文档介绍：Chap1-4 Describing Motion with Velocity vs. Time Graphs
1 The Meaning of Shape for a v-t Graph
Our study of 1-dimensional
kinematics has been concerned with
the multiple means by which the
motion of objects can be
represented. Such means include the
use of words, the use of diagrams,
the use of numbers, the use of
equations, and the use of graphs.
Lesson 4 focuses on the use of velocity vs. time graphs to describe motion.
As we will learn, the specific features of the motion of objects are
demonstrated by the shape and the slope of the lines on a velocity vs.
time graph. The first part of this lesson involves a study of the
relationship between the shape of a v-t graph and the motion of the object.
Consider a car moving with a constant, rightward (+) velocity - say of
+10 m/s. As learned in an earlier lesson, a car moving with a constant
velocity is a car with zero acceleration.
If the velocity-time data for such a car were graphed, then the resulting
graph would look like the graph at the right. Note that a motion described
as a constant, positive velocity results in a line of zero slope (a
horizontal line has zero slope) when plotted as a velocity-time graph.
Furthermore, only positive velocity values are plotted, corresponding to
a motion with positive velocity.
Now consider a car moving with a rightward (+), changing veloci