mr. baldwinphysics mathematics & measurement9/4/2014 aim: why are rules and procedures...

Mr. Baldwin PHYSICS

Mathematics & Measurement 9/4/2014

Aim: Why are rules and procedures important?

What is Physics?

Do Now: What is Physics? (Write some bulleted points on what

you think Physics is all about.)

Homework: Go to my page on www.whsad.org Download, read, print

and sign class contract, and return it no later than Monday 9-8-14.

Classroom Agenda• Do Now

• Class Instructions

• Group Activity / Worksheets

• Class Reflection

• Bathroom passes will only be issued after classroom instructions are finished

• (No issuance 10 mins. after & before bell).• Derogatory & Offensive Language & tone of voice is

unacceptable.

Homework…

• Due at the beginning of the class on the assigned due date.

• Absolutely No Excuses. Absolutely No LATE homework will be accepted.

• Homework is to be done IN PENCIL on an 8 ½” x 11” white lined filler paper, smooth on all sides, and written on one side only. Your name should be written legibly in the top right corner of your homework and stapled.

• A signed form from a parent/guardian is required to make up any work.

Laboratory…

• All students taking Regents level courses are required to meet the laboratory requirement set forth by the NYS Commissioner of Education.

• Failure to complete the 1200 minutes laboratory assignments results in being barred from taking the Regents Exam.

• Labs will be done in groups. Labs are to be formally written up individually and returned the following week.

• Any plagiarism shall count as a ZERO for both parties involved.

LAB Grading RUBRICRUBRICMISSING (mimi): No written lab submitted

INCOMPLETE (incinc): Lab submitted but key components (< 6.5 pts) (< 6.5 pts) missing.

- missing calculations

- missing graphs

- questions/conclusion unanswered

6.5 – 8 pts6.5 – 8 pts: Lab submitted with at least two (2) components missing

8.5 – 9 pts8.5 – 9 pts: Lab submitted with at least one (1) components missing

10 pts10 pts: Lab submitted and fully completed

MR. BALDWIN’S PHYSICSMR. BALDWIN’S PHYSICS

ASSIGNMENT RUBRICRUBRICMISSING (mimi): NONO Assignment submitted

INCOMPLETE (incinc): Assignment submitted with minimal work done.

-- Homework format not followedHomework format not followed

- - Problem solving format not followedProblem solving format not followed

1 – 31 – 3: Weak attempt made/NONO work shown

4 – 54 – 5: : Fair attempt made/LittleLittle work shown

6 – 86 – 8: Good attempt made/SomeSome work shown

9 – 109 – 10: Work is CompleteComplete & done to specification

MR. BALDWIN’S PHYSICSMR. BALDWIN’S PHYSICS

Responsible for Your Work.Every question is worth

asking.Speak with appropriate

Language.Punctuality is a necessity.Establish a positive

environment.Come prepared to work &

learn.Take turns speaking.

classroom ruleS

Consequences

1. VERBAL WARNING

2. VERBAL WARNING & WRITTEN NOTATION

3. VERBAL WARNING, WRITTEN NOTATION & STUDENT/TEACHER CONFERENCE

4. FAMILY GROUP ADVISOR/PARENTAL NOTIFICATION

5. PARENT/FAMILY GROUP ADVISOR CONFERENCE

6. REFERRAL TO ADMINISTRATION.

What is Physics?Physics is a branch of science that involves the study of the physical world: energy, matter, and how they are related.

Learning physics will help you to understand the physical world.

Physics uses mathematics as a powerful language.

In physics, equations are important tools for modeling observations and for making predictions.

Mr. Baldwin PHYSICS

Mathematics & Measurement 9/5/2014

Aim: What are standard units of measurement?

Do Now: A standard class period is approximately a

microcentury. How long, in minutes, is a microcentury?

Homework: Worksheet 1.2 International System of

Measurement

Mr. Baldwin

PHYSICS

Mathematics & Measurement 9/10/2014

Aim: What are standard units of measurement?

Do Now: Quiz.

Homework: Handout.

7 Basic Units of Measurement

In Physics, we will be working in the SI system, where the basic units are kilograms, meters, and seconds (m.k.s).

Can you think of any other measurements?

• Any other measurements are a combination of the basic units.

15

Subdivisions and Multiples of SI UnitsSubdivisions and Multiples of SI Units

How many cells do you think are in the human body?

• 100 000 000 000 000 000 000 000 000

• Try 1026

• Have you ever heard of an Octillion?

METRIC PREFIXES revised

These are the standard SI prefixes for indicating powers of 10.

CHECK

Can you give any common everyday examples where these prefixes are used?

18

Quiz 1: Prefixes Quiz 1: Prefixes (Let’s have phun)Complete the quantity using the correct metric prefixes. (ex. 1012 – tera, T; 1012 bulls = 1Tbull = 1 terabull)

1.106 phones

2.10-6 phones

3.101 cards

4.109 lows

5.10-1 mates

6.10-12 boos

7.2 x 102 withit

8.2 x 103 mockingbirds

19

AnswersAnswers1. M-phones (megaphones)

2. μ-phones (microphones)

3. Da-cards (deka cards)

4. G-lows (gigalows)

5. d-mates (decimates)

6. p-boos (picoboos)

7. 2 h-withit ( 2 hectowithit)

8. 2 k-mockingbird (2 kilomockingbird)

Mr. Baldwin

PHYSICS

Mathematics & Measurement 9/11/2014

Aim: How do we convert units between the

metric system and British system?

Do Now: Given that 1 m = 3.28084 ft, this 8611-m high mountain is how many feet high? (write your answer in scientific notation)

28250 feet

Did you come up with something like this?

The metric system is easy to use because all the units are based on factors of 10factors of 10.

Let’s see what you came up with?

Why is the metric system easier to

learn than the British system?

RECALL: 7 Basic Units of Measurement

Definitions of Some Standard Units

Quantity Unit Standard

Length Meter Length of the path traveled by light in 1/299,792,458 second.

Time Second Time required for 9,192,631,770 periods of radiation emitted by cesium atoms

Mass Kilogram A lump of Platinum cylinder in International Bureau of Weights and Measures, Paris

24

Examples of SI units include:Can you give some examples of metric units?

• a. Volt (V) for voltage• b. Liter (L) for volume• c. Meters/second (m/s) for speed• d. Kilogram/meter3 (kg/m3) for density• e. Joule (J) for energy• f. Watt (W) for power

Converting UnitsConverting between metric units, for example from kg to g, is easy, as all it involves is powers of 10.

Converting to and from British units is considerably more work.

Example: given that 1 m = 3.28084 ft, this 8611-m high mountain is how many feet high.

28250 feet

Section Check

A car is moving at a speed of 90 km/h. What is the speed of the car in m/s? (Hint: Use Dimensional Analysis)

Question

A. 2.5×101 m/s

B. 1.5×103 m/s

C. 2.5 m/s

D. 1.5×102 m/s

90 km

hr

1000

1

m

km

1hr

60 min

1min

25 /

60m s

s

Order of Magnitude: Rapid Estimating

A quick way to estimate a calculated quantity is to round off all numbers to one significant figure and then calculate. Your result should at least be the right order of magnitude; this can be expressed by rounding it off to the nearest power of 10.

Section Check

Calculate approximately how many basketballs (diameter = 75cm) can fit in this classroom randomly AND orderly stacked one atop

the other?

• LET’S WORK ON WORKSHEET

SWBAT

Distinguish between accuracy and precision.

Determine the precision of measured quantities

Significant Figures reviewed

The number of significant figures is the number of reliably known digits in a number. It is usually possible to tell the number of significant figures by the way the number is written.

Some Examples:

23.21 cm has 4 significant figures

0.062 cm has 2 significant figures (the initial zeroes don’t count)

80 km is ambiguous – it could have 1 or 2 significant figures. If it has 3, it should be written 80.0 km.

EXAMPLE: A meter-stick is used to measure a pen and the measurement is recorded as 14.3 cm.

This measurement has three valid digits: two you are sure of, and one you estimated.

The valid digits in a measurement are called significant digits.

However, the last digit given for any measurement is the uncertain digit.

How many significant digits are in these

measurements?

a) 25.001 cm ________

b) 0.00012 kg ________

c) 35,000 m/s ________

d) 5.611 x 105 s ________

e) 0.0120 mm ________

f) 2.00 x 10-3 mL ________

g) 750 dg ________

Operations Involving Significant Figures

When multiplying or dividing numbers, the result has as many significant figures as the number used in the calculation with the fewest significant figures.

Example: 11.3 cm x 6.8 cm = 77 cm

When adding or subtracting, the answer is no more accurate than the least accurate number used.

CHECK!

Can you create ONE example each of addition and subtraction involving sig. figs.?

Check!Which of the following representations is correct when you solve 0.030 kg + 3333 g using scientific notation?

A. 3.4×103 g

B. 3.36×103 g

C. 3×103 g

D. 3363 g

Mr. Baldwin PHYSICS

Mathematics & Measurement 9/12/2014

Aim: What is the difference between precision and accuracy?

Do Now: (next slide)

Homework: Go to my webpage (www.whsad.org) and read up

on tomorrow’s lesson on Graphs

Ronald, Kevin, and Paul perform an experiment to determine the value of acceleration due to gravity on the Earth (980 cm/s2). The following results were obtained: Ronald: 961 ± 12 cm/s2, Kevin: 953 ± 8 cm/s2, and Paul: 942 ± 4 cm/s2. .

Read the following question and justify who gets the most accurate and precise value

A. Kevin got the most precise and accurate value.

B. Ronald’s value is the most accurate, while Kevin’s value is the most precise.

C. Ronald’s value is the most accurate, while Paul’s value is the most precise.

D. Paul’s value is the most accurate, while Ronald’s value is the most precise.

DO NOW

Answer: C

Reason: Ronald’s answer is closest to 980 cm/s2. Hence, his result is the most accurate.

Paul’s measurement is the most precise, it’s within 4 cm/s2.

The precision of a measurement is one-half of

the smallest division of the instrument used.

When a measurement is made, the results often are reported with an uncertainty.

Before fully accepting a new data, other scientists examine the experiment, looking for possible sources of errors, and try to reproduce the results.

A new measurement that is within the margin of uncertainty confirms the old measurement.

Comparing Results

• Accuracy: • How close you are to the

actual value

• Depends on the person measuring

• Calculated by the formula:

% Error = (YV – AV) x 100 ÷ AV

Where: YV is YOUR measured Value & AV is the Accepted Value

• Precision: • How finely tuned

your measurements are or how close they can be to each other

• Depends on the measuring tool

• Determined by the number of significant digits

Accuracy & Precision

Accuracy & Precision

• Accuracy & Precision may be demonstrated by shooting at a target.

• Accuracy is represented by hitting the bulls eye (the accepted value)

• Precision is represented by a tight grouping of shots (they are finely tuned)

Accuracy & Precision

Precision without Accuracy

No Precision & No Accuracy

Accuracy without Precision

Accuracy - Calculating % Error

• How Close Are You to the Accepted Value (Bull’s Eye)

Accuracy - Calculating % Error

If a student measured the room width at 8.46 m and the accepted value was 9.45 m what was their accuracy?

Using the formula:% error = (YV – AV) x 100 ÷ AV

– Where YV is the student’s measured value & AV is the accepted value

Accuracy - Calculating % Error

Since YV = 8.46 m, AV = 9.45 m% Error = (8.46 m – 9.45 m) x 100 ÷ 9.45 m = -0.99 m x 100 ÷ 9.45 m = -99 m ÷ 9.45 m = -10.5 %

Note that the meter unit cancels during the division & the unit is %. The (-) shows that YV was low

The student was off by almost 11% & must remeasure

Acceptable % error is within 5%

CHECK

• In the measurement, 86.21, the “2” is (certain, estimated) and (significant, not significant). The “1” is (certain, estimated) and (significant, not significant).

CHECKA 100-cm long rope was measured with three different scales. The answer obtained with the three scales were:1st scale: 99 ± 0.5 cm, 2nd scale: 98 ± 0.25 cm, and 3rd scale: 99 ± 1 cm. Which scale has the best precision?

A. 1st scale

B. 2nd scale

C. 3rd scale

D. Both scale 1 and 3

Answer: B

Reason: Precision depends on the instrument. The measurement of the 2nd scale is the most precise within 0.25 cm.