Distance Time GraphsDistance Time Graphs

•Time is always plotted on x axis

•Distance is always plotted on y axis

•To figure average speed, divide distance by time

Distance-time graphsDistance-time graphs

40

30

20

10

0 20 40 60 80 100

4) Diagonal line downwards = returning to

start

3) Steeper diagonal line = faster the motion

1) Diagonal straight line = moving at

constant speed

2) Horizontal line =

Stopped, not moving

Distance

(meters)

Time/s

Distance – time GraphsDistance – time Graphs

•Line is curving upwards – shows increase in speed•It is accelerating.•Curving downwards – shows decrease in speed, •It is still accelerating – change in speed

40

30

20

10

0 20 40 60 80 1001) What is the speed during the first 20 seconds?

2) What is happening between 20 and 40 seconds?

3) How far is the object from the start after 60 seconds?

4) What is the speed during the last 40 seconds?

5) When was the object travelling the fastest?

Distance

(meters)

Time/s

How to calculate slopeHow to calculate slopeSlope =

y2 – y1

X2 - X1

• Rise divided by Run• 25- 5 = 20• 5- 0 5• Slope = 4 m/s

QuestionQuestion

• What does the slope of a distance vs. time graph show you about the motion of an object?

• It tells you the SPEED

QuestionQuestion

• Below is a distance vs. time graph for 3 runners. Who is the fastest?

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 35

Time (h)

Dis

tan

ce (

mi.

)

Bob

Jane

Leroy

Leroy is the fastest. He completed the race in 3 hours

Speed Time GraphsSpeed Time Graphs

•Time in plotted on X-axis•Speed or velocity is plotted on Y-axis•Shows acceleration

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6

Time (s)

Spee

d (m/

s)

Speed-time graphsSpeed-time graphs

80

60

40

20

0 10 20 30 40 50

Velocity

m/s

T/s

1) Upwards line = object is

accelerating

2) Horizontal line = speed is constant

3) Upwards line =

4) Downward line =

object is deceleratin

g

80

60

40

20

0

1) How fast was the object going after 10 seconds?

2) What is the acceleration from 20 to 30 seconds?

3) What was the deceleration from 30 to 50s?

4) How far did the object travel all together?

10 20 30 40 50

Velocity

m/s

T/s