Transcript Lesson 6

• A measure of…
How far something goes
and…
How long it takes to get there.
The only difference between speed and
velocity is that velocity also specifies
the object is
moving.
Speed can be graphed using
a Position/Time Graph:
Sample graphs:
Graph B shows constant speed. How can
you tell?
Speeding up…
Position
Time
Slowing down looks like this:
Position
Time
No motion
• Stuck at a single
position means no
motion.
Position
Time
Stop!
Don’t
move!
• When something about velocity changes,
we say the object has
• An object accelerates when it speeds up,
slows down, or changes direction.
• We can also GRAPH ACCELERATION!
We have a Mathematical Formula
to figure out acceleration…
Final velocity - Starting velocity
time it takes to change velocity
What units do we measure acceleration in?
-Acceleration is how fast (time) velocity changes
(distance/time).
So…Acceleration is measured in units of
distance/time/time
What are velocity-time graphs?
• 1. These graphs show the
acceleration of objects.
• 2. Time is plotted on the x-axis and
velocity is plotted on the y-axis.
Example 1. Constant Speed.
CONSTANT SPEED
Velocity in km/hr
70
60
50
40
30
20
10
0
2
4
6
Time in Minutes
8
10
Positive Acceleration
Velocity in Miles per Hour
Speeding Up!
160
140
120
100
80
60
40
20
0
Car 1
Car 2
2
4
6
8
10
12
14
Time in minutes
The “steeper” the slope, the greater the positive
acceleration [the faster the car is increasing its
speed]! Which car is speeding up faster?
Deceleration!
Slowing Down!
Velocity in Km/Hr
100
80
60
Car 1
40
Car 2
20
0
2
4
6
8
10
12
14
16
Time in minutes
Negative slope means slowing down or negative
acceleration! Which car is slowing down the
fastest?