1. Shrinking Moon Explanation on next slide

4. Velocity Is a description of an object’s speed and direction. formula is the same as for speed Velocity= Distance in one direction Time

5. Speed vs. Velocity 1. How are speed and velocity similar? They both measure how fast something is moving. 2. How are speed and velocity different? Velocity includes the direction of motion and speed does not.

6. Speed vs. Velocity As a sailboat’s direction changes, its velocity also changes, even if it’s speed stays the same.

7. Resultant Velocities

8. ACCELERATION Acceleration is the change in velocity divided by the time it takes for the change to occur. This includes: speeding up, slowing down, and changing direction.

9. Examples

10. Calculating Acceleration Acceleration equals final velocity (V f ) minus initial velocity (V i ) divided by time. acc = V f -V i t

11. Let’s try one… A runner accelerates from 0 m/s to 3 m/s in 12 sec. What was the acceleration?

12. Step 1: Write the formula Acc = Vf - Vi t Step 2: Substitute in the numbers we know. Acc = 3m/s - 0m/s 12 s Step 3: Solve for the unknown variable. Acc = 3m/s =.25 m/s/s 12 s Step 4: Label your answer with the unit!

13. Acceleration Speeds Up If an object speeds up, the acceleration is in the same direction that the object is moving. The acceleration rate is a positive number.

14. Positive Acceleration When you speed up, your final speed will always be greater than your initial speed. Therefore, your acceleration will be a positive number or a positive acceleration rate.

15. Acceleration Slows Down If an object slows down, the acceleration is in the opposite direction that the object is moving. The acceleration rate is a negative number.

16. Negative Acceleration When you slow down, your final speed always will be less than your initial speed. Therefore, your acceleration will be a negative number or a negative acceleration rate.

17. Acceleration is also changing direction A bike that has changed direction has accelerated.

18. How does this motion look on a graph?

19. Data and graph illustrating constant speed. Data and graph illustrating constant speed.

20. Data and graph illustrating acceleration.

21. Graphing Motion