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Speed Graphs. Slide Show #3a. Why graphs?. Describing motion can be hard to do with words. Sometimes graphs help make motion easier to see. Distance-Time Graphs. Also known as speed graphs. Time is always plotted on the x-axis! Distance is always plotted on the y-axis.
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Speed Graphs Slide Show #3a
Why graphs? • Describing motion can be hard to do with words. • Sometimes graphs help make motion easier to see.
Distance-Time Graphs • Also known as speed graphs. • Time is always plotted on the x-axis! • Distance is always plotted on the y-axis.
I’m NOT moving! • If an object is not moving, a horizontal line is shown on the distance time graph. • As time goes by, distance doesn’t change. • Object is not moving. (see blue line)
Cruise Control! • There is a steady increase in distance with time. • You are in CONSTANT speed • It is shown as a straight line with a slope! (not flat).
Who’s faster? • Both lines are straight and sloped. • Both lines have constant speed. • But the yellow line is faster than the blue line. • The yellow line is steeper than the blue line. • The steeper the line, the faster the speed!
Step on it! • The line in this graph is curving upwards. • The speed is increasing (getting steeper). • It is accelerating!
Ewww! Numbers Yellow speed = 30 meters/10 seconds = 3 m/s Blue speed = 20 meters/20 seconds = 1 m/s
Here is another one! • Blue Line’s speed is • 100 m/10s = 10 m/s • Aqua Line’s speed is • 50 m/10s = 5 m/s • Purple Line’s speed is • 150 m/20s = 7.5 m/s Notice the purple line slope’s downward. This means it returned back to start point!
Check out the Motion Man! • If it acts up, just click restart. • Choose “one” for number of graphs. • Top graph should read “distance” • And now, The Moving Man!