Dimensional Analysis
A scary sounding name for something that
is pretty darn easy.
Why it’s important to include
your UNITS
• Units are essential to understanding
data.
• A unit gives definition to a numerical
value.
• 100 = number. 100 what?
– The number alone does not tell us much.
• 100 kg is a quantity.
– The unit gives us more information.
Scientists speak METRIC!
- When scientists measure anything they
use the metric system.
- 3 basic units are:
• Mass = Gram
• Volume = Liter or m3
• Length = Meter
Just add a PREFIX
(Language Arts in Science, Crazy!!)
The basic units can be further defined by
adding a prefix.
The main units we will use are:
• Kilo = 1000
• Centi = 1/100
• Milli = 1/1000
Tools for Measure
• Mass= Scale
• Volume=
• Meter stick
• Ruler
• Graduated cylinder (displacement)
• Length=
• Meter stick
• Ruler
Converting Units
Dimensional Analysis a.k.a. Factor
Labeling
• We use proportions to convert from one
unit to another.
• Some rules to remember:
– Carry your units through the entire
problem. Don’t lose them.
– Use what you know or info that you are
given (pg. 6- “Tools of a Scientist” binder packet).
Example Problem: How many
centimeters in 2 meters?
• We know how many meters. We want
to know how many centimeters that is.
• Known fact: 1 m = 100 cm
• Turn what you know into a ratio
2m
X
100cm
1m
= 200cm
Let’s Practice.
Work with a partner, then check with your table
1.
2.
3.
4.
5.
6.
How many grams in 5 kg?
How many centimeters in 6km?
How many millimeters in 1.5cm?
How many milliliters in 2.3 L?
How many meters in 16.4 km?
How many liters is 460 ml?