UPDATE (TUE 3:45pm): There is a lot going on at this point, so here is a list of what you have to do before the class on Thursday.
1. Read everything on this Class 10 blog and print the attachments (including the new one [in red] at the end of this red list.) PLEASE BRING YOUR SCIENTIFIC CALCULATOR TO CLASS.
2. Decide on eight projects from the handout from Sun 6:00pm that look interesting to you. THEY ARE ALL GOOD so don't agonize over them and worry about what they mean. Just pick eight of them that look like they might be interesting. Then mark each one with a letter (A, B, C, D, E, F, G, H). A is your first choice and H is your 8th choice. The reason to do this is that each student will draw a number from 1 to 8. The student with the 1 goes first to pick a project, 2 second, etc. So when your turn comes up, your highest choices may already be taken. If your A and B choices are taken, you will immediately select the next letter (C). Otherwise we are going to spend the whole hour with kids trying to figure out which project they want. If you can't select your project immediately when your turn comes up, I'll go to the next person and you'll drop back until you are ready. These are all great projects and you will do fine and have fun no matter which one you get. I wish I had time to do all the projects by myself, so I could have a lot of fun, too!
3. Please make sure you bring all 3 handouts to class. Thank you!
HANDOUT FOR THE CLASS MATH REVIEW:
https://sites.google.com/site/yhbscience/Class10.CLASS.recording.sheet.rev2.docx?attredirects=0&d=1
4. Please don't forget to do Homeworks 7 and 8.
HANDOUT (Sun 6:00pm): Here is the handout for class. Please read before class. :) Thanks.
https://sites.google.com/site/yhbscience/Class10.Science.Projects.using.Gravity.rev1.docx?attredirects=0&d=1
HOW TO DO HOMEWORK 8 and 7 and get 100% right on both. (Fri afternoon 5:40pm)\
To get 100% you have to do exactly what the steps below say to do. (The four people who turned in HW 7 yesterday -- thanks for being on time -- can print out a new copy and resubmit HW 7 to get 100%) If you want to learn more (and get a higher grade), you should resubmit using these instructions. :)
Yes, the instructions are very long, but that's because I am trying to explain very carefully, so you can understand (I hope!). We don't have enough time in class to explain everything.
STEP 1. Learn how to do a square and a square root on your calculator. Get someone to show you how. Then do these two tests to see if you really can do it:
-Find the square of 5.23 ANSWER 27.3529
-Find the square root of 85.333 ANSWER 9.2376
If you did not get both of these two answers right (ignore small differences in the last digit), go to the website
http://www.csgnetwork.com/squarerootsquarecalc.html
This is guaranteed to do squares and square-roots correctly. PLEASE USE THIS FOR ALL SQUARES AND SQUARE-ROOTS until you learn how to do them on your calculator.
HOMEWORK 7
First, write your name on all three pages. Then staple them together.
NOW, you can fill in the two columns for problem 1. (The square-root column wants the square-root of the square (in the middle column) that you just computed - NOT the square-root of the number in the first column. Just like my examples on the homework showed.)
STEP 2. The first blank says "N = ____" . What is N? N is how many numbers you have. In the EXAMPLE given in the HW, you had four numbers, (1,2,3 and 4) so N = 4 there (as the EXAMPLE shows). Now you have five numbers (1,3,5,7,and 9) so N = 5
STEP 3. Then it says "first ADD them" If you can't add the numbers in red above, please ask an adult. whenever it says "PLEASE ASK AN ADULT," Please ask her/him to read this blog so they will know all the steps I am giving you.
STEP 4. Next, it says "Then DIVIDE by N" If you can't divide the sum of the red numbers by 5, please ask an adult.
STEP 5. Then it says "The MEAN, M = _______ " This is what you got when you finished STEP 4. Just copy it here.
STEP 6. 3(a) asks you "Whose measurements are more accurate?" The numbers that are more accurate will be closer to each other. Look at your numbers and then look at Cheezy's numbers. It will be obvious which numbers are more accurate (closer to each other). If you don't understand, please ask an adult.
Then it asks "Whose SD should be smaller?" Did you read the instructions to problem 3. right above the questions? It says "The smaller the SD is, the more accurate the numbers!!" So whoever you said had the more accurate numbers will have the smaller SD (even though you don't know what the value of the SD is - you know it has to be smaller!). Both of your answers have to be the same, you can't answer YOURS for one of the questions and CHEEZY'S for the other question.
STEP 7. Now we compute means and standard deviations. NOTE - in the SD equation it has N/N-1. It has to mean N/(N-1). If it meant (N/N) - 1 that would be (1) -1 = 0 and all SDs would be zero! So if you are working with five numbers, N = 5. Then N/N-1 = 5/(5-1) = 5/4 = 1.25. That's where the 4 comes from. If you had 26 numbers (so N = 26), the fraction would be 26/25 = 1.04. Got it?
STEP 8. for Your DATA, N = 5 because you have five numbers (in 3(a)). Then you copy the five numbers from 3(a) into the five blanks under NUMBERS. Then you find the squares of each of those numbers, and write the answers in the five blanks under SQUARES. Here is the answer to the first one; you do the rest. NUMBER = 16.1 => SQUARE = 259.21 (exactly) NOW CHECK!! by taking square-root of 259.21: You get 16.1 back. THIS PROVES YOU ARE RIGHT!! Are you checking all of your answers before you turn in your homework??
NOW Steps 9 and 10 apply to both the column labelled NUMBERS and the column labelled SQUARES
STEP 9. For SUM you add the five numbers in the column above.
STEP 10. For MEAN you divide the SUM by 5.
STEP 11. FORGET about the equation for SD and leave the answer blank (unless you want to try it). Just go to the website I gave you:
http://easycalculation.com/statistics/standard-deviation.php
In the box above "calculate", type in the five numbers from the NUMBERS column with commas between the numbers, and then click "calculate". On the line in the homework where it says "As a check" copy the program's result for Mean (Average) into MEAN = ______________ and the results for Standard deviation into SD = _____________.
You are finished this part.
STEP 12. Repeat exactly the same steps (Steps 7-11) for CHEEZY'S DATA.
STEP 13. Answer 3(d) based on your new information. First answer the second part (Whose SD is smaller?) using the new results you just calculated for YOUR SD and CHEEZY'S SD (from the two lines beginning with As a check...) After you check whose SD is smaller, you can answer the second question in 3(d).
Then back up a line to answer the first question "Whose measurements are more accurate?" Remember that both questions must have the same answer, so circle the same one you circled below,
STEP 14. Now for Part 4 (at the end of it). Copy YOUR SD and N from 3(c) into the two blanks. To calculate SDM, just divide SD by SQUARE-ROOT of N. Since N = 5, this gives you square-root of 5 = 2.2361 (CHECK that of course) 2.2361 squared = 5.0000. Yes, it checks!!
So, SDM = SD/2.2361 and put it in the blank space. I don't mean write "SD/2.2361" in the blank, I mean substitute in the numerical value of SD you already calculated, and then after you do the numerical division, put the numerical result in the blank. Got it?
Repeat STEP 14 exactly to get the SD, N and SDM below where it says " and for Cheezy's results" You should now copy Cheezy's five measurements from 3(a) and then do the rest of the stuff in STEP 14.
*** You are finished Homework 7 ***
HOMEWORK 8 OK, let's do it! If you learned how to do HW 7 according to my step-by-step instructions, HW 8 should be pretty easy.
Start by writing your name on all 3 pages and then you can go to STEP 1.
STEP 1. The first thing is to write on the HOMEWORK sheet the data from EXPERIMENTs (EXPs) 1, 2 and 3 in the NUMBERS columns. To do this, you need to click on (and PRINT OUT) the attachment at the bottom called PENDULUM EXPERIMENTAL DATA
- Transfer the nine (POP QUIZ: WHAT DOES N EQUAL?) numbers (first number is 2.011, last one is 2.032) from EXP 1 on the attachment to the "NUMBERS for T(s) column" of EXP'T 1 in HW 8. Then transfer the nine numbers from EXP 2B (2.014 to 2.014) to EXP'T 2 in HW 8. Then transfer the nine numbers from EXP 3 (1.424 to 1.431) to EXP'T 3 in HW 8. (Don't worry about about EXP or EXP'T, they are both abbreviations for EXPERIMENT) (Don't worry about about EXP 2A data -- I did 2A and you did 2B and the results are close: mean = 2.00733 (me) and 2.01122 (you guys). The difference in your results and my results is LESS THAN TWO-TENTHS OF ONE PERCENT. REMARKABLE!!
STEP 2. Now, you fill out the rest of Part I exactly the same as in HW 7. At each step of the way, you can check your results against mine from the attachment. IF you can't get my results, then yours are wrong (I think :) ). So just copy my results where needed & write "COPIED" At least you will have something to think about. DON'T FORGET TO TRY THE TWO WEB CALCULATORS (For Square and Square root, and for mean and standard deviation) GIVEN ABOVE BEFORE YOU COPY. BUT DON'T WORRY IF YOU HAVE TO COPY, JUST THINK ABOUT YOUR ANSWERS & MINE AND SEE IF YOU CAN FIGURE OUT WHY MINE MAKE MORE SENSE. Ha Ha.
STEP 3. PART I. Ratio of bob masses = 69.0 g/19.6 g = you tell me :) <-- answer 1
Ratio of mean periods = 2.01122 s / 2.01256 s = you tell me :) <-- answer 2
Now do "A change in bob mass...." (put ans. 1 in 1st blank, and ans. 2 in 2nd blank).
NOW you have to think a little. See the first 2 numbers in the EXAMPLES ? If your mratio = mass ratio (ans 1) is near 4 (3.5 would be considered near 4 because it is almost 90% as big as 4) and your Tratio = period ratio (ans 2) is near 1, then you choose "none" - it means the period doesn't change when the mass changes. If you got something near 4 and 4 you would choose "proportional", and so on.
The others are the same idea. For your home experiment (by the way, I found that dental floss makes a great string for pendulums -- it doesn't break), when it says "home 2" and "home 1" it means the 2nd home experiment (90 degree swing) and the 1st home experiment (10 degree swing). 90 degrees means the string starts horizontal. To measure the 10 degrees, you can use the angle protractor in the handout I gave you (see blog) or you can use tan(10 degrees) to figure out how far to pull the bob sideways when you start. For a 20 inch string, you have to pull it 3.5 inches to the side, then let go. If you want to do it in cm, then for a 50 cm string, you have to pull it 9 cm sideways and let go.
HAPPY SWINGING!!
PENDULUM DATA. (Thu night) Here are four data sets. I did two (Expt 1 and 2A) and you did two (Expt 2B and C). Your measurements were EXCELLENT! Congratulations. You can tell by how small your SD was -- and this is what tells how accurate the numbers (measurements) were. Your numbers were accurate to 0.013 seconds. That means 13 thousandths of a second!!! [My two runs (1 and 2A) were accurate to 0.010 and 0.013 seconds.]
This should help you check your homework. Some of you need to ask somebody how to do a square and a square-root on your calculator.
When you do the experiments at home this week to determine the effect of different swing angles, it will be better if everybody uses the same string length, so let's all make the distance from the pivot point to the center of your bob = 50cm (L = 50cm), just like your last experiment in class. To convert cm to inches, divide by 2.54. This will give you 19 11/16 inches (almost 20 inches). Ask an adult to check this out before you do your experiments.
https://sites.google.com/site/yhbscience/Class9.PENDULUM%20EXPERIMENTAL%20DATA.docx?attredirects=0&d=1
-Mr Frank
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