Transcript WU 8/29 - ouhsd

WU 8/31
• Create the following data table in your notes.
Measurement
Number of paperclips
Length of pen/pencil
Volume in beaker
Volume in graduated
cylinder
Temperature of water
Value
WU 9/1 **Take Out HW**
1. Read page #1 of the Syllabus
2. What category of this class has the most effect on
your grade?
3. When you walk into the room each day, what is
expected of you?
4. As simply as possible, state the tardy policy for this
class.
5. What is the policy on late work?
6. What is the URL for the class website?
WU 9/2
• Adjust your data table from yesterday.
Measurement
Number of paperclips
Length of pen/pencil
Volume in beaker
Volume in graduated
cylinder
Temperature of water
Value
New Value
# Sig. Figs
In your notes…
• Write what you think the word
significant means.
3-1 Significant Figures
• Measurements have some uncertainty.
• When taking a measurement, significant
figures are :
–all the digits that are known,
–plus one digit of uncertainty, or a guess.
Rules for significant figures:
1. EX: 4.564 has ____ significant figures
– Every nonzero digit in a reported
measurement is assumed to be
significant.
– 5.62 has _____ significant figures.
2. EX: 4.056 has ____ significant figures
• Zeros between nonzero digits are
significant.
• EX: 5.0725 has ___ significant figures.
Rules 3 and 4
3. EX: 0.000435 has _____ sig. figs.
–Leftmost zeros in front of nonzero numbers
are not significant.
–EX: 0.0021
4. EX: 5.0540 has _____ sig. figs.
•Zeros at the end of a number to the
right of a decimal place are significant.
•EX: 9.210500
Rule 5
EX: 50400 has _____ significant figures.
– Zeros at the end of a measurement, to the left of a
decimal place are not significant.
– If a decimal place is included after the zeros, count
the zeros as significant.
– EX: 649000. has _____ significant figures.
Rule 6
EX: There are 34 students in this class
• Given values, or exact quantities have
infinite significant figures
Practice
• How many sig figs are in the
following numbers?
- 3.0345
- 6.230
- 0.0000678
How many significant figures are in the
following measurements?
a.
b.
c.
d.
e.
f.
5.6780 g
0.00381 s
679000.0 m
6.0834 kg
5 apples
3.000 cm
a. 5
b. 3
c. 3
d. 5
e. Infinite
f. 4
Significant Figures & Math
• In General: calculated measurements are only as
good as their weakest link (fewest sig figs)
• Addition & Subtraction
– round answer according to fewest decimal places.
(Don’t count digits to the left of the decimal place)
• Multiplication & Division
– Round answer according to fewest significant figures in
measurements
(Count ALL digits)
• **These rules are on p. R60 as well