#### Transcript Measurement

Measurement
Measurement
• Measurements have 2 parts:
– A number
– A unit
• Example: 5cm
• Scientists (and we will) use the SI system
– Système International d’unités
The SI units = METRIC
• There are only 3 countries in the whole world
using the ENGLISH SYSTEM of measurement
– Liberia
– Myanmar (formerly Burma)
– THE UNITED STATES of AMERICA
• Why is the metric system so much easier?
– Most countries use it
– It is based on powers of 10
Units
• There is always a BASE unit for every
measurement
• There can be prefixes added to the base to
make it larger or smaller
Example: millisecond, kilogram
Base Units
•
•
•
•
Length = meter (m)
Mass = gram (g)
Volume = liter (L) or cubic centimeters (cm3)
Time = second (s)
** Prefixes multiply the BASE unit by a value of
10 **
PREFIX
Kilo
hecto
deka
base:
deci
centi
milli
Symbol
k
h
da
d
c
m
multiplier
1,000
100
10
1
0.1
0.01
0.001
King
Henry
Died
Unfortunately
Drinking
Chocolate
Milk
Unit Conversions
• The metric system is so useful because we can convert
from one unit to another EASILY
1. Write out the abbreviations in a horizontal row:
KHDUDCM
2. Find the location of the original unit, then count the
number of jumps and direction to the new unit
3. Re-write the number, then hold the pencil on the
decimal point.
4. Move your pencil, making “egg crates”, the number of
jumps in the correct direction- then fill in the empy
crates with ZEROS
Let’s try some!
Convert:
12 gram to kilograms
87.25 hL to cL
5.22 seconds to milliseconds
99.99 dm to cm
How many centiliters are in 1 kiloliter?
Length
• Length = distance from one point to another
• Length is measured with a METRIC RULER
• The BASE unit = meter
• Examples: centimeter (cm), millimeter (mm),
decimeter (dm)
Mass
• Mass= the amount of matter in an object
• Mass is measured with a balance
• The BASE unit = gram
• Examples: kilogram (kg), milligram (mg)
Volume
Volume= the amount of space something takes up
Solid Measurement
• The BASE unit = cm3
• Use a formula to calculate
for regular shapes
• For irregular shapes use
Water Displacement
Method
Liquid Measurement
• The BASE unit = Liter
CYLINDER to measure
Volume
Direct Measurement
• Use a ruler to measure and
plug into formula
• Example:
Volume of a cube =
length x width x height
Indirect Measurement
• Water displacement
method
with water- record volume
2. Carefully add objectrecord new volume of
water
3. Subtract old volume from
new volume = volume of
object
In order for a measurement to be
reliable…
It needs to be both ACCURATE and PRECISE
• Accuracy = EXACT
• Precision = multiple measurements close to
each other
Scientific Notation
• Makes using large numbers easier
• Write a number times a power of 10
•
•
•
•
•
Example:
3.0 x 108 = 300,000,000
Number must be between 1 and 10
Always there
The NUMBER of places and DIRECTION the
decimal is moved
Scientific Notation
• #’s less than 1 (0.30400823) have a
NEGATIVE exponent
• #’s greater than 1 have a POSITIVE
exponent
Try Some:
• Expand:
• 4.2 x 104
• 3.359 x 10 -6
• 7.8112 x 108
Try Some More…
• Write in scientific notation:
•
•
•
•
870
0.0000789
0.245
75000