1. Class Notes August
HW: I often write common mistakes and advise here.
Any trouble with WebAssign?
#4 = units!, #6 = fun?
Today:
Units, prefixes, etc.
Comments about doing HW
Mechanics / Kinematics

2. Which is correct, considering sig figs? (74.50  2.2)/3.885 = ?
42.188
42.19
42.2 42 40
Some other number
Answer d is correct. Keep the least number of significant figures. Here, that’s 2 in the 2.2 number.

3. Which is correct, considering sig figs? 27.1539 + 138.2 – 11.74 = ?
153.6
153.61
Some other number
Answer b is correct. Keep the least precise decimal place. Here, that’s 0.2 in the number.

4. Chapter 1 Estimating an answer Dimensional Analysis Approximation
Can use to check your answers
E.g. Could you carry $10M in gold?
Dimensional Analysis
Make sure the units are correct
If the units are not correct the answer can not possibly be correct!
1 once is $1000, 1 ounce is about 30 g. Roughly 300 kg or 600 pounds.

5. Système International (SI)
Units are standards in terms of which measurements are stated.
Seven units we must define. All else in terms of these.
Interestingly, only 3 countries have not officially adopted the SI system: Liberia, Myanmar, and the USA! (possibly out-of-date. Hard to find out about the first two.)

6. Description SI symbol Length Meter m Mass Kilogram kg Time Second s
Elec. Current
Ampere A
Temperature
Kelvin K
Amount
Mole
mol
Luminous Intensity
Candela cd s
sec
Note: The Ampere not the Amp. Use s for seconds not sec.

7. Système International (SI)
Units are standards in terms of which measurements are stated.
Seven units we must define. All else in terms of these.
Conversions
(multiply by 1!)
Le SI d’Unites. Do conversion of units before prefix.
For convenience, there can
be prefixes assigned.
You need to know these…

8. 109 giga G 106 Mega M 103 kilo k 10-3 milli m 10-6 micro 10-9 nano n
Power Prefix symbol
109
giga G
106
Mega M
103
kilo k
10-3
milli m
10-6
micro
10-9
nano n
m (mu)

9. Have you ever had a physics course before?
I have had a physical science course. Does that count?
Man I took physics already and I’m going to rock your class!
I have not had either physics or physical sci.
d) I thought this was psychology?

10. Why are you in this class?
It is a GSSM requirement and I really don’t want to take it?
It is a GSSM requirement and I’m looking forward to this class.
Whatever; I’m ambivalent.
Mommy told me to do it.

11. Writes No pictures  unknown Didn’t skip a line b/w problems 
Problems & name
Writes
unknown
No pictures 
Didn’t skip a line b/w
problems 
Write given
values
Write general
equation
Solves equation for
unknown first
Then enters values
(without units  )
Answer highlighted

12. No equations, no diagrams, often no units during the calculations, answers are not boxed-in, etc…

13. Homework Read Chapter 2, sections 1-3 HW#03: Get it on Canvas
 Turn in on paper, either with or without the sheet stapled to the front.