Linear Motion of Objects on Distance-Time Graphs
Distance vs. Time Graphs • Distance vs. time graphs tell you how far something has traveled in a certain time. Object at Rest
y-axis has the dependent variable 3.50 3.00 2.50 2.00 1.50 1.00 distance (meters) 0.50 0.00 0.00
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x-axis has the independent variable
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Object at Rest • The graph for an object at rest is flat. • After each time the object is at the same distance meaning it has not moved.
Object at Rest 3.50 3.00 2.50 2.00 1.50 1.00 distance (meters) 0.50 0.00 0.00
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3.00 time (seconds)
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Constant Speed • An object at a constant speed is a diagonal straight line. • The distance increases the same amount from point to point.
Constant Speed 16.00 14.00 12.00 10.00 8.00 6.00 4.00 distance (meters) 2.00 0.00 0.00
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Accelerating Object (Speeding Up) • The shape of the graph for an accelerating object is curved. • The object covers more and more distance between each point if it is speeding up.
Accelerating Object 200.00 150.00 100.00 50.00 distance (meters) 0.00 0.00
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Negative Acceleration (Slowing Down) • For an object with negative acceleration the graph is curved and is getting flatter. • The object goes less distance from point to point.
Negative acceleration 200.00 180.00 160.00 140.00 120.00 100.00 80.00 60.00 40.00 (meters) distance 20.00 0.00 0.00 1.00
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Comparision of Speed • When comparing speed, the line with the steeper slope has a greater speed. • A line with a greater slope covers more distance from point to point.
Comparison of Speed 16 14 12 10 8 6 4 distance (meters) 2 0 0
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Acceleration Comparison • When comparing acceleration, the line that is curved the most has the greatest acceleration. • A line that is curved more covers more distance from point to point.
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3 5 0 . 0 0
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1 0 0 . 0 0 distance (meters) 5 0 . 0 0
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Displacement Graphs • Displacement graphs show displacement vs. time. • Displacement graphs tell you about traveling in different directions. • A positive slope is traveling away from the start. • A negative slope is traveling back to the start. • A flat line is an object that is not moving.
Direction Comparison • A displacement of 0 is equal to the where you started from. • Each point tells you how far you are from where you started. • At 4 hours the object represented by the square turned around and went back to the starting point.
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displacement (kilometers) 0
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Change of direction
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2 0 0
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1 6 0 S e r ie s 1 1 4 0 S e r ie s 2 1 2 0 S e r ie s 3 1 0 0
S e r ie s 4 S e r ie s 5
8 0
S e r ie s 6 6 0 S e r ie s 7 displacement (no units) 4 0
2 0
0 0
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t im
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in u t e s )
1 0 0
1 2 0
1 4 0
Story Graph Explanation • At first the object is traveling at a fairly constant velocity, away from the starting point. (Series 1) • Then it turns and goes at a constant velocity back towards the starting position. (Series 2) • It changes directions again and goes away from the starting point at about the original constant velocity. (Series 3) • From about 55 minutes to 75 minutes it moves at a slower constant velocity. (Series 4) • From about 75 minutes to about 85 minutes the object does not move. (Series 5) • From about 85 to 110 minutes it accelerates in a positive direction. (Series 6) • From about 95 minutes until about 110 minutes its velocity is about the same as the original velocity and fairly constant. (Series 7)