Welcome to Physics!!Day One Agenda:

Who are we?

Formalities

Syllabus: Online!

Books, Reference Tables

Tissues = Gold

What is Physics?

Unit 1 !!!

Scientific Calculators

► Texas Instruments = Good► Casio = Garbage

Mediocre

Best!!

TI-30XIIS

Target Practice

Quiz!

► Doesn’t Count (except if not complete)► Try ALL Questions► Used as a status indicator

Topic Pre-I: Measurement and Mathematics

What do we use to measure Physics?

How are accuracy and precision different?

What is scientific notation?

How can quantities be represented on graphs?

Essential Questions

I. Units

A. “Comparison to a known standard”

B. MOST numbers have a unit and they MUST be written (usually a symbol)

C. The SI System 1. Used everywhere

2. Fundamental Units: Simplest• Examples: Meters (m) Seconds (s)

3. Derived Units: put two or more fundamental units together

• Example:

Force =

= Newtons (N)

kilogram • metersecond2kg • m

s2

F =

4. Fundamental Prefixes: PRT’s Front Cover!

D. Addition and Subtraction require all quantities to have the same units• Example:

200km + 34000m = ?

Should Be:

200 km + 34 km = ?

or:

200,000 m + 34,000 m = ?

II. Measurements, Units, & Instruments

Length

Mass

Time

Force

Name of Instrument

Ruler

Triple Beam BalanceStopwatch/Clock

Spring Scale

(m)

(kg)

(s)

(N)

Name of Instrument

Volume

Temperature

Graduated Cylinder

Thermometer

(L)

(K)

(°C)

Name of Instrument

Angles

Electricity

Protractor

Voltmeter

Ammeter

(°)

(V)or (A)

Journal #1 8/28/13

► What is 6.37 x 105 m in standard form?► What is 0.0000000000667 in scientific

notation?► How many megameters are in 5,500,000 m?► How many kilometers are in 5,500,000 m?► Which of these is NOT a fundamental unit?

meters, Newtons, meters per second, kilograms

III.

AKA: Sig Figs

PRESERVE ACCURACY!!

A. The Rules

1. All NON-Zero digits are significant

2. Zeros before a nonzero are NOT significant

• 0.005 cm

ONE significant digit

• 0.75 cm TWO significant digits

3. Zeros between two nonzero digits ARE significant

• 25,001 Ω

FIVE significant digits

• 0.203 kg THREE significant digits

4. Zeros to the right of a nonzero digit ARE significant if followed by a decimal or

are to the right of a decimal

• 30 sec

• 40. sec

• 10.0 sec

• 3.600 sec

ONE

TWO

THREE

FOUR

5. Correct number of Significant Digits is always shown automatically when

scientific notation is used

• Example: 2.45 x 108 has 3 sig figs

6. Operations using sig figs• One Rule: Final answers have the same

number of significant digits as the LEAST sensitive measurement (lowest number of sig digs)

Add:420 cm 0.515 m 0.80 m

• Example

B. Estimating Orders of Magnitude1. Always think in powers of 10

103 = 1000 101 = 10 100 = 1 10-2 = 0.01 etc.

2. Examples:• a pencil is closest to _____ kilograms• the distance from Arlington to Carrollton is closest to _____ kilometers

Journal #2 8/29/13

► What is 4.98 x 109 m in standard form?► How many gigameters is the above

distance?► How many megameters is the above

distance?► How many kilometers is the above distance?► How many significant figures are in each of

the numbers below? 100,000,005 m 8.621 x 103 V 30.0000 s 200 s

► Add: 2.3 km, 3500 m, and 4.625 km

With proper sig figs!!

IV. Precision vs. Accuracy

A. Precise = measurements with great detail

(More decimal places)

B. Accurate = Acceptable, consistent measurements

(close to the scientifically proven values)

A. Vectors are arrows that represent actual measurements to scale• Example: Let 1 meter = 1 centimeter

Therefore: 50 m would be a 50 cm arrow

V.

• The number of a vector is its magnitude

B. Vectors have both magnitude and direction• Examples:

velocity force

22 m/s East

45 N at 30o

C. Scalars: values that only have magnitudes (a certain number of something)

• Examples: time mass30

Seconds100 Kilograms

D. Vector Combination1. Can involve both addition and subtraction

2. Resultant: A combination of two or more vectors

3. Vectors are always combined tip to tail (start of one to end of other)

+ =Resultant

4. If vectors are acting in different directions, find the difference in magnitudes and combine tip to tail to find the direction resultant points the same direction as the largest vector

+ = ?

=Resultant

5. Vectors at angles to each other are still combined tip to tail!

angles of vectors must be preserved

The resultant connects the beginning of the first vector to the end of the last vector

Most cases only involve two vectors

sometimes there can be multiple vectors involved, but the process stays the same!

Resultant

Resultant

Graphical vector combination can be done using metric rulers and protractors!

Journal #3 8/30/13

► Find the hypoteneus in the following triangle!

► Then use “trig” to find the angle!

10m

18m

Journal #4 9/3/13

► Find the hypotenuse and adjacent side in the following triangle if the angle θis 22.6°

5m

?

?

θ

E. Breaking Down Vectors1. It is MUCH easier to combine vectors using horizontal and vertical components

2. horizontal component = X component

vertical component = Y component

3. X and Y components can be combined

+ =

+ =

All X components are Horizontal

All Y components are Vertical

4. Diagram of Vector C and Its X – Y Components

Horizontal Component

Vertical Component

• subscripts on the components differentiate them from the original vector C

6. Horizontal and Vertical components make a right triangle so any side can be found

cosθ = A/H

Adjacent = Ax

Hypotenuse = A

Ax = Acosθ

sinθ = O/H

Opposite = Ay

Hypotenuse = A

Ay = Asinθ

7. Example:Ali drags a heavy box with a tensional force that acts up to the right at an angle of 40 degrees. What are the horizontal and vertical components of the force?

1. Used to express very large and very small quantities

2. General Form: A x 10n

• A is a number between 1 and 10

• n is a “power” equal the number of places to move the decimal point

+ for numbers greater than 1

- for numbers less than 1

VI. Scientific Notation

4. Multiplying and Dividing Sci. Notation• Rules:

To multiply, add powers of ten (the n’s) and multiply the other numbers (the A’s)

To divide, subtract the powers of ten (the n’s) and divide the other

numbers (the A’s)

3. Adding and Subtracting Sci. Notation

make the powers of ten (n’s) the same and then just add (the A’s) together

Examples: 100 =

100,000 =

0.001 =

• Addition Example:

2.1 x 105 kg + 8.7 x 104 kg

Final Answer: 2.97 x 105 kg

• Multiplication/Division Examples:

Multiply: (1.5 x 105 km) (2.8 x 103 km)

Divide: (1.5 x 105 km) (2.8 x 103 km)

VII. The Trig of Physics

A. Right Triangles are used VERY OFTEN in Physics

B. Use the Pythagorean Theorem to solve for the length of a missing side

• Formula: 222 bac

C. Angle Trig

SOH CAH TOA

Oscar Had A Heap Of Apples

How on Earth do you remember all that???

It’s in the PRT’s!!!

(page 5)

VIII. Graphs

A. Format

B. Vocabulary• Direct • Interpolate

• Indirect • Extrapolate

• Static • Slope

• Cyclic

• Direct Squared

• Indirect Squared

Frequency (Hz)

En

erg

y o

f a P

hoto

n (

J)

the slope of the graph is which meansthat the slope is proportional to

f

E

h

Elongation (m)

Forc

e o

f a S

pri

ng

(N

)

the slope of the graph is which meansthat the slope is proportional to

x

Fs

k

the slope of the graph is which means

that the slope is proportional to

Force (N)

Acc

ele

rati

on

(m

/s2)

F

a

m

1

Current (A)

Pote

nti

al D

iffere

nce

(V

)

► Look up the symbols on the PRT’s for the variables shown on the graph below… then show the slope of the graph using the slope formula.

► Explain the significance of the slope of the graph

► State the relationship shown on the graph along with the type of relationship.

Journal #X 9/10/13