2 Acceleration Let’s Review: What is Speed? Velocity? What is a Vector? Acceleration: RATE at which velocity changesRefers to INCREASING speed, DECREASING speed, or CHANGING direction.
3 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 thrownHit- ball changes directionCaught- ball decelerates (negative acceleration)How can a car be accelerating if its speed is constant at 65 km/h?
4 The arrows are larger as the plane increases speed or accelerates…the arrows represent the vector quantity.
6 Acceleration is like…Because… BRAIN BREAK!Acceleration is like…Because…Now, let’s play Gotcha!
7 Calculating Acceleration Final Velocity-Beginning VelocityTimeFinal VelocityBeginning VelocityFv-Bva =tTime
8 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/sFinal Velocity: 22 m/sTime: 3 sFinal Velocity – Initial Velocity/ Time22 m/s – 4 m/s3 s18 m/s = m/s/s or 6 m/s2
9 Graphing Acceleration Speed vs. Time GraphUpward means speed is increasingLine is straight means acceleration is constantA horizontal line (flat) would mean that the object is moving at a constant speed.Slope on a speed vs. time graph represents acceleration
10 Distance vs. Time GraphCurved 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.