Physics 1 Introduction

This Class Pre-Reqs:

Concurrently in Algebra II I recommend that you are in Honors Algebra II or Trig.

Topics: Kinematics Dynamics Universal Law of Gravitation SHM Momentum Energy Rotation Electrostatics Circuits Mechanical Waves and Sound

We will be using basic trigonometry to analyze certain systems. This is why I recommend a higher math class.

Grades

Grade Breakdown: Homework/Classwork: 15% Projects: 15% Quizzes: 15% Labs/Hands-on Activities: 25% Tests: 30%

The semester grade:

80% of class grade + 20% semester final grade

What to Expect:

Homework/Assignments: 2-4 homework assignments/week

(mostly via WebAssign) Problem of the Week Classroom assignments

Labs: 25% of class-time Formal/informal labs Big part of grade

Projects: To be determined 2 per semester (written/hands-on)

Quizzes: Multiple Choice/Free-Response

Tests: AP format Multiple choice/free-response

More on Labs

Formal Lab: Data collection, analysis, full write-up, and extension.

Informal Lab: Data collection, analysis, extension questions but no write-up.

“Hands-On” Activity Really just an informal lab I will pose a question/problem, give you access to certain materials, you will

solve problem physically, and then write a paragraph length response to the question/problem.

I expect you to keep a separate notebook for all labs. This will not be graded but is expected. Most science college courses will require this so get used to it.

The AP Test

Multiple Choice 50 questions, 90 mins, 50% of

score Discrete items Items in sets Multi-select items

Free-Response 5 questions, 90 mins, 50% of

score Experimental Design Quantitative/Qualitative

Translation Short Answer (3 questions,

one requiring a paragraph-length response)

Most of the math will be in the multiple choice section, AP wants you to prove that you actually understand the underlying concepts in free-response.

Expectations:

Respect The speaker (teacher, student, visitor, substitute… etc.) The equipment The classroom Each other

Electronic devices If you are on social sites, games, anything not related to what we are doing I

CAN and WILL take it (I’m very sneaky… very very sneaky) You CAN use it as: timer, calculator, to access WebAssign (IF THAT’s WHAT

WE’RE DOING), to look up conversions, etc.

Expectations

Be Responsible Take notes Do your homework Study Come in for extra help DO NOT wait for the last minute!

Six Flags Magic Mountain

Six Flags Magic Mountain is tentatively scheduled for February and more details will come as the semester goes along

Let’s Get Started

S.I. SYSTEM AND UNIT CONVERSION, SIG-FIGS, UNCERTAINTY, AND LABS

S.I. System

In physics we use the S.I. system of measurement In order for calculations to be correct all measurements must

be converted to their S.I. form. In physics 1, measurements are often given in other systems

MKS: Meters (m) Kilograms (kg) Seconds (s)

Most other units are derived from these (ex: = )

Significant Figures (The Rules)

ALL non-zero numbers are significant (1, 2, 3,…) Ex: 48,562 has 5 significant figures

ALL zeroes between non-zero numbers are significant Ex: 402 has 3 significant figures

ALL zeroes which are to the right AND at the end of a number are significant. 2.00000 has 6 significant figures 0.0004 has 1 significant figure

ALL zeroes which are to the left of a decimal point are ALWAYS significant (because of the decimal point). 10.0 has 3 significant figures 10 has 1 significant figure

AP now requires answers on the AP test to include significant figures. Go figure…

Significant Figures (Tips)

Convert large or small numbers into scientific notation first: 1000.00 = 1.00000 x 103 (6 significant figures) 1000 = 1 x 103 (1 significant figure) 0.00004 = 4 x 10-5 (1 significant figure) 0.0000400 = 4.00 x 10-5 (3 significant figures)

This way you can get rid of the insignificant zeroes!

Addition/Subtraction w/ Sig Figs

Count the number of decimal places in the decimal portion of each number in the problem.

Add or subtract like normal Round the answer to the LEAST number of places in

the decimal portion of any number in the problem Example: 23.112233 (6 decimal places) + 1.3324

(4 decimal places) - 0.25 (2 decimal places) Calculator answer: 24.194633 The least number of significant decimal places was 2 The correctly rounded answer is: 24.19

Practice

1.3.461728 + 14.91 + 0.980001 + 5.26312.23.1 + 4.77 + 125.39 + 3.5813.22.101 - 0.93074.0.04216 - 0.00041345.564,321 - 264,321

1.24.612.156.83.21.1704.0.041755.300,000

Multiplication/Division w/ Sig Figs

The least number of significant figures in any number determines the number of significant figures in the answer.

Must recognize all significant figures (not just the digits after the decimal point) Example: 2.5 (2 sig-figs) x 3.42 (3 sig-figs) Calculator answer: 8.55 The least number of sig-figs was 2 Correctly rounded answer: 8.6

Practice

1. . Watch your order of operations on this problem.

1. 6.17 x 1010

2. 1.340 x 101 = 13.40

3. 4.62 x 10-22

4. 2280

Lab Write-Ups EVERYTHING YOU NEED TO KNOW

Warm-Up

In today’s notes complete the following problems:1. Convert 35.0 mi/gal into km/L with the correct sig

figs. 2. Solve with the correct sig figs:

1 km = 0.6214 mi1 gal = 3.7854 L

Purpose (2 pts.)

Restate the purpose of the lab Identify materials needed for the lab ALWAYS stated in y vs. x form Example:

To determine the relationship between position and time for a battery operated car moving at constant velocity.

Data (2 pts.) Collecting

6-8 values, 3 trials per value Use full range of possibilities

Table Convert to S.I. Units Include Units Only need averaged values

Graph Graph average values only and throw major outliers out (this

must be explained in the error analysis) Any modified data

Graph (5 pts.)

MUST have the following components: Origin set at (0,0) and labeled as such Axes labeled (variable & units) Regression statistics (the box with numbers) “Straight” Line Show the table of graphed data

Graph Example

Graphical Analysis (6 pts.)

y = mx + b (1 pt.) Substitute variables and numbers

with units (found in box) (2 pts.) % error test (1 pt.)

% error <5% throw out “b” 6% < % error < 10% keep “b” % error > 10% see about modifying

Final equation (units of slope must be simplified) (2 pts.) Example: m/s/s = m/s2

y = mx + b position = (2 m/s)time + 0

meters % error = |b/y-max|*100

% error = |0 m/16 m| *100 = 0%

x = (2 m/s)t

Good Morning/Afternoon!

Turn in parent interest survey Have your example labs and lab packets from Friday

out and ready to go.

Conclusion (5 pts.)

Answer the purpose of the lab The relationship between position and time for a battery

operated car moving at constant velocity is ___________. Error Discussion

If error <5% discuss why sources of error were low. If error >5% discuss why where the sources of error came

from

Types of Error

NO SUCH THING AS “HUMAN ERROR”. Do not state this as a source of error in your labs.

Random Errors: an error which affects a measurement reading at random The observer being less than perfect The readability of the equipment External effects on the observed item

Systematic Errors: an error which occurs at each reading The observer being less than perfect in the same way each time An instrument with a zero offset error An instrument that is improperly calibrated

Random errors can be reduced by repeated readings.

Systematic errors can only be reduced by taking better readings.

Precision vs. Accuracy

Precision A measurement is precise if it has little random errors. This means each measurement is close to the others. A measurement can be very precise but not accurate.

Accuracy A measurement is accurate if it has little systematic errors. The measurements are very close to the true value.

Extension Questions (5 pts.)

Physical Significance (2 pts) – what does the slope tell you? Example: The slope represents the velocity of the battery operated car.

Answer extension questions in complete sentences and include evidence. % difference

Sometimes we will compare experimental data with known values This will require a % difference analysis

Example: You determine from a lab that the acceleration due to gravity is 9.68 m/s2. The theoretical value is 9.81 m/s2.

Modifying Data

We always always always graph a straight line. We can modify data by graphing:

y2 vs. x y vs. x2

Y vs. x-1

It depends on what our original graph looks like. The relationship we determine does not change. Still follow the same steps of analysis.