Transcript 01 Conversions - Crestwood Local Schools

MEASUREMENT
Part 2
Unit Conversions
Number vs. Quantity
• Quantity - number + unit
UNITS MATTER!!
The Metric System
• Easier to use because it is based on powers of 10.
• A metric unit has two parts:
A prefix and a base unit
• Example cm, mL, mg
• The prefix tells you how many times to divide or multiply
by 10
Some Base Units
• Length - meter(m) - more than a yard
• Mass - grams(g) - about a raisin
• Volume - Liter(L) - half of a two liter bottle
Some Prefixes
•
•
•
•
•
•
•
•
kilo
Hecto
Deka
deci
centi
milli
Micro
Nano
k
h
dk
d
c
m
µ
n
1000 times
100 times
10 times
1/10
1/100
1/1000
1/1000000
1/1000000000
SI Units
Prefix
mega-
Symbol
M
Factor
106
kilo-
k
103
BASE UNIT
---
100
deci-
d
10-1
centi-
c
10-2
milli-
m
10-3
micro-

10-6
nano-
n
10-9
pico-
p
10-12
Intro to Dimensional Analysis
• How long can you hold your breath?
• Convert it to DAYS!
Dimensional Analysis
• The “Factor-Label” Method
– Units, or “labels” are
canceled, or “factored” out
g
cm 

g
3
cm
3
Dimensional Analysis
• Steps:
1. Identify starting & ending
units.
2. Line up conversion factors
so units cancel.
3. Multiply all top numbers &
divide by each bottom
number.
4. Check units & answer.
Conversion Factors
• Conversion factor- a fraction based on a
definition and equal to 1
– Example:
• 1 cm = 0.01 m
• Conversion factors possible:
1 cm
0.01 m
0.01 m
OR
1 cm
Dimensional Analysis
Your European hairdresser wants to cut
your hair 8.0 cm shorter. How many
inches will he be cutting off?
cm
in
8.0 cm
1 in
2.54 cm
= 3.2 in
Factor-Label
Convert 1000 grams to pounds
When 1 pound is equal to 454 g. g  lbs
1000 g
1 pound
= 2.2 pounds
454 g
Dimensional Analysis
Taft football needs 550 cm for a 1st down.
How many feet is this?
cm
550 cm
ft
1 in
1 ft
2.54 cm
12 in
= 18 ft
Dimensional Analysis
• If there are 5280 ft in 1 mile, and you run
8.5 miles, how many cm did you run?
1 in = 2.54 cm
Questions?
• “The ultimate measure of a person is not
where they stand in moments of comfort
and convenience, but where the stand in
times of challenge and controversy.”