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Acceleration!. Chapter 9 Section 3. Acceleration. Let’s Review: What is Speed? Velocity? What is a Vector? Acceleration : RATE at which velocity changes Refers to INCREASING speed, DECREASING speed, or CHANGING direction . Is Acceleration a Vector?
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Acceleration! Chapter 9 Section 3
Acceleration Let’s Review: What is Speed? Velocity? What is a Vector? • Acceleration: RATE at which velocity changes • Refers to INCREASING speed, DECREASING speed, or CHANGING direction.
Is Acceleration a Vector? A softball accelerates when it is thrown, hit, or caught. What change in motion occurs in each example? Thrown- ball accelerates as it is thrown Hit- ball changes direction Caught- ball decelerates (negative acceleration) How can a car be accelerating if its speed is constant at 65 km/h?
The arrows are larger as the plane increases speed or accelerates…the arrows represent the vector quantity.
BRAIN BREAK! Acceleration is like…Because… Now, let’s play Gotcha!
Calculating Acceleration Final Velocity-Beginning Velocity Time Final Velocity Beginning Velocity Fv-Bv a = t Time
Example: As a roller coaster starts down a slope, its velocity is 4 m/s. But 3 seconds later, its velocity is 22 m/s in the same direction. What is its acceleration? Initial Velocity: 4 m/s Final Velocity: 22 m/s Time: 3 s Final Velocity – Initial Velocity/ Time 22 m/s – 4 m/s 3 s 18 m/s = 6 m/s/s or 6 m/s2 3 s
Graphing Acceleration • Speed vs. Time Graph • Upward means speed is increasing Line is straight means acceleration is constant • A horizontal line (flat) would mean that the object is moving at a constant speed. • Slope on a speed vs. time graph represents acceleration
Distance vs. Time Graph • Curved line means that the objects is accelerating (nonlinear). • During each second, the object traveled a greater distance than the second before. • Slope is speed and since slope is getting steeper and steeper, you can conclude that speed is also increasing…or that the object is accelerating.