Acceleration- Change in Velocity
•occurs when an object
______________ in speed.
• occurs when an
object __________
in speed.
• occurs when an object _____________________
Types of acceleration
• Increasing speed
– Example: Car speeds up at green light
• Decreasing speed
– Example: Car slows down at stop light
• Changing Direction
– Example: Car turns
screeeeech
Question 1
• How can a car be accelerating
if its speed is a constant 65
km/h?
_______________________________________
_______________________________________
Calculating Acceleration
Acceleration = Final speed – Initial speed
Time
Calculating Acceleration
Acceleration = 16m/s - 0m/s
4s
Acceleration = _______
0s
0 m/s
1s
4 m/s
2s
8 m/s
3s
12 m/s
4s
16 m/s
Question 2
• A skydiver accelerates from 20 m/s to
40 m/s in 2 seconds. What is the
skydiver’s average acceleration?
a=
a=
m/s – m/s
s
____
a = __________
Graphing Acceleration
• Can use 2 kinds of graphs
–Speed vs. time
–Distance vs. time
Graphing Acceleration:
Speed vs. Time Graphs
14
Speed (m/s)
12
10
8
6
4
2
0
0
1
2
3
4
5
6
Time (s)
Speed is increasing with time = accelerating
Line is straight = acceleration is constant
Graphing Acceleration:
Speed vs. Time Graphs
14
Speed (m/s)
12
10
8
Rise = 4 m/s
6
4
Run = 2 s
2
0
0
1
2
3
4
5
6
Time (s)
In Speed vs. Time graphs:
Acceleration = Rise/Run
= 4 m/s ÷ 2 s = ________
Graphing Acceleration:
Distance vs. Time Graphs
35
Distance (m)
30
25
20
15
10
5
0
0
1
2
3
4
5
Time (s)
Curved line means the object is accelerating.
Your speed is increasing. Remember slope = speed.
Question 3
14
Speed (m/s)
12
10
8
Run = 3 s
6
4
Rise = -6 m/s
2
0
0
1
2
3
4
5
6
Time (s)
1)How is the speed of the car changing?
(speeding up, slowing down, or staying the same)
__________________________
2) What is this car’s acceleration?
__________
Question 4
35
Distance (m)
30
25
20
15
10
5
0
0
1
2
3
4
5
Time (s)
1)Which line(s) represents an object that is accelerating?
________________________________
2)Which line(s) show positive acceleration?
________________________________
3) Which line(s) show negative acceleration?
________________________________
4) Which line(s) show constant acceleration?
_________________________________