1. Acceleration

2. Acceleration The rate at which velocity changes *** velocity is a combination of speed and direction. Acceleration can be change in speed, change in direction, or changes in both. Acceleration is a vector ***vector is a number that has magnitude and direction

3. Change in Speed This change may be due to either an increase or a decrease in speed Positive: increasing change in speed Negative: decreasing change in speed

4. Free Fall Movement of an object toward Earth solely because of gravity Due to change in speed Rate of change in speed is 9.8 meters per second per second (9.8 m/s 2 )

5. Changes in Direction Acceleration may be due to its direction constantly changing even though it is traveling at constant speed Ex: horse on a carousel A horse on the carousel is traveling at a constant speed, but it is accelerating because its direction is constantly changing.

6. Changes in Speed and Direction Sometimes motion is changing in both speed and direction at the same time Ex. Roller CoasterRoller Coaster

7. Constant Acceleration A steady change in velocity An airplane’s acceleration may be constant during a portion of its takeoff.

8. Calculating Acceleration Rate at which velocity changes V i is the initial velocity, v f is the final velocity, and t is total time. If the velocity increases, the acceleration is positive. If the velocity decreases, the acceleration is negative.

9. Calculating Acceleration 1. A ball rolls down a ramp, starting from rest. After 2 seconds, its velocity is 6 meters per second. What is the acceleration of the ball?

10. Calculating Acceleration 2. A car traveling at 10 m/s starts to decelerate steadily. It comes to a complete stop in 20 seconds. What is its acceleration?

11. Calculating Acceleration 3. An airplane travels down a runway for 4.0 seconds with an acceleration of 9.0 m/s 2. What is its change in velocity during this time?

12. Calculating Acceleration 4. A child drops a ball from a bridge. The ball strikes the water under the bridge 2.0 seconds later. What is the velocity of the ball when it strikes the water?

13. Acceleration Graphs Acceleration is the slope of a speed-time graph The slope is change in speed divided by time

14. Speed VS Time The skier’s acceleration is positive. The acceleration is 4 m/s 2.

15. Speed VS Time The biker moves at a constant speed and then slows to a stop.

16. Distance VS Time Accelerated motion is represented by a curved line on a distance-time graph. In a nonlinear graph, a curve connects the data points that are plotted.

17. Instantaneous Acceleration Instantaneous acceleration is how fast a velocity is changing at a specific instant.