Monday, September 20, 2010
Mon-Day 2
Physics - EXTRA HELP tomorrow morning (and after school, if desired); to prepare for this week's test, bring questions from the end of the packet that you find difficult.
We discussed the lab write-up: good news that most of you consistently put the unit of each of your measurements- that will always be a good and necessary part of your correct answer.
Some of you did not heed the warning about the misused term experimental "error"- that NEVER means "mistake" in science. When a scientist makes a mistake, the experiment is ruined- it is never written up or published.
Experimental "error" REALLY means "SOURCE of random variation/ uncertainty". That is, an experiment done PERFECTLY by you or a perfect robot/droid STILL will have variation in the EXACT same measurements each time the SAME experiment is performed. Scientists must acknowledge, think about, and MINIMIZE sources of uncertainty in a given experiment. The FEWER sources of uncertainty, the BETTER the experimental design, and the more precise the results can be.
We went over the two hw problems and then did a problem in vectors 5 that shows the MAXIMUM and MINIMUM resultant magnitudes from adding any two vectors: the max is the sum of the two magnitudes ( zero degrees between the two vectors) and the minimum is the DIFFERENCE of the two magnitudes (180 degrees between the two vectors); the resultant can be ANY magnitude between the maximum and the minimum, depending on the angle between the two vectors.
We will finish up vectors 5 tomorrow and then do some test prep for the exam on Wednesday (part 1, multiple choice) and Thursday (part 2, written response).
The questions will closely match those from the packet and the labs; of course the numbers will be different, and the wording of the questions can vary- but that won't be a problem if you always DRAW a picture of what is in the question, and properly label everything with the correct sign and arrow direction.
AP Chem - we did some double replacement equation writing, including acid-base neutralization. Remember, all weak acids are written as un-ionized molecules, which almost ALL of them are (in solution).
We did a few percent composition problems, and then explained how the law of multiple proportions was discovered and applied to determining empirical formulas of compounds.
We discussed the lab write-up: good news that most of you consistently put the unit of each of your measurements- that will always be a good and necessary part of your correct answer.
Some of you did not heed the warning about the misused term experimental "error"- that NEVER means "mistake" in science. When a scientist makes a mistake, the experiment is ruined- it is never written up or published.
Experimental "error" REALLY means "SOURCE of random variation/ uncertainty". That is, an experiment done PERFECTLY by you or a perfect robot/droid STILL will have variation in the EXACT same measurements each time the SAME experiment is performed. Scientists must acknowledge, think about, and MINIMIZE sources of uncertainty in a given experiment. The FEWER sources of uncertainty, the BETTER the experimental design, and the more precise the results can be.
We went over the two hw problems and then did a problem in vectors 5 that shows the MAXIMUM and MINIMUM resultant magnitudes from adding any two vectors: the max is the sum of the two magnitudes ( zero degrees between the two vectors) and the minimum is the DIFFERENCE of the two magnitudes (180 degrees between the two vectors); the resultant can be ANY magnitude between the maximum and the minimum, depending on the angle between the two vectors.
We will finish up vectors 5 tomorrow and then do some test prep for the exam on Wednesday (part 1, multiple choice) and Thursday (part 2, written response).
The questions will closely match those from the packet and the labs; of course the numbers will be different, and the wording of the questions can vary- but that won't be a problem if you always DRAW a picture of what is in the question, and properly label everything with the correct sign and arrow direction.
AP Chem - we did some double replacement equation writing, including acid-base neutralization. Remember, all weak acids are written as un-ionized molecules, which almost ALL of them are (in solution).
We did a few percent composition problems, and then explained how the law of multiple proportions was discovered and applied to determining empirical formulas of compounds.
# posted by C @ 9:17 AM 
