welcome to Physics 352!

2009 - 2010 Syllabus   and   Course Expectations   and    the official time
Honesty /Safety /Tardy/ClassComputer Use/Cell Phone policies


Walker1  & Walker3 websites

AP Physics and FAQ/practice AP problems  and  North Carolina Physics Curriculum

How Stuff Works! and How Things Work   

 
Monday,
November 2
Tuesday,
November 3
Wednesday,
November 4
Thursday,
November 5
Friday,
November 6
class
 last one of the trimester

physics survey

have you sent me your homework score......
(see email from today)
(the maximum number is, I believe, 105 which includes 5 points for bring gravity-law properties to class that day it was assigned)

please send this today!

it's supposed to be clear skies for the next 4 nights (including tonight);
a great chance to figure out which way the moon goes around the earth!

election day







finally, the return of the second lab book sometime tonight
(or early tomorrow)
 Amnesty Day

3:30 - 5 pm ONLY

if you have labs that werent graded, come IN PERSON with your lab book(s) and show me what lab did not get graded.... be familiar with the lab so that you can convince me that you did all parts

tutorial help from physics teachers will be available most of the day

schedule is posted on the physics floor
physics final exam sometime

do you know where?
students leave town

faculty are chained to their desks grading and writing comments
what we'll do
in class
practice chapter 7 problems




reading
(always done
before class)
 7(4)
one new concept:
power!

STUDY the solution to last week's problems 9(20) and 9(28) on my bulletin board to see how to conserve momentum even if there are net forces acting
 
 
 
 
in-class
presentation
remember the BAN on using dvat formulas on today's homework!

7(22)





written
homework
(by 5 pm)

7(66, 24)

the peekskill-meteorite-hit car went on an international tour (Tokyo, Paris, Munich...) in the late 90s
 

 
 
lab
 lab A11 due
 
 
 
 
other
did you know (from having done last week's experiment) which way the moon revolves around earth ?

post one of your practice problems (or QUESTIONS (many of you need practice on the QUESTIONS!) from
chpater 12
chapter 7
or
chapter 9
by 8 pm today


have you started practicing for the final exam?
I hope so!
you should be doing 3 problems -- tht would mean about 45 minutes) each day (starting this past weekend).... one on each of the three kinds of problems we have done this trimester
(you needn't pick new problems.... for practice, pick a problem that you did earlier.... because then you'll also have a solution from earlier in the year that you can compare to.... and don't worry, you won't rememner that you had done the problem earlier anyway!)

 
 

 
 
Monday,
October 26

more gravity questions

Tuesday,
October 27
Wednesday,
October 28
Thursday,
October 29
Friday,
October 30
class
bring completed A10 to class today 

questions that arose in either C or D or maybe even both:

if you were paying attention to the real world last week, you know that the discovery of 32 exoplanets was announced

this brings the number of planets known outside our system to nearly 400

how did we discover these planets AND determine their mass -- via Kepler's 3rd law -- if we can't even see them?

when (what day) does the earth move fastest around the sun?
(block C doesn't care, but maybe block D does)...
what is special about the earth-to-sun distance that day?

(someone in) block D knew that the orbit period of most earth satellites is about 90 minutes.... how would we calculate that from Kepler's 3rd law?
what does this have to do with the non-book problem you turned in yesterday?

how do artifical satellites (in movies) creat artifical gravity for its occupants?
why is there a minimum size for a such a satellite that results in your apparent weight being equal to your normal earth weight?

still unanswered in class.....

1) does the speed of a satellite (around a given star or around a given planet) increase or decrease as the satellite moves farther out?

   how do you decide?  it should be pretty easy to calculate based on what we have done already.... a nice question for the upcoming final
....
(if you want to show me your answer after you work it out, i will be happy to confirm....)

2) does the gravitational field increase or decrease as you go inside the earth?
what is g at the earth's center?
how do you know?.... here's a hint that will help you figure it out.

 let's say we want to find the gravity force on you if you are inside the earth
at distance d from the center... (which is less than the radius of the earth dRE)....
what part of the earth's mass exerts a force on you?  only the earth's mass that is closer to the center than you
are!  (i.e., only the part of the earth whose distance from the center is < less than d!)....

if you assume the earth has constant density, you should now be able to figure out how g depends on d

(if you want to show me your answer after you work it out, i will be happy to confirm....)
 
 a REQUIRED experiment:

at some time tonight (or tomorrow or the next night) check out the position of the moon in the sky.....

then, tomorrow, or the next or the next night....
do the same thing (note the position of the moon in the sky) AT THE SAME TIME OF DAY as the first observation....

what will this tell you?
the direction that the moon revolves around the earth!

what the heck have you been doing at night for all these years?!?!?!?

start experiencing life!
 
 
what we'll do
in class
start our 3rd kind of problem.....

work on Lab A11

reading
(always done
before class)
a fairly chunky reading assignment.... don't wait till sunday night...

and have  you noticed how many chapters we're covering this week?


 9(1 up to -- but not including example 9-1)

then 9(5 up to -- not including -- example 9-5)

then 9(4)

what is momentum;
when is it conserved?
was momentum conserved in lab last friday?  be careful.....!
9(2, 3)

especially the example of the hail and rain


















 9(7)
 7(1)
7(2) 
in-class
presentation
12(29)



finish up the problem we didnt finish in class Monday

the revised (to one dimension) example 9-6

master the 7- (or is it 8-) step method


9(17)



9(13)
written
homework
(by 5 pm)
12(8)
read problem 12(59) after you're finished

&

suppose that you live on the earth's equator.... what would the rotation period of the earth have to be for your apparent weight to be equal to 50% of your true weight?


 
9(20)



9(28)
 
 9(27a, 57)


lab
obtain your Lab A11 collision with partner either today or tomorrow so that you have it at the start of wednesday's class

labs A5, A6, A7AD, A8, A10  should all be completed (with conclusions written)...
they will be handed in tomorrow by noon
lab books due by noon 
 
 
 
other
 has your dorm room obtained its copy of TWTW?

 
 

   
 
Monday,
October 19
Tuesday,
October 20
Wednesday,
October 21
Thursday,
October 22
Friday,
October 23
weekend of October 23- 24
class
students return

teachers have a work day
  test advice 
test on all of forces
(dvat's may be included
of course), including force labs


last day on gravity 
we do lab A10
what we'll do
in class

satellites,
artifical and otherwise

more on satellites, orbiting, & Kepler's laws....

we do lab A10;
there is a very short prelab

put the data table in your lab book spread evenly across two facing pages

reading
(always done
before class)
 
have read 12(3) up through the bottom of p. 373
after you returned last night

things to know:
1) left-over from last friday:
if gravity up at the space station is 9.5 m/s2,
why are those astronauts weightless?

2) why is "microgravity" the dumbest word ever?

3) did they do a good job in following our force-diagram procedures in the three examples they did
a) beginning at bottom of page 369 and ending in mid-page 370?

b) example 12-4

c) active example 12-1

what do all three examples have in common?

 
 12(3) again?

know Kepler's laws
(yes, as in "by heart")

what (physics) is the 3rd law in disguise?
(what about the other two?)



(if you want to show me your answer after you work it out, i will be happy to confirm....)

read the lab A10 lab handout


 
still unanswered in class.....

1) does the speed of a satellite (around a given star or around a given planet) increase or decrease as the satellite moves farther out?

   how do you decide?  it should be pretty easy to calculate based on what we have done already.... a nice question for the upcoming final
....
(if you want to show me your answer after you work it out, i will be happy to confirm....)

2) does the gravitational field increase or decrease as you go inside the earth?
what is g at the earth's center?
how do you know?.... here's a hint that will help you figure it out.

 let's say we want to find the gravity force on you if you are inside the earth
at distance d from the center... (which is less than the radius of the earth dRE)....
what part of the earth's mass exerts a force on you?  only the earth's mass that is closer to the center than you are!  (i.e., only the part of the earth whose distance from the center is < less than d!)....

if you assume the earth has constant density, you should now be able to figure out how g depends on d

(if you want to show me your answer after you work it out, i will be happy to confirm....)

in-class
presentation




12(29) will now be monday's show and tell....
instead, show and tell is the prelab for today's lab

written
homework
(by 5 pm)
Friday's homework has been graded and is available for pick-up from the black box in front of my office
 

 
 12(25, 33)

lab
 if you missed the lab practical last week, let me know as soon as possible when you're back and can take it....
 you can keep your lab books to study for the test, but all forces labs should be finished, with written conclusions
(that's A5, A6, A7AD, and A8)
 
 
 

other
wlak-around quiz solutions posted....

did you practice calculating with really big or small numbers on your calculator?
did you waste time putting 3 or more significant figures into the calculator or did you save time (and avert mistakes) by using only 2?
check the stray paper envelope for YOUR papers.... there are sure a lot of them in there... which means some people can't be tracking their homework averages.... yes, I know who you are...

put up 1 of your practice problems on the bulletin board, in preparation for the test tomorrow.....
deadline 8 pm
if you are not planning on taking the test today, i need to know why (and when you're taking it) as soon as possible 
 even problem solutions are on the bulletin board just outside the classroom door... have you noticed?
have you looked at the syllabus (link at top of this page) lately?

how many more chapters are scheduled to be done this trimester?

how many days are left this trimester?

     
 
Monday,
October 12
Tuesday,
October 13
Wednesday,
October 14
Thursday,
October 15
Friday,
October 16
class
it's a wednesday 
 
 it's a mini-Monday
 
 


what we'll do
in class

finish the friction lab: A7D;
bring your lab book

we do lab A8c,
the acceleration of elevators



cars


deconstruct Newton's gravity law



gravity problems



lab practical !!

bring your lab book; wear lab clothes; calculator, etc.  required for entrance
reading
(always done
before class)
have you read everything in chapter 6 ?
 example 6-8, again

what  forces did they leave out?  in what directions?
12(1)....
gravity is no longer down
(necessarily)
12(2) 
 
in-class
presentation

6(47 & 48b)


bring a list of the important features of Newton's gravity law

12(16)
(yes, a force diagram and net force equation, etc etc is still required, even though we have a new force)
written
homework
(by 5 pm)
due AT THE BEGINNING OF CLASS:
prelab to elevator lab


due at 5 pm with the in-class presentation:
6(50)
 
6(81),
6(83)
 
  12(14)

and yes, 12(14) still requires a force diagram, and a net force equation

12(21a)....
yes, force diagram, net force equation, .... (see the trend?)
the algebra can be either easy or complicated (depending on YOU!)
for my sake, please make it easy)
lab
 you and partner should have completely finished part A of lab A7....
it should be ready to hand in

if you STILL haven't had your prelab for A7D graded, did you leave me your lab book this past weekend?
 
 
 elevator and friction labs should be finished
 
other
 
have you picked up
The Way Things Work from the book room?
(one copy per dorm room)
test on forces
1 week from today

have you been doing enough practice?
that will eliminate silly mistakes, such as
a) wrong angle when breaking up forces into components
b) missing subscripts on masses in multi-mass problems
c) violating step 3
(which includes the interludes) of force-diagram procedures
(this is an especially horiffic mistake)

some excellent practice problems:
6(27,  75, 73, 67, 84, 90, 94)

also 6(62, but also find the magnitude and direction of the acceleration while sliding)
6(40, except find the coefficient of static friction necessary to keep the masses from moving)
5(62)
 walkaround quiz 3 shown to me
(THIS TIME.... I will only look at it once! be ready!)
in person
(by 5 pm.... please don't wait until the last hour)...
problems 6(37, 38):

a) find the acceleration of the two masses when the coefficient of kinetic friction of between the incline masa and incline is 0.10

b) find the coefficient of static friction necessary to prevent the blocks from moving


Monday,
October 5
Tuesday,
October 6
Wednesday,
October 7
Thursday,
October 8
Friday,
October 9
class
 
 
 
 
 
what we'll do
in class

problem 6(11)
&
demonstration
examples of static friction

problems 6(7)
and
5(44)

lab A7 parts A and D

horizontal circles:
the plane! the plane!

reading
(always done
before class)
 finish 6(1)

know the properties  of static friction 
 
 
 section 6(5) up through the bottom of page 164
(horizontal circles!)

circular motion
KNOW the magnitude and direction of circular acceleration....
did they prove either/both of these?
how?
finish 6(5)
(vertical circles)
in-class
presentation
6(4) but only the part about kinetic friction

6(4) but only the part about static friction
6(10)
written
homework
(by 5 pm)
6(1)
&
6(2)
 
prelab to
lab A7 part A in lab book
(yes, the one with A5 and A6; it's the only book you should have)

prelab to lab
A7 part D
also in the same lab book
 
6(76) EXCEPT change the angle given to 35 degrees!

6(79)
lab
 

by 8 pm:

 
lab A6 poster (one side) due on  the bulletin board
(AND in your lab book):
include

1) data table of ordered pairs

2) linearized graph
with linear fit

3) 5 column matching table
(the last two columns of the matching table are
expected value of the fit parameters
(slope & intercept)
&
% difference between actual fit parameters and expected fit parameters

4) conclusion

5) statement/signature by all participants that work was shared equally

posters available by the black box
 
 
 
other
have you finished the cat-picture and wedged ball problems? 
finish the coffee-cup problem

meditate on the email I sent you
 
coming attractions:

forces test: wednesday october 21

   
 
Monday,
September 28
Tuesday,
September 29
Wednesday,
September 30
Thursday,
October 1
Friday,
October 2
class
students on vacation

teachers have classes, or worse, meetings
 
enter lab A6
into your table of contents
(same book as lab A5)
 
 


what we'll do
in class

finish problem 5(16);
we've already done the force diagrams; come ready to write the force equations

our first inequality problem, 6(22)


lab A6 

the cat picture, 6(26)




the Garabage Gobbler

&

the wedged ball,
6(33)

reading
(always done
before class)
 
example 5-4 when you come back monday night; it's ONE page


for those who didnt last friday:
section 6-4 up to but not including example 6-6


lab A6
 

we will be doing 2 different labs simultaneously (although each group only will be doing one)
KNOW each of the 2 experiements (what's the independent variable? what's the dependent variable?) because you won't know which experiment your group is doing until mid-class

see more in lab block below
force triangles:
section 5(5 and 7)


 

6(1, only up to the "static friction" section)....
know the properties and laws of KINETIC FRICTION....
warning: there may be parts that you might disagree with?

&

first half of the
Guide to Perfect Force Diagram Solutions
in case you want more copies.... Columbus Day soon approaching... they make excellent Columbus' Day gifts


in-class
presentation


prelab to lab A6  done in the lab book

for the prelab, we don't want you to do the full seven-stop force-diagram method..... instead, try to arrive at the solution by answering the questions in the prelab....

we think it should take 5 minutes



5(51)
written
homework
(by 5 pm)

 
by 8 pm:

5(6 part a only)....
assume that the parachute no longer exerts tension on the parachutist (because the chute hit the ground before she did) during the de-acceleration by the ground

this is our first problem that combines d-v-a-t with a force diagram problem
(since you are probably doing the dvat first, remember the rules for definition of positive for force problems... and you may NOT change positive in mid-stream-problem)
 
5(58), the grocery bag, our first inequality problem

+

6(72); our first force-triangle problem...
the only force diagram, net force equation, etc. is for the rope, right?
but be careful of the question it asks
lab
 
 
bring prelab completed to class; it asks you to determine the acceleration of the system
&
put data table in lab book across two ENTIRE pages
 questions i would be happy to hear your answers for about lab A6:
1) what quantity is your group going to plot on the horizontal axis?

2) what quantity is your group going to plot on the vertical axis?

3) what are the math and physics equations that will describe your fit?

4) what is the numerical value of the independent variable (the quantity on the horizontal axis) of your first run?
 lab A6 poster will be due next Tuesday
other
 

LAST CALL:
have you picked up your 4 book cover sheets from my black box if your book doesnt have them?
 
have you finished the cat picture (good algebra practice), 6(26)

and the wedged ball (good trig practice), 6(33)
problems ??

pages for september 2009
pages for august 2009