1. DO NOW (SILENT & INDEPENDENT):
According to Google maps, one can get from Ms. Poole’s house to the Georgia Dome (about 3 miles) in 10 minutes. What average speed are the map makers assuming we travel?
(Show ALL work!)
5 minutes

2. DO NOW (SILENT & INDEPENDENT):
According to Google maps, one can get from Ms. Poole’s house to the Georgia Dome (about 3 miles) in 10 minutes. What average speed are the map makers assuming we travel?
AVG SPEED = distance / time
s = d/t  s = 3 miles/ 10 minutes
 0.3 mi/min

3. SWBAT CALCULATE ACCELERATION & VELOCITY (Lab coming soon!)
OBJECTIVE
SWBAT CALCULATE ACCELERATION & VELOCITY (Lab coming soon!)

4. Key terms:
Acceleration – rate of change in velocity measured in m/sec2
Velocity – includes speed of object and direction of its motion
Instantaneous speed – speed at any given point in time

5. Sometimes objects don’t travel at a constant velocity but rather speed up or slow down.
Acceleration is the CHANGE (Δ)of an objects velocity over time.
Note – acceleration is ONLY used in reference to velocity, NOT SPEED!!

6. We typically think of acceleration as something speeding up (positive acceleration)
BUT
It can also be used to describe something slowing down (negative acceleration)

7. VIDEO
ACCELERATION

8. Diagram A – each car represents position of an object at a different time
Equal distances apart, therefore traveling at a constant velocity.
Since velocity is not changing, acceleration is ZERO

9. Diagram B – cars become further apart
Because they are covering more distance in same time period, velocity is increasing.
Acceleration is POSITIVE because the displacement to the right is increasing.
Remember –
displacement = final position – initial position

10. Diagram C – cars become closer as time passes
Because they are covering less distance in same time period, velocity is decreasing.
Acceleration is NEGATIVE because displacement to right is decreasing
Remember –
displacement = final position – initial position

11. Like velocity – the acceleration of an object can change in two ways.
Either the speed can increase or decrease, or the direction can change.

12. DETERMINING ACCELERATION
THE FOLLOWING EQN IS USED FOR ACCELERATION:
a = (vf – vi) / t
Acceleration = (final velocity – initial velocity)/time

13. Along a north straightaway a racecar’s velocity changes from 0 m/s to 50 m/s in 5 seconds. What is the car’s acceleration?

14. Along a north straightaway a racecar’s velocity changes from 0 m/s to 50 m/s in 5 seconds. What is the car’s acceleration?
Initial velocity (vi) is 0 m/s.
Final velocity (vf) is 50 m/s.

15. Along a north straightaway a racecar’s velocity changes from 0 m/s to 50 m/s in 5 seconds. What is the car’s acceleration?
Initial velocity (vi) is 0 m/s.
Final velocity (vf) is 50 m/s.
a= (50 m/sec – 0 m/sec) / 5 sec

16. Along a north straightaway a racecar’s velocity changes from 0 m/s to 50 m/s in 5 seconds. What is the car’s acceleration?
Initial velocity (vi) is 0 m/s.
Final velocity (vf) is 50 m/s.
a= 10 m/sec 2 north

17. Turn over your notes!
1-6 Short answer.
Let’s talk about it!

18. Teams

22. 8/27/14 1. Which of the following is NOT an example of acceleration?
A car changing direction at a constant speed
A car speeding up
A car slowing down
A ball rolling down a hill at a constant speed

23. A roller coaster car rapidly picks up speed as it rolls down a slope
A roller coaster car rapidly picks up speed as it rolls down a slope. As it starts down the slope, its speed is 4 m/s. But 3 seconds later, at the bottom of the slope, its speed is 22 m/s. What is its average acceleration?

24. A cyclist accelerates from 0 m/s to 8 m/s in 3 seconds
A cyclist accelerates from 0 m/s to 8 m/s in 3 seconds. What is his acceleration ? Is this acceleration higher than that of a car which accelerates from 0 to 30 m/s in 8 seconds?

25. A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds. Find the car’s average acceleration.

26. A lizard accelerates from 2 m/s to 10 m/s in 4 seconds
A lizard accelerates from 2 m/s to 10 m/s in 4 seconds. What is the lizard’s average acceleration?

27. A runner covers the last straight stretch of a race in 4 s
A runner covers the last straight stretch of a race in 4 s. During that time, he speeds up from 5 m/s to 9 m/s. What is the runner’s acceleration in this part of the race?

28. You are traveling in a car that is moving at a velocity of 20 m/s
You are traveling in a car that is moving at a velocity of 20 m/s. Suddenly, a car 10 meters in front of you slams on it’s brakes. At that moment, you also slam on your brakes and slow to 5 m/s. Calculate the acceleration if it took 2 seconds to slow your car down.

29. A ball is dropped from the top of a building
A ball is dropped from the top of a building. After 2 seconds, it’s velocity is measured to be 19.6 m/s. Calculate the acceleration for the dropped ball.