1. CHAPTER 9 SECTION 3: Acceleration

2.  Acceleration is the rate at which velocity changes over time.

3.  An object accelerates if it’s speed, direction, or both change

4.  An increase in velocity is called positive acceleration

5.  A decrease in velocity is called deceleration or negative acceleration

6.  The faster the velocity changes, the greater the acceleration is.

7.  Average Acceleration = (Final Velocity – Starting Velocity) / Time

8.  (eg) A plane passes over point A at a velocity of 240M/sec North. Forty seconds later, it passes over point B at a velocity of 260M/sec North. What is the plane’s AVG. Acceleration? ave. acceleration = 260m/s - 240m/s = 0.5m/s² 40s

9.  Acceleration can be shown on a graph as velocity versus time.

10. Circular Motion Because the Earth rotates, you are accelerating because you are changing direction

11.  An object in a circular path is always changing direction, therefore it’s velocity is always changing, so it is accelerating.

12.  Acceleration in a circular path is called centripetal acceleration

13.  (eg) Ferris wheel, Moon’s orbit, blades of a fan or windmill.