The first step to describing motion is to set up a coordinate system that defines position.

2.1 Position In this coordinate system x = 0 is the origin An arrow indicates the positive direction (the direction which x increases) In figure 2-1 a person walks from an initial or starting position xi to a final position xf Notice that x = 0 does not always have to be the same as xi

2.1 Distance Distance = the total length of travel Si unit is the meter (m) Suppose you leave your house, drive to the grocery store, and then return home. Use the following figure to determine your distance:

2.1 Distance 4.3 miles to the store, then 4.3 miles for the return trip is a distance of 8.6 miles. In a car, the distance traveled is measured by the odometer. Distance is always positive, it does not depend on direction of travel.

2.1 Displacement Displacement = change in position which is the final position – the initial or starting position Shorthand for the change is position is: Dx In the previous example of the trip from your house to the grocery store the distance was 8.6 miles. However the displacement is 0. That’s because your starting or initial position is the same as the final position.

2.1 Homework Conceptual Questions 1-4 on page 46 Section 2-1 Problems 1-6 on page 47