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# physics/math proble

### #1 Daniiel Posted 24 February 2007 - 09:26 PM

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Im in grade 11 and im doing physics at the moment.
We're learning about mirrors, concave, convex and stuff like that.
Ive been reading ahead because i dont have the greatest teacher and i came across a small problem.
Ive circled it here.
I dont understand how they got from that step to the next and where the 42 came from.
Did they round off the 10.5 to 11 then break it down.. then times the 7 by 6?
i know my theory is wrong but thats the only thing i could think of for it to possibly equal that.

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### #2 james_8970 Posted 24 February 2007 - 11:15 PM

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1/6=7/42
1/10.5=4/42

You probably learnt this way back when but the denominator has to be the same when you add and subtract a fraction.
That math book is dumb though, the point of fractions is to only have full numbers within, and not have unfull (or whatever you call it in english math) numbers If you need me to clarify this further just ask.
Back to calculus I go.......GAH!
James

Edited by james_8970, 24 February 2007 - 11:20 PM.

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### #3 Daniiel Posted 25 February 2007 - 12:17 AM

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ohhhhhh
that was a long time ago
i completely forgot i thought you just subtracted the bottom ones.
prettty stupid
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### #4 james_8970 Posted 25 February 2007 - 10:39 AM

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lol np, everyone has their blond moments.
James
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### #5 Mike Gee Posted 26 February 2007 - 09:54 AM

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Hi Daniiel,
42 is the lowest common multiple ( in this case, a number which both can be expressed as by integers) of 10.5 and 6, so you need to multiply the 1 over the 6 by 7 and the 1 over 10.5 by 4 to make them both come out as a fraction with 42 as the denominator.
The problem mixes decimals and fractions which can be a little confusing......
Come back to me if you need more help. Good luck with your assignment.

Mike.
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### #6 Daniiel Posted 27 February 2007 - 02:31 AM

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thanks for helping
hahah but have a read up a bit
i had a bit of a memory slip
but i have a feeling ill post a problem on here soon
in mathc im doing complex number systems
prettttty tricky
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### #7 SOORENA Posted 05 March 2007 - 06:46 AM

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Looks like they don't teach you the same stuff in every country. I'm also in grade 11, although I get that problem and can solve it, I haven't come cross it or anything else like it so far this year.
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### #8 Daniiel Posted 05 March 2007 - 07:24 AM

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ohhh
we're learning light at the moment
and finding the virtual/real images in convex and concave mirrors and stuff.
its not that interesting
but i guess they wouldnt start us off on nucleur physics
what are you doing in it?
the first few weeks we spent on like errors and stuff
percentage errors, absoluted and stuff like that
surprisingly all the smart looking kids failed the practice test
i passed along with 3 other girls
hahah weird hey?
weird because the smarter kids didnt pass

Edited by Daniiel, 05 March 2007 - 10:42 PM.

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### #9 sari Posted 05 March 2007 - 08:45 AM

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Are you implying it's weird that girls passed? I certainly hope not, because I don't like to see the myth that girls can't do math and science perpetuated.
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### #10 james_8970 Posted 05 March 2007 - 04:43 PM

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Lol, i'm finishing up grade 12 and have never come across light in my school. Can't believe how different the curriculum's are in some instances between countries, but i guess they can't teach you it all.
Sari, I think he's just stating that he and 3 other girls were the only ones thats passed in the class. If you(Daniiel) are stating otherwise, it'd be wise to edit your post.
James
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### #11 Daniiel Posted 05 March 2007 - 10:40 PM

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hahahah i didnt mean it to sound like that.
but i what i meant was
the people who i expected to pass failed.
i expected one of the girls to do better then me and she did
but the other 3 are really loud and act alot stupider then they are
ithe guys are pretty annoying aswell though
they have massive arguments about world of war craft and other rpgs like that
im sure its a good addicting game
but i dont see why you should argue about it. during class
im gonna try these math c questions out
i missed the class today because one of the teachers lied and i got a interschool suspention
which is where you sit in a room all day and have a 10 minute break
but aparently my teacher was stuggling to understnad it
his a smart guy aswell
the topic says
"Solveing Inequations"
they give you somthing like this
(x-1)(x-2) < 0
and you plot it out on a number line
then the equation is 1<x<2
im not sure i have a complete memory blank
its really confusing. like we get to one chapter then people behind us ask questions
then we go back and realise we've forgotten it all
and complex numbers
its confusing
ill take some pictures of it
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### #12 SOORENA Posted 06 March 2007 - 07:13 AM

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missed the class today because one of the teachers lied and i got a interschool suspention
which is where you sit in a room all day and have a 10 minute break

I know what those are, except ours go for the whole day, with no breaks. I got caught playing Quake 3 Arena Demo on Lan in school, when I was supposed to be starring at my teacher who was also playing games on his laptop!!!

Edited by SOORENA, 06 March 2007 - 07:14 AM.

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### #13 Daniiel Posted 06 March 2007 - 07:20 AM

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hahahah
mine go for all day aswell
but being a senior all day is from 9 - 1
so its pretty cool
there pretty easy to get past?
like i really needed t ogo to my classes today
and there built on fear really
they wanna scare the kids right?
if you act like it doesnt scare you, but you understand what there saying.
thats mature
so yeah i convinced them to let me out for physics
but i had to come back
i just stayed the whole lesson in chemistry
its pretty funny
you see these noisy grade 8s walk in
then 5 minutes later they look liek there about to cry
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### #14 james_8970 Posted 06 March 2007 - 05:01 PM

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If your having any problems with that math you had up there just give me a shout, its easy and I can very easily assist you with it. Ya the suspensions here are sitting in a 5x8 room with nothing but a desk, its from 8:30-3:45.
James

Edited by james_8970, 06 March 2007 - 05:02 PM.

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### #15 warriorscot Posted 06 March 2007 - 06:03 PM

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hehehe making you sit in a room all day, thats hilarious i can just imagine them trying that in schools here you would have a riot if they tried to do that, shutting you in a room all day im fairly sure isnt allowed here as well and even if they did you would have to have the same number of breaks as anyone else and i cant tell you if a teacher tried to stop most of the guys i went to school with from leaving when they wanted they would have got popped even the well behaved ones would have, punishments like that are totally against the ettiquete just not how the game is played the whole teacher and student relationship is a game of bending the rules and punishments and avoiding them. And a punishment like that for playing quake way overkill that ones a sending out the room maybe a punishment excercise or a bit of ribbing from the teacher which was always the most common with good teachers ritual embaressment is by far the most effective punishment.

Also try refraining from pressing the return key so much, the text will wrap so you can just type in proper sentences.
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