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 مسابقات نفسيات
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Solve the initial value problem:
(ye^xy-1/y )dx + (xe^xy+x/y^2 )dy = 0 ; y (1) = 1
99.99$ will be awarded to the one who solve 75% of the probelm.
we wish to see the bord adminstration,abo baker, el sadig, tagreed el sara ya zoul and all contrbuting with their views.
wa bab el negash maftoo7.
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Re: مسابقات نفسيات (Re: نفسيات)
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I will try my best :-)
M = ye(xy) - 1/y, N = xe(xy) + x/y2
¶M/¶y = 1*e(xy) + y*e(xy)x + 1/y2
¶N/¶x = 1 * e(xy) + xe(xy)y + 1/y2
Thus, exact.
¶F/¶x = yexy - 1/y
¶F/¶y = xexy + x/y2
F(x,y) = ò yexy - 1/y¶x
= exy - x/y + C(y)
¶F/¶y = xexy + x/y2 + C'(y)
C'(y) = 0
so C(y) = C
Example
(2x2 + y)dx + (x2y - x)dy = 0
(Solution) M = 2x2 + y, N = x2y - x
¶M/¶y = 1, != ¶N/¶x = 2xy - 1
Cases
1. dy/dx = P(x)Q(y)
2. dy/dx + P(x)y = Q(x)
integrating factor m(x) = eò P(x)dx ???
d/dx(m(x)y(x)???) = m(x)Q(x)
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Re: مسابقات نفسيات (Re: نفسيات)
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el sadig
you deserve the 100$
but you need to answer part B of the question in order to get the check mailed to you.
here is the second question:-
How much heat per hour do humans dissipate?
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Re: مسابقات نفسيات (Re: نفسيات)
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usually somewhere between 2200 and 4000, but 2000 Using a simple conversion (1000 calories = 1 Calorie, 1 calorie = 4.1868 J), amounts to 8.37 x 106 joules ingested per day
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 Re: مسابقات نفسيات (Re: Elsadiq)
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صباح الخير يا ورود
الصادق!!! دي جديده ما قلتها لي .. انا عارفه إنك شاطر في حاجات تانيه
لكن طالما كده انا حاجزه الكرسي الجنبك في إمتحان الشهاده الحيعملو لينا بكري
أتفقنا
 )
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Re: مسابقات نفسيات (Re: Elsadiq)
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el saidg
are you physicist?
you surprised me....
but le me hit you with the the first question part C.
lol
Does a black hole violate the Law of Conservation of Matter/Energy?
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Re: مسابقات نفسيات (Re: نفسيات)
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part C:-
all matter and energy falling into a black hole increase its mass with the energy converted into mass via Einstein's E=mc2 we call it Hawking radiation
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Re: مسابقات نفسيات (Re: Elsadiq)
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El sadig
you answer is right but let me add something to it:
Neither the existence nor the behavior of black holes violates conservation laws. All matter and energy falling into a black hole increase its mass, with the energy converted into mass via Einstein's E=mc2.
The eventual "evaporation" of black holes via the emission of so called Hawking radiation reverses the process, changing mass into energy, but the total mass and energy of the system is still conserved
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Re: مسابقات نفسيات (Re: نفسيات)
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السؤال الثاني
we can use the law of exponential Decay here :-
If y is a differentiable function of t such that y > 0 and y ' = ky then y = Cekt
C is the initial value of y and k is the exponential growth occurs when k > 0, and exponential decay when k < 0 let y represent the mass in grams of the plutonium because the rate of decay is proportional to y, you know that y = Cekt where t is the time in years. to find the values of the constants C and k, apply the initial conditions using the fact that y = 10 when t = 0, you can write 10 = Ce0 which implies that C = 10
by using the half life fact that y = 5 when t = 24,360, you can write
5 = 10e24,360k
1/2 = e24,360k
(1/24,360)ln 1/2 = k
y = 10e-0.00028454t
Since you want to find the t when Pu-239 is 1, you set y = 1. Then 1 = 10e-0.00028454t
t = 80,922 years
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Re: مسابقات نفسيات (Re: نفسيات)
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lets go to our next question.
i hope this time we get more contrpution.
Why does heat and cold make things expand and contract ? Also why do some metals expand more than others?
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Re: مسابقات نفسيات (Re: نفسيات)
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حاجاوب ليك دي بس غير شوية من الفيزياء و الرياضيات شوف جغرافيا تاريخ عربي وغلوتيات حبوبات هههها
When a material is heated the kinetic energy of that material increases and it's atoms and molecules move about more this means that each atom will take up more space due to it's movement so the material will expand When it is cold the kinetic energy decreases so the atoms take up less space and the material contracts
Some metals expand more than others due to differences in the forces between the atoms and molecules such as iron
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Re: مسابقات نفسيات (Re: Elsadiq)
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elsadiq...
am surprised...no wonder u r a great programmer. physics and calculus are things that i dont love to hear about after classes, but u realy made me interested somehow
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Re: مسابقات نفسيات (Re: Yaho_Zato)
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LoOOooOOOooOOooL
El sadig
im so bad in geography and history, i remember when i was in high school i used to cheat in the history and geography exams, i take the whole exercise book with me in the examination room and hide it under the desk.loooooool
i was always geting 90s in these classes, but i dont know nothing on them.
LOOooOOoooOOOooOOOoooooOOOoooL
and sorry for the late reply i was so busy.please keep the post up if i disapeared for sometime,dont just be like astudent answering the questions,loooooool, give us some knowldge from what you have to get up from our illitracy.
love and peice.
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 Re: مسابقات نفسيات (Re: نفسيات)
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salamz....ana gaitoo gadda calc. 2 last yr ... wa 1 zatoo i passed bil taltalaa...fa 7ajawib al million shaheed dee, YEMKIN tadrab ma3ay... ma3a inoo almemory is gettin weak wa ma 3arfaa asawee laihaa shno... i think it's ALGAZAEER< ALGERIA>>> .....wa maaa 3arfaa al million shaheed mno..lakin momkin a7awil atzakar al gadoo al 7arakaa
take good care till laterz,
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Re: مسابقات نفسيات (Re: zaytoona)
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it was el gazayer long ago.
but now its sudan.
count how many people died in the war since our independence in the south?
i bet they are more than a million.
mush kida?
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Re: مسابقات نفسيات (Re: نفسيات)
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Two people sitting in your run-of-the-mill supersonic airplane such as the Concorde can easily carry out conversations, without much trouble. If the plane is not accelerating, and they didn't see the outside through the windows, they could hardly tell they are in an airplane.
Why is this so? This is because the air is at rest inside the cabin. It is being carried forward by the airplane just as the passengers are. Since sound propagates in air, and air is at rest with respect to the speakers, everything will operate just as well as it does in your living room. (Equally well in first class and economy class, I might add.)
I will expand the discussion a bit though: Suppose we did something quite hard to do in practice and took off the top of the cabin so that air at supersonic speeds travels throughout the cabin. And we also assume that people can breathe, stay alive, and even speak under these conditions. In that case, can they speak to each other or not?
What happens in this case is, the sound from any source propagates not in all directions, but only in a cone backward from the source. The opening angle of this cone depends on the exact speed of the aircraft. The faster the airplane, the narrower the cone will be
We can make the following observations:-
1.To hear someone, you must be in their "cone of speech". This means that you definitely have to be behind them, and preferably not too much to the side.
2.If you hear someone, they definitely do not hear you. So, no two people can carry out a conversation without moving. (Try drawing two cones, facing the same direction, and such that each contains the vertex of the other.)
3How much you scream really makes no difference.
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Re: مسابقات نفسيات (Re: نفسيات)
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why do i answer my questions my self?
ma 3aleena
lets go to our next Question.
Why do you hear a glugging sound when you pour a liquid out of a bottle by holding it upside down?
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Re: مسابقات نفسيات (Re: نفسيات)
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let me take a shot, lakin 7atjeeni nafseeyat jad if i got this wrong wa inta kaman ma sadait khashmaak wa fada7tanee gidam al board kulu...3ashan kida go easy on me..
z giglin sound is z result of gas release, i dunno..i think it's oxygen, but in chem. class karahoona bil sayin that whenever there's a chemical reaction takin place, most likely the gas released is hydrogen (bs da when there's a chemical reaction takin place)... fa hassa i'm kinda lost as 2 which 1 it is, 7agoo amshee ajarib,wa a7awil ashkhat laya feehoo 3ood kibreet hehehe....
khalas yakhee, i'll go wit hydrogen..k??...
laterz now,
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 Re: مسابقات نفسيات (Re: zaytoona)
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ma jeet malak??... hope u r k,.... just askin...n i'd b prayin u r k, n comin 2night...or may b soon...
take care till laterz,
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Re: مسابقات نفسيات (Re: zaytoona)
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wow
i cant belive my eyes.
my post is still a life
heey zaytona
happy eid to you
i was in sadui arabia for haj
i just came yesterday.
how is every thing going with you.
thanks for asking.
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Re: مسابقات نفسيات (Re: نفسيات)
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heeey.... allah yakhalek, mabrook al 7aj,hope u enjoyed ur time wa kida... i asked 'bout u a couple of times, n u didn't show up...b3dain bainee wa bainaak, al shamar katalnee 2 know if i got z right answer or no, lakin inta ma baradtaa laya batne asloo x(...aha yalla next time u tell me, k??
till laterz,
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Re: مسابقات نفسيات (Re: نفسيات)
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i'll try to answer, hope its what you looking for.
lol
The Earth gains mass each day as a result of incoming debris from space. You may have even seen evidence of this activity in the form of a "falling star", or meteor, on a dark night.
While the actual amount of added material depends on which study you look at, an estimated 10 to the 8th power kilograms of in-falling matter accumulates every day. That seemingly large amount, however, IS insignificant compared to the Earth's total mass of almost 10 to the 25th power kilograms.
In other words, Earth adds an estimated one quadrillionth of one percent to its weight each day. I don't know of any counteracting mass LOSS mechanism of any consequence.
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ها؟؟؟؟ (Re: نفسيات)
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دب شنو؟؟احنا ما قد الجكايات دي يا الصادق و نفسيات
شوية شوية علينا ما تعملوا لينا نفسيات عليكم الله
الفينا كافينا...ولا شنو شباب....مش تخلونا دي احنا لسة علينا النجاح في الثانوية العامة-الله ينجحنا السنة دي-
:Pthe_girl
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Re: ها؟؟؟؟ (Re: the_girl)
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The Girl
dont you have interest in math and science?
the purpose of this post is to get more knowldge from other people, im sure alot of people have interest in this kind of posts, we are just their students.
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ما شاء الله (Re: نفسيات)
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ما شاء الله ما نسحركم انت و الصادق علي العطاء الجميل دي
انا يا بتي غير الكتب المفروض اقراها ...و اللي بتستهويني ما بحب
لكن بصراحة ما شاء اللة..الله يدومكم علينا نعمة يا رب
من اسة الامتحانات انا معاك انتو الصادق
the_girl
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Elsadiq
Yaho_Zato
فيس بوك
تويتر
انستقرام
يوتيوب
بنتيريست