Review Speed Speed The measure of how fastslow something moves a particular distance over a given amount of time It can then be calculated using the following formula vdt How do you graph speed ID: 701838
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Slide1
Distance-Time Graphs
2016-2017Slide2
Review - Speed
Speed:
The measure of how fast/slow something moves a particular distance over a given amount of time.
It can then be calculated using the following formula:
v=d/tSlide3
How do you graph speed?
Graphs are always set up the same way:
Y - axis
X- axisSlide4
Distance - Time Graphs
On a distance time graph, the distance will always be the dependent variable on the y- axis
.
Time is the independent variable and will always be placed on the x-axis.
Y - axis
X- axisSlide5
Lines on the Graphs
The lines on the graphs can tell you many different things. For example:
The
slope of a line
(steepness)
can tell you speed
.
If the slope is steep (more vertical) then the speed is fast.
If the slope is flatter (more horizontal) then the speed is slow.If the
line is completely flat
or horizontal then the object has
no speed or is stopped
.Slide6
Examples of distance-time graphs
FAST
STOPPED
SLOWSlide7
Other things we can learn from a graph:
We
can also show the direction
the object is traveling. The
point on the graph where the x and y axis meet is the reference point
or where the object’s home base is located (their starting point).
If the
arrow or line is pointing away or moving away from the x axis then the object is moving away from their reference point
or starting point.If the arrow or line is pointing toward or moving toward the x axis then
the object is moving back to the reference point.
Slide8
Leaving and coming back: Slide9
Speeding up and Slowing down
The object is speeding up and has
positive acceleration.
The object is slowing down and has
negative acceleration
.Slide10
Practice reading graphsSlide11
Determining Speed from a graph
V=d/t
Think of the graph in sections divided by each line segment
Then determine the total distance for the line segment you are looking at.
Then determine the total time for that segment.
Finally, use the equation to determine speed of the line segment.
Example: the object traveled a total distance of 25 m for the first segment. It took the object 20 seconds. v=d/t v=25/20 v= 1.25 m/sSlide12
Practice
Calculate the speed for last line segment:
Distance traveled = 25 m
Time = 10 sec
v=d/t 25/10
2.50 m/sec
Was the object moving faster or slower than when they started?Slide13
Practice on your own:
Calculate the speed for the first segment.
Calculate the speed for the third segment.Slide14
Graphs and Stories
This object left the reference point at a fast constant pace.
They then stopped for a brief period of time.
Finally they began to move again but at a slower rate.Slide15
Example with stories
Joe left home at a moderate constant speed. He realized that he forgot his wallet and turned around to go home to get it. However, while walking back he realized it was in his pocket so he turned around to head back to his friend’s house. He picked up his pace a little to help make up some lost time. When he got to his friend’s house they stayed to watch a movie.Slide16
You Practice writing a story
Distance (m)