Graphical Representation of Motion in One Dimension (Part One)
Position–Time Graph
First: Summary:
► 𝑥-axis → Time (𝑡)
𝑦-axis → Position (𝑥)
► If the graph is horizontal → the object is at rest.
If the graph is not horizontal → the object is in motion.
► If the graph slopes upward → the object is moving eastward.
If the graph slopes downward → the object is moving westward.
► If the graph is a straight line → the velocity is constant (𝑎 = 0).
If the graph is a curved line → the velocity is changing (𝑎 ≠ 0).
► If the graph is a straight line → the magnitude of the velocity equals the slope of the graph.
If the graph is a curved line:
● The instantaneous velocity equals the slope of the tangent at that instant.
● The average velocity equals the slope of the straight line connecting the initial point and the
final point.
Main idea: The slope of a position–time graph represents velocity.
x (m)
Δy
slope =
Δx
= velocity
t (s)
Position–Time Graph
First: Summary:
► 𝑥-axis → Time (𝑡)
𝑦-axis → Position (𝑥)
► If the graph is horizontal → the object is at rest.
If the graph is not horizontal → the object is in motion.
► If the graph slopes upward → the object is moving eastward.
If the graph slopes downward → the object is moving westward.
► If the graph is a straight line → the velocity is constant (𝑎 = 0).
If the graph is a curved line → the velocity is changing (𝑎 ≠ 0).
► If the graph is a straight line → the magnitude of the velocity equals the slope of the graph.
If the graph is a curved line:
● The instantaneous velocity equals the slope of the tangent at that instant.
● The average velocity equals the slope of the straight line connecting the initial point and the
final point.
Main idea: The slope of a position–time graph represents velocity.
x (m)
Δy
slope =
Δx
= velocity
t (s)
