1. BELLWORK 10/11/17
NB: Write “IN” and today’s date. Answer the following in complete sentence(s):
What does acceleration mean to you?
What 2 factors does velocity include? Speed and direction! In science acceleration can be applied to both increases and decreases in speed.
Acceleration is the rate of change in velocity.

3. “Through” Calculating Average Acceleration
The formula for calculating average acceleration is:
Acceleration (a) = final velocity (vf) – initial velocity (vi) time (sec)
Standard Units of acceleration:
Meters per second per second
m/s/s OR m/s2
Velocity is measured in meters per second and time is measured in seconds. So, acceleration is measured in meters per second per second. Or meters per squared.

4. Calculating Acceleration
A jet starts at rest at the end of a runway and reaches a speed of 80 m/s in 20 s. What is its acceleration?
What is the final velocity? What is the initial? What is the total time?

5. Calculating Acceleration
A jet starts at rest at the end of a runway and reaches a speed of 80 m/s in 20 s. What is its acceleration?
Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
a = 80 m/s – 0 m/s
20 sec
a=4m/s/s
What is the final velocity? What is the initial? What is the total time?

6. Calculating Acceleration
A skateboarder is moving in a straight line at a speed of 3 m/s and comes to a stop in 2 sec. What is his acceleration?
a = 0 m/s m/s
2 s
a=-1.5 m/s/s
Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
What is the final velocity? What is the initial? What is the total time?

7. Calculating Acceleration
Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
a = 16 m/s - 0 m/s 4s
a= 4 m/s/s
Look at the images of the cars. What is the final velocity of the car? What is the initial? What is the total time?
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

8. Calculating Acceleration
A skydiver accelerates from 20 m/s to 40 m/s in 2 seconds. What is the skydiver’s average acceleration?
Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
a = 40 m/s m/s 2s
a= 10 m/s/s
What is the final velocity? What is the initial? What is the total time?

9. Calculating Acceleration
An airplane accelerates off the ground from 50 m/s and reaches cruising at 100 m/s. What is the airplane’s average acceleration?
Acceleration (a) = final velocity (vf) – initial velocity (vi)
time (sec)
Average acceleration can’t be determined! You don’t know the time in which is changed velocity

10. Think Aloud
Is it acceleration if a bird changes direction while in flight?
What type of acceleration does the second hand on a clock demonstrate?
If a car gains speed as it backs up, is this negative acceleration?
1. No. It is positive acceleration because it is speeding up.
2. Yes. A change in direction is acceleration.
3. A second hand is an example of centripetal acceleration

11. OUT
Alex is observing a car race. As the car turnsa corner, it is traveling at 80km/hr. As the car crosses the finish line, it is traveling at 140km/hr. Which term describes these measures?
Speed
Velocity
Average speed
Average velocity