Mr. Burkholder

Ch 1 PowerPoint Notes

Scientific notation is a way of expressing a value

as the product of a number between 1 and 10

and a power of 10.

Scientific Notation has 2 parts: 1st is a number from 1 to 9.9. 2nd is x10 to a power. First

must contain only significant figures.Ex: 6.02 x 1023

Starting Number1.0 is ok.

.9 is not ok.10.0 is not ok.

Must be less than 10 and greater than or =

to 1.

Significant FiguresThe starting number

must contain all significant figures and only significant figures.

1.00 x 104 mis different than

1 x 104 m

Which of these is wrong?

1.2 x 104 m

1.4 x 10-7 g

39 x 104 m/s

Significant Figures (SF) are the numbers known precisely plus at least one estimated digit. Using

Sig Figs means that there is uncertainty.

Significant figures are used to show how precise a measurement is. A measurement with 1 SF (2L) is not as very precise.Count number of cups on my desk. Measure length of my pointer as 63 and 64.02 cm and compare. Tell my engineering story about 44.00 ft steel beams.

1. All non zero’s are significant 443 = 3SF 1432 =4SF8.4422 =5SF

How many SF does the number 534 have?

2. Zeros between nonzero digits are SF

20,002 = 5 SF101 =3SF30,421 =5SF10,921 =5SF3004 = ? 030040 = ?

  NOTE Starting Zero are not Significant. (Place holding zeros

are not SF (to the left))

0.0001 = 1 SF 0.00045 = 2 SF5.4 = 2SF

0.000000001 = 1SF0.00345 = ?

 3. Zeros at the end of a number are not significant, unless they

appear after the decimal point or if there is a decimal point.

2000 = 1 SF 2000. = 4 SF2040.010 = 7 SF10 = 1 SF10. = 2 SF

0.00100 = ?SF (look back)

4. Counted numbers have unlimited SF, no uncertainty

23 people = unlimited SF144 eggs=unlimited SF

5. Defined quantities (Conversion factors) have unlimited SF,

no uncertainty

1 dozen = 12 eggs = unlimited SF

Dimensional Analysis = multiplying units together so that they cancel.

Treating units as algebraic quantities, which can be cancelled.

Dimensions = UnitsHow many nickels are equal to $7.20?                                                                                                                                  

Steps for solving problems

Step 1: Analyze the Problem

Put the known on the left. Put the unknown on the right with an

equal sign.

Steps for solving problemsStep 1: List known and unknown.

Step 2: Solve for the UnknownList conversion factors and multiply.

Conversion factor units are often

Unknown units Known Units

Steps for solving problemsStep 1: List known and unknown.

Step 2: Multiply by conversion factors.

Step 3: does the answer make sense?

Conversion factorA conversion factor is a multiplier equal to 1 (top is equal to bottom).

1 in = 2.54cm (you can construct the following 2 conversion factors):

Convert 52.3cm into meters

Step 1: List known and unknown.

Convert 52.3cm into meters

Step 2: Multiply by conversion factors. Unknown units

Known Units

Convert 52.3cm into meters

Put numbers into conversion factors

Convert 52.3cm into meters

Multiply and/or divide

10 meters is how many kilometers?

(What is wrong with this answer?)

Ans: SF

$7.20 X _______Q

$

(for practice, convert to Quarter’s first)

$7.20 X _______Q

X _______N

$ Q

$7.20 X _______Q

X _______N = N

$ Q

$7.20 X _______Q

X _______N = N

$ Q

7.20 x 4 ÷ 1 x 5 ÷ 1 = 144N

144 N3 SF

How many inches are in 2.3 miles?1 mile has 5280ft

How many days are in 1.7 years?

Significant Figures in CalculationsYour final answer can be no more precise

then your least precise measurement

Rounding off – 0.500 round up

0.499 round down

ex - Round to 3 (SF)345678 = 3.46 x 10 5

0.4507 = 4.51 x 10 -1

Multiplication and Division – Round the answer to have the same SF as the least precise number in the problem

(12 only has 2 SF, answer will only have 2 SF)

12m x 4567m x 123m = 6740892 (2 SF)

6.7 x 10 6 m3

How many Sig Figs will each answer have?

25cm x 3.0cm =

50g x 5 =

0.01g ÷ 3.00mL =

Addition and Subtraction –Line up the decimal points. Answer has same Sig Fig as “biggest value” Sig Fig number.

0.45m + 2.11111m + 13.2m 0.45m 2.11111m+ 13.2m 15.76111m correct answer 15.8m

Addition and Subtraction –Example.Someone made $42,512.77 cents.

How much more money does he have?

Answer: 0. Why?

Addition and Subtraction –Example.Someone made $42,512.77 cents.

How much more money does he have?

Answer: 0. Why?

His name is Bill Gates. 4 Billion Dollars plus $42,512.77 is still 4 Billion Dollars.

How many SigFigs does the answer have? Finger Vote. Answer is rounded to $=1, Dimes=2, or

Pennies=3.

$2.13 + $3.15 =

2.33L+ 1.7L =Shout Out

1 x 102m + 9.88m =

SI units

SI units• SI units use prefixes. Memorize them for the test.

Look on the inside of your text book for 1012 to 10-12

Remember that

king henry Died by drinking chocolate milk.

Old: k h D b d c m

New: k h da b d c m

b = base unit

What are the base units in SI?

Official Mass = kilogram (kg)

Mass = amount of matter in an object= kilogram (kg)

We often will use grams for small masses.

New Definition: Mass is the resistance to changes in motion of an

object. Bigger masses take more force to change their motion. Is it

harder to move a tennis ball or a car?

Official Length =

meters (m)

SI units

• Distance is measured in Meters or Kilometers.

Volume =space occupied by an object= (L)

Volume = m3 we will often use liter (L)

LITER IS NOT AN SI UNIT!!!

Density = Mass ÷ Volume

What has more mass 1kg of feathers or 1kg of

rocks?

Mass is not equal to weight!!!

Why?

Time = seconds (s)

Temperature = Kelvin (K)

Density = Mass / Volumevolume - amount of space

taken up by an object.

Mass - quantity of matter in an object

Can the density of an object change?

Do things expand or contract when they get hot?

Mathematics and Physics

A hypothesis can be tested by conducting experiments, taking measurements, and identifying what variables are important and how they are related. Based on the test results, scientists establish models, laws, and theories.

Scientific Methods

Section

1.1

Mathematics and Physics

• 1. Observations and Testable Question: Observe and ask a question.

• 2. Hypothesis: A prediction.

• 3. Experiment: Test hypothesis.

• 4. Analysis and Conclusions: Calculations and confirm hypothesis.

• 5. Theory and Communicate: Discuss the results.

5 paragraphs of the Scientific Method