Vector and scalar quantities are discussed, as well as velocity vs speed, and displacement vs distance

1. Today’s Objectives
-Learn what vector and scalar quantities are
-Be able to distinguish between vector and scalar quantities
-Learn if some common measurements (speed, weight…) are
vector or scalar quantities
-Learn the differences between speed and velocity
-Learn the difference between displacement and distance

2. What is a Scalar Quantity?
Scalar quantities have only magnitude (=how much)
Examples:
• 10 meters
• 2 liters
• 20 kilometers per hour
• 30 baht

3. What is a Scalar Quantity?
Scalar quantities have only magnitude (=how much)
Examples:
• 10 meters
• 2 liters
• 20 kilometers per hour
• 30 baht
Scalar
10 meters

4. What is a Vector Quantity?
Vector quantities have magnitude AND direction
Examples:
• 10 meters to the northeast (=displacement)
• 100 kilometers and hour to the west (=velocity)

5. What is a Vector Quantity?
Vector quantities have magnitude AND direction
Examples:
• 10 meters to the northeast (=displacement)
• 100 kilometers and hour to the west (=velocity)
Vector
10 meters to the NE

6. Why are Vectors Important?
Can an asteroid’s path be
described using vectors?
Yes! Asteroids have
speed AND a direction
We know when
meteor showers are
coming because of
our understanding of
vectors

7. Practice
Label each quantity scalar or vector
1. 80GB
2. 20 meters per second to the north
3. 20 degrees Celsius
4. 25 centimeters
5. 8 Newton force upward
6. 35 seconds
7. 1.3 billion people in China
8. 80 kilograms

8. Answers
Label each quantity scalar or vector
1. 80GB no direction = scalar
2. 20 meters per second to the north has a magnitude and
direction = vector
3. 20 degrees Celsius no direction = scalar
4. 25 centimeters no direction = scalar
5. 8 Newton force upward magnitude and direction = vector
6. 35 seconds no direction = scalar
7. 1.3 billion people in China no direction = scalar
8. 80 kilograms no direction = scalar

9. Displacement vs Distance
Distance – how far something moved (meters)
Displacement – how far, AND what direction something moved
(meters to the NW)
Displacement Distance
VECTOR 18 km
18 m to the NW SCALAR

10. Displacement vs Distance
Distance – how far something moved (meters)
Displacement – how far, AND what direction something moved
(meters to the NW)
Is the red or yellow line distance?
DISTANCE Red is distance = how far moved
Finish
Yellow is displacement = how far
and what direction
DISPLACEMENT Displacement is always a straight
line, and will always be shorter
than distance
Start

11. Displacement vs Distance
Distance – how far something moved (meters)
Displacement – how far, AND what direction something moved
(meters to the NW)
Classwork:
1. A man walks around the outside of park and ends up in the same spot he started.
What is his displacement? How much distance did he travel?
1km
*His displacement is 0
*His distance traveled is 4 km 1km PARK 1km
Start
*Scalar or vector? 1km
Finish

12. Speed
Speed is how fast an object is traveling
Speed = distance (in meters)
time (in seconds)
s=d
t
It takes a swimmer 57.2 seconds to swim a distance of 100 m.
What is the swimmer’s average speed?

13. Speed
Speed is how fast an object is traveling
Speed = distance (in meters)
time (in seconds)
s=d
t
It takes a swimmer 57.2 seconds to swim a distance of 100 m.
What is the swimmer’s average speed?
s = d = 100m = 1.75 m/s
t 57.2s

14. Speed
Speed is how fast an object is traveling
Speed = distance (in meters)
time (in seconds)
s=d
t
It takes a swimmer 57.2 seconds to swim a distance of 100 m.
What is the swimmer’s average speed?
s = d = 100m = 1.75 m/s
t 57.2s Scalar or vector??

15. Speed
Speed is how fast an object is traveling
Speed = distance (in meters)
time (in seconds)
s=d
t
It takes a swimmer 57.2 seconds to swim a distance of 100 m.
What is the swimmer’s average speed?
No direction
s = d = 100m = 1.75 m/s
t 57.2s Scalar or vector?? Scalar

16. Velocity
Velocity is how fast an object is going, AND its direction
Velocity = displacement (in meters)
time (in seconds)
Remember, displacement is distance AND direction
If you need to go from point A to point B in 10 minutes, what
velocity do you need to get there on time?
3.7 km N
A B
W E
Velocity = 3.7 km east = 0.37 km east/ minute
10 minutes S
Scalar or vector? Vector because has direction

17. Speed vs Velocity
Speed – how fast something is moving (m/s)
Velocity – direction and speed of an object (displacement/s)

18. Speed vs Velocity
Speed – how fast something is moving (m/s)
Velocity – direction and speed of an object (displacement/s)
If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that a
vector or scalar measurement??

19. Speed vs Velocity
Speed – how fast something is moving (m/s)
Velocity – direction and speed of an object (displacement/s)
If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that a
vector or scalar measurement?? Speed has no direction = Scalar

20. Speed vs Velocity
Speed – how fast something is moving (m/s)
Velocity – direction and speed of an object (displacement/s)
If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that a
vector or scalar measurement?? Speed has no direction = Scalar
If I say “I’m driving 85 kilometers and hour north toward Chiang
Mai”, is that a vector or scalar measurement??

21. Speed vs Velocity
Speed – how fast something is moving (m/s)
Velocity – direction and speed of an object (displacement/s)
If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that a
vector or scalar measurement?? Speed has no direction = Scalar
If I say “I’m driving 85 kilometers and hour north toward Chiang
Mai”, is that a vector or scalar measurement?? Velocity has speed
and direction = Vector

22. Some Common Measurements
Measurement Example Vector or Scalar
Speed 20 meters/second no direction = scalar
Length 12m no direction = scalar
Displacement 10m to the north direction = vector
Volume 3 Liters no direction = scalar
Area 23 meters squared no direction = scalar
Mass 29 grams no direction = scalar
Velocity 60km/h to the north direction = vector
Force 56 Newtons down direction = vector

23. Decide Scalar or Vector
Energy Scalar Vector
Length
Area
Volume
Speed
Displacement
Time
Velocity Temperature
Mass
Force

24. Remember…
Scalar quantity has no direction
Vector quantity has direction
Displacement is distance with direction
Velocity is speed with direction
Don’t let these words scare you, they sound
complicated, but they really aren’t.

25. Complete Questions in Notebook
Directions: Write vector or scalar
15-21 Complete the table
1. 40 baht ______________
2. 20 Joules ______________ Measurement Scalar or Vector
3. 1.2 billion atoms ______________
4. 28 degrees Celsius ______________ 15. Mass
5. 8 km/hr west ______________
6. 25 N down ______________ 16. Displacement
7. 3 Liters ______________
17. Area
8. 23 km/hr in Bangkok______________
9. 10 m west ______________ 18. Velocity
10. 79 kg ______________
19. Force
Directions: fill in
11. Velocity is speed with __________. 20. Speed
12. Displacement is direction and __________.
21. Weight
A mountain bike rider followed the red line
13. What was his displacement? 53km
14. What was his distance traveled? Write questions and
Finish
answers in notebook
27km NE
Start