Phys 271Principles of Physics

Download the following files:Syllabus

All the documents are available at the website:http://www2.swccd.edu/~hlee

IntroductionWilfred Hok Kong LEE, Ph.D.

Office: 343AMail box: MSE Office 215

Contact Info:Email: hlee@swccd.eduPhone: ext. 5533

Mon 11:45-1:30 Tue 1:15-2:00 Wed 11:45-1:30 Thu 1:15-2:00

Textbook & Course HomepageOptional: University Physics with Modern Physics with MasteringPhysics (13th edition) by Young and Freedman Course Homepage:http://www2.swccd.edu/~hleeLab manuals will be posted on this site. Print out the lab manuals BEFORE you come to class.

Your scores will be posted on Blackboard Online:Go to the Southwestern College homepagehttp://www.swccd.eduClick on “Online Class Login” under “E-Tools”

GradesLab Report 80%Final Exam 20%

100 – 85% A84 – 75% B74 – 60% C59 – 50% D49 – 0% F

Policy on CollaborationYou can work in groups, but you must write your solution independently.

Students who copy or allow people to copy your work will get zero.

Attendance, tardiness, cell phones, pagers, etc…

You may be dropped from this class

If you are coming in late…Classes start on the clock

Don’t slam the door and your backpack!Don’t disturb the others, be quiet

Sign up on the “Black List” if you are late more than 10 minutes. Ten points deducted from your next homework.

Lab Report (every 1-2 weeks)1. Name, ID & Date2. Title3. Purpose4. Procedure 5. Data 6. Equations7. Mathematical calculations8. Sources of Error9. Conclusion

Name and Date

Write your name on the top right hand corner

Include the names of your group members if you worked in a group

Write the date you performed the experimentNOT the date you write the lab report nor the date it is due

TitleInclude the title of the lab. You may choose an appropriate title if you wish.

PurposeA description of what the lab is about. In your own words. Do not copy and paste please.

Procedure• Step by step• No need to say “push button [D]…”• Instead say “use computer to measure velocity…”• Don’t say “take data” unless you say what the

“data” is, e.g. velocity, voltage.

Tips: Include diagrams

DataThis section must contain all the data you obtained in this experiment. You can present it in a table format. You can use the tables provided in your handout. Always include units and use scientific notation when convenient.

Equations and CalculationsThis section must contain equations and calculations you used. Please be clear and organized. Show your work. I don’t want to see just the final answer. If there are more than one trial, show work for just one of them.

Multiple Trials• If there are multiple trials, the calculations for

each trial are almost exactly the same. • No need to write the calculations for every trial. • Do a sample calculation for one of the trials.

Indicate which trial you are calculating, seeing that the calculations of one trial is correct, I will trust that you know how to do the rest.

Sources of ErrorNo experiments are perfect

Unacceptable sources of error:“I may have did the calculations wrong”“I was careless”

Common errors:Friction, reaction time …

ConclusionProvide a summary of the experiment. Compare your results with the theoretical value, if applicable.

Conclusion always has something to do with the purpose section.

BE QUANTITATIVE!!!

Examples of ConclusionsAcceptable“the measured value is within 4.7% of the accepted value”. “Newton’s Second Law is verified to within 3%”. quantitative

Unacceptable“the measured value is pretty close to the accepted value”, or “Newton’s Second Law is correct” too vague

QuestionsPut your answers to the questions on the lab manuals after the conclusion section.

Staple EVERYTHINGYou lose points if you don’t staple your work together!!

Some (very) simple error analysisFor those who are interested:http://www.upscale.utoronto.ca/PVB/Harrison/ErrorAnalysis/http://www.ligo.caltech.edu/~vsanni/ph3/

You can download notes about data analysis from these sites.

Percentage differenceOften one wants to compare two numbers, e.g. u=12.4 and v=13.1 by evaluating their percentage difference.

Both are correct. Usually when we calculate percentage difference, the two numbers are very similar in value, so it does not matter which one we put in the denominator.

Some common mistakes

The “%” sign is NOT optional, nor is the absolute value sign.

Mean (average)Repeated measurements:

Common mistake:

Too many digits

Usually, the mean has only slightly better precision, so keep to at most one higher significant figure. The mean above should be either 3.3 or 3.

Standard deviation σ

The smaller the standard deviation, the more better are your data.

ExampleFind the σ of the following measurement of length x:11.3cm, 11.7cm, 12.0cm, 11.8cm

Standard deviation

68% of probability lying within a width of 2σ.

TipsAlthough it is often not asked explicitly, it is usually a good idea to compute the standard deviation to see how far your data are apart from each other.

You will get a better grade!

Linear plot

Example:a = g sinθ

Plot a vs sinθ. The slope will give g.