GRAPHING SPEED

Moving from Home

Graphing Variables – Recall

The dependent variable goes on the y-axis

The independent variable goes on the x-axis

The Variables The Graph

Independent VariableD

epen

dent

Var

iabl

e

The Speed Graph Setup

Distance is the dependent variable

Time is the independent variable

The Variables The Graph

TimeD

istan

ce

Graph setup = Formula

sp =dt

Speed & Slope (quick version)

Speed (d/t)= slope on a speed graph (rise/run)

Speed

Time

Distance

Steeper slope = faster speed

Changing slope = changing speed

Zero slope = 0 speed

Lower slope = slower speed

Speed Graphs & Slope (more)• Positive (+) slope• Forward motion

(away from start)

• Negative (-) slope• Backward motion

(toward start)

• Zero (0) slope (flat line)• No motion (speed = 0)

dist

t

t

dist

t

dist

Speed Graphs & Slope (still more)

• Straight lineso Constant speed

(speed doesn’t change)

• Lines curving upwardo Acceleration (speeding up)o Slope is getting steeper (↑speed)

• Lines curving to flato Deceleration (slowing down)o Slope is getting lower (flatter)

dist

t

dist

t

dist

t

dist

t

Calculating Speed from Slope

Rise–change in the graph on the vertical axis (Distance) Run–change in the graph on the horizontal axis (Time)

Speed =distance

timeSlope =

riserun

0 1 2 3 4 5 6 7 8 90

1

2

3

4

5

6

7

Speed (m/s)

Time (s)

Dis

tan

ce (

m)

Answers to Sample Questions What is the speed of the object from 0 –

3 s?

What is the speed of the object from 3 – 6 s?

What is the speed of the object from 6 – 8 s?

Speed (slope) =

Speed (slope) =

Speed (slope) =

Distance (rise)

Distance (rise)

Distance (rise)

Time (run)

Time (run)

Time (run)

=

=

=(0 – 6 m)(8 – 6 s)

=

( 6 – 6 m)( 6 – 3 s)

=

( 6 – 0 m)( 3 – 0 s)

=

6 m2 s

=

0 m3 s

=

6 m3 s

=

0 m/s

2 m/s

2 m/s