Motion Plots I

When physicists want detailed information about an object's movement, they gather data about it every second or millisecond. Sometimes, they gather the displacement (distance and direction from a starting point) at each moment in time, and other times, it is more useful to record the object's velocity.

The data collected is then transformed into a visual representation, with the independent variable, time, on the x-axis and either the object's distance and direction or its velocity on the vertical axis. This plot, a snapshot of the object's motion, is a powerful tool that brings abstract concepts to life. But the real magic lies in the slope of a motion plot, which holds even more information, waiting to be deciphered.

Here's how it works. You'll probably remember that the slope of any plot is ΔY/ΔX. Therefore, the slope of a displacement vs time plot at any given time would tell you about the object's velocity (Δd/Δt) during the interval you are concerned with. On the other hand, the slope of a velocity vs time plot during a time interval would reveal the object's acceleration. This is because acceleration is ΔV/Δt.

Video Instruction

showmethephysics.com

Enduring Understanding

Fill in the Blank Notes

B) Motion Plots

(a.k.a. Motion Diagrams) — 2nd way to describe motion

Position vs. Time Plot

Movement in a Straight Line

Fill in the position at each time from the plot above.

Position (m)	Time (sec)
?	0
?	2
?	4
?	6
?	8

Position (m)	Time (sec)
0	0
5	2
10	4
15	6
18.3	8

Speed From the Plot

Speed from 0 to 2 seconds?

Speed from 2 to 4 seconds?

Speed from 4 to 6 seconds?

Does the object travel faster or slower from 6 to 8 seconds?

Compare speed from 6 to 8 sec with speed from 8 to 9 sec.

What kind of motion produced this plot?

Equations