WARM UP 8-26-13

AgendaQuiz Unit 1Notes Unit 1-4WS Unit 1 DensityWork on online HW

HomeworkAug 28 – Online HW unit 1Aug 31 - Test review WSSept 2 – Test unit 1

1. Find the density of this solid, mass = 180 grams

2. Find the mass of an object if it takes up 4 cm3 and has a density of 5 g/cm3

3. Find the volume if an object weights 70 grams and has a density of 14 g/cm3

Unit 1-4Rounding Measurements

Accuracy- how close a measurement is to the actual value

Rounding Measurements Precision- how frequently you get the same

measurement when measuring in the same way

Rounding Measurements Round the following numbers: 5.76 to the nearest tenths 453 to the nearest tens 3.685 to the nearest hundredths

Scientific Notation Used to make numbers easier to deal with

and to keep track of zeros

Only one number before decimal!

Using calculators with scientific notation: Number * 10 ^ (exponent) Number EE (exponent)

Scientific Notation Examples

Assignments Unit 1 density WS due today before leaving

class

Online HW Unit 1

Test review WS

EXTRA NOTES NOT APPLICABLE

Significant Figures Significant figures are used to indicate the

preciseness of measurements

- Significant figures consist of all the digits known with certainty as well as one estimated, or uncertain digit

- Use for rounding answers

Rules for Determining Significant Figures

1. Nonzero digits are always significant

e.g. 643.5 has 4 sig figs

2. Zeros between nonzero digits are significant

e.g. 909 has 3 sig figs

3. Zeros in front of non zero digits are not significant

e.g. 0.00034 has 2 sig figs

e.g. 00063

Rules for Determining Significant Figures

4. Zeros both at the end of a number and to the right of a decimal point are significant

e.g. 9.00 has 3 sig figs

5. Assume zero to the right of a number but to the left of the decimal point is not significant

e.g. 4000 has 1 sig fig, but 30.0 has 3 sig figs

Sig Fig Practice

Determine the number of sig figs in each value

a)4658.2

b)4006

c)0.000265

d)0065

e)1.0065

f)3.0

g)700

Sig Figs in Calculations When multiplying and dividing, round your

answer to the least number of sig figs in the equation

Multiplying and Dividing

a)12 x 4 = ?

b)1.0 x 623 = ?

When adding and subtracting, round youranswer to the least number of decimal placesin any of the data you are given.

Adding and Subtracting

a)3.11 + 1.2 = ?

b)9.899 – 2.23 = ?

Sig Figs in Calculations