PHYSICS 6A Lecture Notes - Lecture 2: Coordinate System, One Direction
Document Summary
Mechanics is the study of the motion of objects, typically divided into two parts: Kinematics: mathematical description of how objects move. Dynamics: motion of objects as influenced by forces. Why objects move and how they move. Describing the position of an object or the motion of an object in space requires defining a reference frame and specifying its location. Coordinate system: specifies a fixed reference point (origin), a set of axes and instructions on how to label points in space. Cartesian (rectangular) coordinates specify x, y, and z location as (x, y, z) position. One dimension motion: x-axis for horizontal direct and y-axis for up-down motion. Presently we will consider objects as massless with no extent. Distance (d): length of a path followed by an oject. Displacement ( x): the object"s change in position. Distance and displacement are not the same quantities. A person walks to the east 70m (positive x axis), then 30m west (negative x axis)
