 # Acceleration! Chapter 9 Section 3.

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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.

Acceleration is like…Because…
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

Final Velocity – Initial Velocity/ 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 = m/s/s or 6 m/s2

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.

THE END!