1. Metric and Conversions
Mark Ewoldsen, Ph.D.
La Cañada High School

2. Units and Measurement Physics Mrs. Coyle

3. SI Unit Prefixes - Part I
Name
Symbol
Factor
tera- T
1012
giga- G
109
mega- M
106
kilo- k
103

4. SI Unit Prefixes- Part II
Name
Symbol
Factor
centi- c
10-2
milli- m
10-3
micro- μ
10-6
nano- n
10-9
pico- p
10-12
femto- f
10-15

5. Basic Physics – SI Units
Quantity
Unit
Symbol
Length
meter m
Mass
kilogram kg
Time
second S
Volume
liter L

6. Derived SI Units (examples)
Quantity
Unit
Symbol
Speed
meter per second
m/s
Newton
kg m/ s2 N
Energy
Joule (kg m2/s2) J
Pressure
Pascal (kg/(ms2) Pa

7. SI Unit Prefixes for Length
Name
Symbol
gigameter Gm
109
1000 Mm
megameter Mm
106
1000 km
kilometer km
103
1000 m
centimeter cm
10-2
millimeter mm
10-3
1000 μm
micrometer μm
10-6
1000 nm
nanometer nm
10-9
1000 pm
picometer pm
10-12

8. M x 10n M En Scientific Notation M is the coefficient 1<M<10or
M En
M is the coefficient 1<M<10
10 is the base
n is the exponent or power of 10

9. Other Examples:
5.45E+6 or
5.45 x 10^6

10. Numbers less than 1 will have a negative exponent.
A millionth of a second is:
sec 1x10-6
1.0E ^-6

11. Solving Word Problems Analyze List knowns and unknowns.
Draw a diagram.
Devise a plan.
Write the math equation to be used.
Calculate
If needed, rearrange the equation to solve for the unknown.
Substitute the knowns with units in the equation and express the answer with units.
Evaluate
Is the answer reasonable?

12. Unit Conversions Dr. John Mattox Department of Chemistry and Physics
Fayetteville State University
1200 Murchison Rd.
Fayetteville, NC 28301

13. We start by writing down the
Converting
Inches to centimeters
10.0 in cm =
We start by writing down the
number and the units

14. Converting Inches to centimeters 10.0 in 2.54 cm cm = 1 in
Our conversion factor for this is 1 in = 2.54 cm.
Since we want to convert to cm, it goes on the
top.

15. Converting Inches to centimeters 10.0 in 2.54 cm cm = 1 in
Now we cancel and collect units. The inches cancel
out, leaving us with cm –
the unit we are converting to.

16. Converting Inches to centimeters 10.0 in 2.54 cm 25.4 cm = 1 in The
Since the unit is correct,
all that is left to
do is the arithmetic...
The
Answer

17. Even though we have two different numbers
and two different units, they represent the
exact same length. You can check this by
looking at a ruler – find the 10 in mark and
directly across at the cm side. What number
do you find?

18. A more complex conversion
km to m
hr s
In order to work a NSCI 110 homework
problem, we need to convert kilometers
per hour into meters per second. We
can do both conversions at once using
the same method as in the previous
conversion.

19. A more complex conversion
km to m
hr s
Step 1 –
Write down the
number and the
unit!
80 km hr

20. A more complex conversion
km to m
hr s
80 km
1 hr m = s hr
3600 s
First we’ll convert time. Our conversion factor is
1 hour = 3600 sec. Since we want hours to cancel
out, we put it on the top.

21. A more complex conversion
km to m
hr s
80 km
1 hr
1000 m m = s hr
3600 s
1 km
Next we convert our distance from kilometers to
meters. The conversion factor is 1 km = 1000 m.
Since we want to get rid of km, this time it goes
on the bottom.

22. A more complex conversion
km to m
hr s
80 km
1 hr
1000 m m = s hr
3600 s
1 km
Now comes the important step – cancel and collect units.
If you have chosen the correct conversion factors, you
should only be left with the units you want to convert to.

23. A more complex conversion
km to m
hr s
80 km
1 hr
1000 m = hr
3600 s
1 km
80,000 m
Since the unit is correct, we
can now do the math – simply
multiply all the numbers on the
top and bottom, then divide the
two.
3600 s

24. A more complex conversion
km to m
hr s
80 km
1 hr
1000 m = hr
3600 s
1 km
80,000 m m s 22
The
Answer!! =
3600 s

25. both velocities. A car that is exact same velocity as a car
80 km/hr and 22 m/s are
both velocities. A car that is
moving at a velocity of
80 km/hr is traveling the
exact same velocity as a car
traveling at 22 m/s.