1. Math Review - 2

2. Part II. Dimensional Analysis
Dimensional Analysis (also called Factor-Label Method or the Unit Factor Method)
is a problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value.
Uses equalities written as conversion factors

3. Sample Problem: How many days are in 2.50 years?
1) Write down what you are given.
2) The unit to cancel goes on the bottom.
The unit to convert to goes on the top.
3) Check unit cancelation.
2.50 years
365
days
= days 1
year
4) Do the MATH.

4. Conversion Factor
A conversion factor takes an equality and converts it into a ratio.
For each unit equation, you can write two conversion factors!
For the equality 1 hour = 60 minutes,

5. Sample Problem: How many days are in 2.50 years?
1) Write down what you are given.
2) The unit to cancel goes on the bottom.
The unit to convert to goes on the top.
3) Check unit cancelation.
2.50 years
365
days
= days 1
year
4) Do the MATH.

6. Sample Problems: 1) Change 5 years to minutes = 109 500 min
2) Change 2.4 miles to inches
= in
3) Change 25 km/h to m/s
= 6.94 m/s

8. PART III. SCIENTIFIC NOTATION
We use Scientific Notation to represent very large and very small numbers using powers of 10.
A x 10n
Determine A by shifting the decimal point to the left or right until only one is to the left of it. (1 ≤ A < 10)
Determine n by the number of places the decimal has been moved;
if moved to the right n is positive,
if moved to the left n is negative

9. Examples: Earth’s mass = 5 980 000 000 000 000 000 000 000. kg
Move 24 places to the left
= 5.98 x 1024 kg
Radius of proton = m
Move 15 places to the right
= 1.2 x m
You try some…

10. How do I use my calculator?
Let’s key in these problems:
A) 1.2 x 103 =
1 200
B) 2.5 x 10-4 =
C) 1.2 x 103 x 2.5 x 104 =
3.0 x 107
In Multiplication the exponents add
D) 3.6 x 109 / 6.0 x 105 =
6.0 x 103
In Division the exponents subtract