1. Bell work (9/16):
A freight train traveling with a speed of 18.0 m/s begins braking as it approaches a train yard.
The train’s acceleration while braking is – 0.33 m/s2.
What is the train’s speed after 23 seconds?

2. Free Fall
SWBAT analyze the motion of an object experiencing a constant acceleration due to gravity

3. Acceleration Practice Problems
A bicyclist accelerates at 0.89 m/s2 during a 5.0 s interval.  What is the change in the speed of the bicyclist?
If a rocket undergoes a constant total acceleration of 6.25m/s2, so that its speed increases from rest to about 750 m/s, how long will it take for the rocket to reach 750 m/s?
A dog runs with an initial speed of 1.5m/s on a waxed floor.  It slides to a stop with an acceleration of m/s2.  How long does it take for the dog to come to a stop?

4. Review Acceleration Rate at which velocity changes 0 s 1 s 2 s 3 s 4 s
0 m/s
4 m/s
8 m/s
12 m/s
16 m/s

5. Determining Acceleration from Data
Time
Velocity
0 min.
0 km/min
1 min.
8 km/min
2 min.
16 km/min
3 min.
24 km/min
4 min.
32 km/min
5 min. ?
Time
Velocity
0 hrs.
0 mph
2 hr.
10 mph
4 hrs.
20 mph
6 hrs.
30 mph
8 hrs.
40 mph
10 hrs. ?
What is the acceleration of these two data sets?
Predict the velocity at the final time for both data sets.

6. The acceleration of a raindrop that falls at constant velocity
a. is zero.
b. is directed downward.
c. decreases over time.
d. increases over time.
Answer: A

7. If a falling object gains 10 m/s each second it falls, its acceleration is
a. 10 m/s.
b. 10 m/s2.
c. directed upward.
d. steadily increasing.
Answer: B

8. Free Fall
Any object being acted on only by gravity is said to be in free fall
Do not encounter air resistance
All free falling objects accelerate downward at a rate of 9.8 m/s/s or
9.8 m/s2 (approx. 10 m/s2)

9. Free Fall
Any object being acted on only by gravity is said to be in free fall
Do not encounter air resistance
All free falling objects accelerate downward at a rate of 9.8 m/s/s or
9.8 m/s2 (approx. 10 m/s2)

10. Exit Ticket
On your personal index card, please answer the following question individually, showing work:
Falling objects drop with an average acceleration of 9.8 m/s2. If an object falls from a tall building, how long will it take before it reaches a speed of 49 m/s, if released from rest?

12. Bell work (9/17):
On a distant planet, a freely falling object has an acceleration of 20 m/s2. Calculate the speed that an object dropped from rest on this planet acquires in 1.5 seconds.

13. Free Fall – How Far?
The distance covered by an accelerating object is:
So, under free fall, when acceleration is 9.8 m/s2, the distance is:
________ m after 1 second?
________ m after 2 seconds?

14. Free Fall Practice Problems
An apple drops from a tree & hits the ground in 1.5 s. Calculate how far it falls. Neglect air resistance.
Calculate the vertical distance an object dropped from rest covers in 12s of free fall. Neglect air resistance.

15. Free Fall Practice Problems
Silver Level
Gold Level
A ball is dropped with a speed of 6 m/s from the top of a building. Find:
The velocity of the ball after 6 seconds.
How far the ball fell?
A dart leaves the barrel of a blowgun at a speed of v. The length of the blowgun barrel is L. Assuming that the acceleration of the dart in the barrel is uniform.
Show that the dart moves inside the barrel for a time of 2L/v.

16. Exit Ticket
On your personal index card, please answer the following question individually, showing work:
What is the distance covered of a freely falling object starting from rest after 4 seconds?

18. Bell work (9/18):
An airplane accelerates down a runway at 3.20 m/s2 for 32.8 seconds until is finally lifts off the ground. Determine the distance traveled before takeoff.
If you drop an object, its acceleration toward the ground is 10 m/s2. If you throw it down instead, would its acceleration after throwing be greater than 10 m/s2. Why or why not?

19. Pair Work (8 min.) Review HW from last night
Select one problem you would like Mr. C. to do for the entire class.

20. Free Fall Problem Assessment (10 min.)
To the right is the depiction of a boy throwing a red ball vertically in 1-D. Calculate/prove the following, showing your work where appropriate:
The velocity of the ball after 3 seconds is 0 m/s.
The height of the ball after 3 seconds.
The height of the ball after 6 seconds is 0 m.