Position-Time Graphs

1
Position-Time Graphs

• Vectors Scalars

2
Scalars

• A scalar quantity is a quantity that has
  magnitude only - no direction in space

• Examples of Scalar Quantities
• Length
• Area
• Volume
• Time
• Mass

3
Vectors

• A vector quantity is a quantity that has both
  magnitude and direction in space

• Examples of Vector Quantities
• Displacement
• Velocity
• Acceleration
• Force

4
Distance vs. Displacement
Distance
Displacement
5
Summary of Concepts

• Distance is the length of the path traveled.
• Distance is a scalar quanity
• Displacement (from dis-place to dat-place) is
  the length and direction of a line from start to
  finish.
• Displacement is a vector quantity that contains
  both magnitude and direction.

6
Distance Time Graph
Distance
Time
7
Distance Time Graph
Click the picture below that matches graph A.
Distance
A
Time
8
Distance Time Graph
Click the picture below that matches graph B.
Distance
B
A
Time
9
Distance Time Graph
Click the picture below that matches graph C.
Distance
C
B
A
Time
10
Distance Time Graph
Click the picture below that matches graph D.
D
Distance
C
B
A
Time
11
Distance Time Graph
E
Click the picture below that matches graph E.
D
Distance
C
B
A
Time
12

30
At this speed, how far would you travel
Whats the speed limit?
in 1 hour?
in 2 hours?
in ½ an hour?
in 10 minutes?
30 miles
60 miles
15 miles
5 miles
13

70
50
60
40
If I travel 70 miles in 1 hour, whats my speed?
If I travel 25 miles in ½ an hour, whats my
speed?
If I travel 15 miles in ¼ of an hour, whats my
speed?
If I travel 10 miles in ¼ of an hour, whats my
speed?
14
The unit for Distance is miles The unit for Time
is hours
So what is the unit for speed?
mph
miles per hour
15
The unit for Distance is kilometres The unit for
Time is hours
So what is the unit for speed?
km/h
kilometres per hour
16
The unit for Distance is metres The unit for Time
is seconds
So what is the unit for speed?
m/s
metres per second
The speed of sound is 330 m/s. This is called
Mach 1.
17
Distance Time Graph
Distance (km)
Time (hours)
What speed?
1 hour to travel 20 km
So Speed 20 km/h
18
Distance Time Graph
Distance (miles)
Distance (miles)
?
Time (hours)
What speed?
2 hours to travel 30 miles
So Speed 15 mph
19
Distance Time Graph
Distance (km)
Time (hours)
10 km in 1 hour, so 10km/h.
2¾ hours (2 hours 45 minutes)
¼ of an hour (15 minutes)
What was the speed for the first part of the
journey?
How long did it take to run 40 km?
How long did she stop for?
Approximately 7½ kilometres.
How far in ¾ of an hour?
20

Distance Time Graph
Slower
Distance
Stopped
Fast
Time