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if u want to strengthen ur concepts..try Interactice Physics...1 of the most reliable and well written books..also it has lots of good problems..dc Pandey also has lots of nice problems.. Cheers.
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Hi Kan, This function cannot be integrated and I'm 200% sure.  Cheers.
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Hi Arvind, First of all u try to solve a sum using the normal method. If it doesnt work use baye's theorem(BT). BT works for almost every problem. Cheers.
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Hi, I have a few that u guys may already know. Here goes :- 1) loss of energy in an inelastic collision = [m1m2 (v1-v2)2(1-e)2 ] / 2(m1+m2) 2) fraction of KE transferred in an elastic collision where ,m1=m; m2=xm =4x / (1+x)2 3) if a bullet or any body loses f fraction of velocity after every collision with a plank, then no. of planks required to stop the bullet=1 / (1-(1-f)2) 4) a body is projected from a step (stair has 'n' steps) of height 'h'and breadth 'b'. if the body hits the nth step, then square of projection velocity u2=ngb2 / 2h 5)  dx / x(1+xn) = (1/n) log(xn/1+xn) +c 6) IF cos-1x + cos-1y + cos-1z=pi, then x2+y2+z2+2xyz = 1 7) IF sin -1x + sin -1y + sin -1z=pi, then x (1-x2)+y(1-y2)+z(1-z2) = 2xyz8) IF tan-1x + tan-1y + tan-1z=pi, then x+y+z=xyz 9) tan-1(x/y) + tan-1(y-x / y+x) = pi/4 10) IF tan-1x + tan-1y =pi/2 or cot-1x + cot-1y = pi/2, then xy=1 Cheers.
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Hi Arun, Well, it is a bit difficult to answer ur question but I'll try my best. If u can manage to memorise the results of standard questions, that will really help (by standard I do not mean the basic stuff like ( (d/dx)sin x=cos x), but something like dx / x(1+x n) =(1/n) log ( x n / (1+x n)) , etc..). Basically wat I mean is learn as many tricks as possible. If u can do this u should be ok. But generally most students are not able to do it efficiently. In that case u need to be really good with ur concepts. The moment u see a sum, u must not waste time thinking abt it. Solve the sum with as less no. of steps as possible (avoid using unnecessary steps). This can come only with practice. If u can do the first method it is well and good (even bcz u do not have much time left i.e. assuming u r in ur 12th). Hope that helps. Cheers.
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Hi Kab, I'm dead sure. Cheers.
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Hi friends, Integrals of the form dx dx dx ------------- or --------------- or ------------------------ , etc (a+b sinx)2 (a+b cosx)2 (sinx+ a secx)2 can be solved by "integration using Differentiation". But the process is pretty long. Can u suggest a shorter, quicker method???? Cheers.
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Hi Kab, I don't know if u know the answer or not( i have a funny feeling that u do know - hey; no offence ). But the answer is that these 2 integrals cannot be found( assuming that the 2nd integral is e -x^2). Cheers.
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Hi Vinay, Say the body is at a distance 'x' from the centre of earth. So, F= ( GMmx) / R3 ( force due to a particle inside the sphere at a dist. r from the centre=( GMmr) / R3 ) The force mentioned above is towards the centre of the earth. But the +ve X axis is away from the centre of the earth (assumption). So force becomes= - ( GMmx) / R3 As F  -x, motion is simple harmonic in nature. If u still have confusions, plz reply. Cheers.
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Hi Rashmi, Let us take the example of our own sun. A day will come when the nuclear fuel of the star(sun) will come to an end. At the present situation the energy created due to the nuclear reactions on the sun is enough to counteract the gravitational force of the sun. Once the nuclear fuel gets over (this may happen after 4-5 billion years), gravity will take over and then the sun will begin to shrink. This will increase the density of the sun exponentially and this will also increase the escape velocity of the sun (currently the escape velocity of the sun is around 100 miles/second). So when the escape velocity becomes 186000 miles/sec i.e. 300000 km/s, then even light will not be able to escape the surface of the star (event horizon). This is the time when the star becomes a black hole (the intermediate stage is a white dwarf or a neutron star). The conversion of a star into a black hole is generally in the form of a supernova. A black hole is not entirely black (it was discovered by Stephen Hawkings). It constantly emits out microwave radiations. The matter gulped in by the black hole is constantly emmited in the form of energy radiations. BUT how do u think it is possible for matter to escape from the event horizon? For that to happen, the particle should possess velocity greater than the speed of light (which is impossible according to the TOR). This is explained by the "Uncertainty Principle". At some measurable point where the position of the object can be found out, the velocity of that particle cannot be measured. So at this instant the (relative) velocity may exceed the velocity of light and escape the event horizon and be emmited in the form of microwave radiation. Scientists believe that black holes lead to baby universes and they open out on the other side of the universe from WHITE HOLES(White hole does not allow matter to enter but only allows matter to exit; reverse of a black hole). The topic on Black holes is endless. If u wish to know more about them read books written by "Stephen Hawkings" or "Michio Kaku". Hope that clears ur doubt. Cheers and a Happy New Year.
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Hi Anup, Cheers and a Happy New Year. |
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Hi nunoxic, Even I donot agree with quite a few of the rankings, but Siddhanth asked for something and this was the best I had. I would appreciate if u could provide us with a more accurate and accepted info. And abt ur voice against Kanpur and Kharagpur, I think those 2 do deserve the 1st and 2nd spot.  And Admin(sir), wat do u mean by " alma mater"  Cheers.
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Hi Siddhanth, I'm not an expert, but I do have the data. Cheers and a Happy New Year to everyone.
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Hi Nishant , Is this the question ----> exisnx+cosx [ x4cos^3 x - xisnx + cosx] / x2cos^2 2x Cheers and a Happy New Year to everyone.
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Hi nabarko, Let length of rod be x. let the other force be f . So f - F=ma ------(1) net torque about centre of rod is 0; so F.x/2 = f . (x/2 - L) F.x/2 = (F+ma) (x/2 - L) ---from (1) After solving for x, we get x= { 2L(F+ma) } / ma Hope that's ok. Cheers.
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x ] [ 0] x / (sinx/2) = 2 / [ {sinx/2} / {x/2} ] = 2 ________ when x ][ 0] {sinx/2} / {x/2} tends to 1. Cheers.
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If u do ur CBSE flawlessly, u have a very good chance in AIEEE. As for BITSAT, CBSE will help, but it may not guarantee u a seat there. But if u know ur concepts and know a few tricks in solving each type of problems, u will have a pretty good chance there too. Cheers.
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Hi Mn _sn, Well let me tell u one thing; making a list of definitions will be of very less use (for JEE preparation) . Just read definitions and make sure u understand them. Coming to derivations; I think "practising" them is another way of wasting time . Go throu them once, make sure u understand the principles used,and then "memorise the results" only. Learn short ways of solving probs, learn new tricks. Once u r clear with the concepts ( concepts do not include "memorising" defns or derivatns), start solving problems. Remember, JEE exams test ur accuracy and speed. Make sure that whatever u attempt, u get them right. Cheers.
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Hi, Er.....what exactly do u want? Dont u think refering to books would be a better option ??? Cheers.
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