SPEED

Speed Speed is the

distance an object moves in a particular amount of time.

OR How far you go

and how long it takes to get there.

How to find the speed of an object or a person:

Calculate Speed Distance /Time (distance divided by

time) Try some: calculate the speed

Distance ->Time

1m 2m 3m 4m 6m

1 hour

2 hours

3 hours *

AnswersDistance ->Divided byTime

1m 2m 3m 4m 6m

1 hour 1m/h 2m/h 3m/h 4m/h 6m/h

2 hours 0.5m/h 1m/h 1.5m/h 2m/h 3m/h

3 hours 0.33m/h 0.66m/h 1m/h 1.33m/h 2m/h *

Average Speed

Most objects do not move at constant speeds for very long.

Race cars change speeds many times during the race: slower around the curves and faster on the straight places.

Graphing Motion

You can show the motion of an object on a line graph.Time is on the X-axis (horizontal) and distance is on the Y-axis (vertical). The 2 numbers are called coordinates of the point.

Moving Man: http://www.mste.uiuc.edu/Murphy/MovingMan/MovingMan.html

Graphing Constant Motion Constant motion is motion that does

not change. That means the object is neither

speeding up or slowing down. Constant motion is shown as a straight

line on a graph:Motion: Constant Motion

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Motion: Constant Motion

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Constant Motion Graph This graph shows

constant motion because the slope of the line does not change. The slope of the line

can be used to determine the speed of the object.

The change in distance for every minute on this graph is constant.

Motion: Constant Motion

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Speed = distancetime

In this graph Speed = 2 m/min.

Constant Motion continued This graph also

shows constant motion because the slope of the line does not change. The slope of this line

does not change either.

The distance on this graph stays the same.

Speed = d/t = 0/10 = 0 m/min

So what can be said about the motion?

The object is not moving.

Motion: Constant Motion

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Change in Motion When looking at

a graph, you can tell when motion changes because line is not straight. Change in motion

can be seen as a change in the straight line or as a curved line.

Motion: Change in Motion

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Motion: Change in Motion

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Change in Motion continued In this graph, there

are three different types of constant motion. Motion is constant

between minutes 0 and 4, 4 and 6, and 6 and 10.

Even though between these points motion is constant, the overall motion changes.

Motion: Change in Motion

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Change in Motion continued In this graph, the

motion is not constant between any two points. Motion is constantly

changing. The curve of this

graph shows acceleration.

Acceleration is the increase or decrease in speed.

Motion: Change in Motion

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This graph shows increasing speed because the curve goes upward.

The speed before turning around is quicker because the _______ is greater than after turning around.

Change in Direction On a motion graph,

you can tell when the object reverses direction because the distance from the starting point becomes less. By looking at the

slopes of the two lines, what can be said about the speed before compared to the speed after turning around?

Motion: Change in Direction

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SlopeSlope

Line graphs can show all kinds of information.

Look at the axis labels before you analyze the information.

Time GraphConnect the dots and analyze the graph

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Lap 1 Lap 2 Lap 3 Lap 4

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2.52.5

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Analysis: Time Graph This is a graph showing time for 2 runners

in the 600 m race. It shows that George ran 2.5 minutes for the first lap, 3 minutes for the 2nd lap, 3.5 minutes for the 3rd lap, and 3 minutes for the 4th lap. Nina ran 3 minutes for the 1st, 3.5 for the 2nd, 3 for the 3rd, and 2.5 for the 4th. To calculate the average speed, take the total distance and divide by the total time.

George’s average speed: 50 m/min Nina’s average speed: 50 m/min