Speed-Time Graphs

The skier's speed increased at a constant rate because the skier was moving down the hill with constant acceleration. Constant acceleration is represented on a speed–time graph by a straight line. The graph in Figure 16 is an example of a linear graph, in which the displayed data form straight-line parts. The slope of the line is the acceleration.

Constant negative acceleration decreases speed. A speed-time graph of the motion of a bicycle slowing to a stop is shown in Figure 17. The horizontal line segment represents constant speed. The line segment sloping downward represents the bicycle slowing down. The change in speed is negative, so the slope of the line is negative.

Figure 16 The slope of a speed time graph indicates acceleration. A positive slope shows that the skier's acceleration is positive.

Photo of a skier skiing downhill, moving faster due to the direction and slope. There is a chart off to the side of the photo depicting positive acceleration.

Figure 17 The horizontal part of the graph shows a biker's constant speed. The part of the graph with negative slope shows negative acceleration as the mountain biker slows to a stop.

Point of view photo of a person on a bicycle going downhill on a rustic bike path; this photo depicts negative acceleration, and a negative acceleration chart is off to the side of the photo.

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Table of Contents

Physical Science CHAPTER 1 Science Skills CHAPTER 2 Properties of Matter CHAPTER 3 States of Matter CHAPTER 4 Atomic Structure CHAPTER 5 The Periodic Table CHAPTER 6 Chemical Bonds CHAPTER 7 Chemical Reactions CHAPTER 8 Solutions, Acids, and Bases CHAPTER 9 Carbon Chemistry CHAPTER 10 Nuclear Chemistry CHAPTER 11 Motion CHAPTER 12 Forces and Motion CHAPTER 13 Forces in Fluids CHAPTER 14 Work, Power, and Machines CHAPTER 15 Energy CHAPTER 16 Thermal Energy and Heat CHAPTER 17 Mechanical Waves and Sound CHAPTER 18 The Electromagnetic Spectrum and Light CHAPTER 19 Optics CHAPTER 20 Electricity CHAPTER 21 Magnetism CHAPTER 22 Earth's Interior CHAPTER 23 Earth's Surface CHAPTER 24 Weather and Climate CHAPTER 25 The Solar System CHAPTER 26 Exploring the Universe Skills and Reference Handbook