1. Warm-Up 9/30/13 Your warm-up is on your table (Strobe Diagrams)
Read the directions to determine velocity.
ALSO, for each of the different strobe diagrams, decide if they show
Acceleration
Deceleration
Neither

2. Acceleration Section 11/3
Monday 9/30/13

3. Acceleration Acceleration is the rate of change of velocity.
Can be due to a change in direction or speed, as velocity depends on both!

4. Calculating Acceleration
Equation and Units
D = Change = FINAL - INITIAL
Dv = Final velocity – Initial velocity

5. Example Calculation
A Cessna Aircraft goes from 0 m/s to 60 m/s in 13 seconds. Calculate the aircraft’s acceleration.

6. Example Calculation 4.62 m/s/s
A Cessna Aircraft goes from 0 m/s to 60 m/s in 13 seconds. Calculate the aircraft’s acceleration.
4.62 m/s/s

7. The Cessna now decides to land and goes from 60 m/s to 0 m/s in 11 s
The Cessna now decides to land and goes from 60 m/s to 0 m/s in 11 s. Calculate the Cessna’s deceleration.

8. The Cessna now decides to land and goes from 60 m/s to 0 m/s in 11 s
The Cessna now decides to land and goes from 60 m/s to 0 m/s in 11 s. Calculate the Cessna’s deceleration.
m/s/s

9. What the Signs Mean (+ or -)
If your answer for acceleration is +
Velocity (speed) is increasing
Slowing down is happening less quickly (like letting up on the brake)
If your answer for acceleration is –
Velocity (speed) is decreasing
Speeding up is happening less quickly (quick off the line, and then accelerating slowly)

10. Graphing Acceleration
We can determine acceleration based on velocity- time graphs (distance-time graphs are for determining velocity)

12. Example What is the acceleration from t=0s to t=3s?
60/3= 20 m/s/s
What is the acceleration from
t=3 s to t=5s?
0/2 = 0 m/s/s
What is the acceleration from
t=8s to t=9s?
0-60/1 = -60 m/s/s

13. Free Fall
An object in freefall accelerates vertically toward the earth due to gravity
Negative because always DOWNWARD
Never stops existing
(the value doesn’t account for things like wind resistance)

14. Bottom Line: Downward acceleration in freefall is always the same!
Free Fall Diagram
Velocity= 0 m/s, Acceleration= -9.8
Bottom Line: Downward acceleration in freefall is always the same!

15. Your Job Finish the Acceleration worksheet (DUE tomorrow)
Please TURN IN: Moving Man Simulation from Friday
Tuesday-Thursday we are working on our Unit Project! It is counting as your test for the Motion unit.