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Catalogs Discussion Forums -> Mechanics -> Rotational Mechanics; rates assured -> Go to message
This Post 35 points    (Olaaa!! Perrrfect answer.   in 7 votes )   [?]
5 replies   

look ill give u the soln. to a general case....


the free body diagram is as posted below.......let the mass be 'm' the length be 'l'........let 'N' be the normal force which the rod experiences from the bottom..............." " be the coeff of friction..............


analysing rotational motion abt the pt rotation....ie the pt of contact with ground............


mgcos *l/2 =ml2/3 * ...........................1)     Torque abt pt P


so we have =3gcos /2l.......................2)


analysing accleration of centre of mass in horizontal direction.....


max=N..............3)


analysing acceleration in vertical dirn....


mg-N= may........................4)


but we know that ay is nothing but component of accn of c.m in vertical dirn........and as no slipping.....


accn of c.m= *l/2........


thus ax=*l/2cos................................5) 


and ay=*l/2sin ..................................6)


so using 1, 2, 3, 4, 5 and 6 and solving for


we get....=




here u can substitute theta as pi/3 to get the reqd. result....


from the above eqn.s solve for  and the 2 accns wud be l/2 and l respectively...(interms of g)


ill try to post the free body diagram...


hope it helps...


rate if useful....

Catalogs Discussion Forums -> Mechanics -> Time taken for collision? -> Go to message
This Post 17 points    (Olaaa!! Perrrfect answer.   in 4 votes )   [?]
8 replies   

look by symettry i can say that they collide at the midpt.....proof: there is no shift in cm of the system(ext F=0)


so evn towards the end the centre of mass will remain at the midpt only...assume the midpt to be the origine....and the two particles at (D/2,0) and (-D/2,0) respctly....the force eqn for particle at origine will be sumwat like this....


- mVdV/dx = Gm2/(2x)2....if it is at a dist. 2x frm the other mass...it will be at a dist of x frm origine...


integrate it frm D to 'x' and frm 0 to V....write V as dx/dt and u know wat 2 do(integrate frm 0 to 'T'..and frm D to 0) and T is ur time taken....jus. giving the brief mtd...


hope it helped


rate if useful......

Catalogs Discussion Forums -> Mechanics -> Angular momentum? -> Go to message
This Post 15 points    (Olaaa!! Perrrfect answer.   in 3 votes )   [?]
2 replies   

if it is falling due to its own weight then how can u conserve L??


u cannot conserve L becoz of the simple reason that there is a net external torque....arising due to the gravitional force....acting on the centre of mass towards the centre of the earth which is responsible for its rotation....hmm one thing that u can do is to conserve mechanical energy....ie mgL/2 (1-cos@) =1/2 I w2.....and put cos @ to be 4/5 to get the reqd. answer....(pardon ne silly mistakes...) this is the rough method....


rate if useful....

Catalogs Discussion Forums -> About IITs and JEE -> plz....help required urgently.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
3 replies   

yaar summore replies plz....

Catalogs Discussion Forums -> About IITs and JEE -> plz....help required urgently.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
3 replies   

frnz ...my AIR is 4322...i have my councelling tomorrow...


plz tell me what happens in the counclling.....what shud i apply for and what can i hope of getting....this is especially for those that have experienced the councelling......replies reqd. urgently.....

Catalogs Discussion Forums -> Mechanics -> irodov problem no. 1.316 -> Go to message
This Post 25 points    (Olaaa!! Perrrfect answer.   in 5 votes )   [?]
5 replies   

applying bernouli's theoram for water flow thru' the 2 surfaces S1 and S2.......


P1+ hdg  + 1/2dv12 = P2+ hdg  + 1/2dv22............where h= the height from the, the two surfaces are located....


P1=P + H1dg........and P2=P + H2dg.......P=atmospheric pressure...


applying we have dH g = 1/2(v22-v12)


but we have from eqn. of continuity S1v1=S2v2


applying this we have SV =


rate if useful......

Catalogs Discussion Forums -> General -> my altitude metre not working.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
3 replies   

thanks a lot mate....thats just about what i required to know.....thanks a lot.....lets get sum expert views on this one...

Catalogs Discussion Forums -> General -> my altitude metre not working.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
3 replies   

Sirs... i have a problem with my altitude metre....ive got many got many salutes coming in today and were not accounted for in my altitude...ive tried contacting the admin and a few moderators in this matter...but none of them have shown interest in it yet....so plz help me out in sorting out this issue......

Catalogs Discussion Forums -> Lounge -> thoughts,,,,, -> Go to message
This Post 50 points    (10 Olaaa!! Perrrfect answer.   in 10 votes )   [?]
130 replies   

Ok....when it comes to motivation...a lot of us need it despirately.....when it comes to inspiring lines there are a few that i always make......


" what ever u do....always maintain a CALM MIND.........for a calm mind can even overcome a storm"


"U wanna see a miracle??....BE THE MIRACLE....."


"He who has achieved success without facing defeat even once is the bigest goofer.....failure is the first and the most important step to success"


" fruit of hardwork and efforts is the sweetest of all times....itna hard work karo ki sabko phodke rakhde!!"


" Kabhi kabhi kuch paane ke liye kuch khona padhta hai......jo haari hui baazi ko jeete wahi baazigar kehlata hai"


and finally.....if u feel that u are a looser jus. becoz u have not done well in an exam like JEE or EEE or BITS or CEE or CET or UPTU or VIT (tab toh u shud feel happy) or WBJEE or for that matter any exam....lemme tell u that according to the philosophy of life...a man doesnt prove himself to be a winner just by faring well in a 3hr out of the many decades that he lives.....(im seriously telling it is true)so all the best and take care of urself....aur bohut time hai yaar zindagi main....


~~~~~~~ALL THE BST~~~~~~~~


rate if useful....

Catalogs Discussion Forums -> Algebra -> some really good Q.s.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
5 replies   

good mtd mudit...although a rough procedure...a nice one......


and akku....superb soln. to that integration one....and about that vectors one.....ur soln is 16d2/(a2+4b2+9c2)......the answer is 8/7{options are 8/7 7/8 1 4}.....(the fact that these are unit vectors is perhaps missed out).....but i am jus. thinking...using this identity(cauchy-schwartz if i amnt mistaken) how do we make use of the fact that these vectors are coplanar.....neways i feel like kicking my self for missing out on that(identity)....neways rated u ppl....

Catalogs Discussion Forums -> Electricity -> The pote.dif. bet. d terminals of a battery of emf is 6V & resistance 1ohm drops to 5.8V w -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   

assume the resistance to be 'r'


pot. accross internal resistance = 6/(1+r)


so total pot. = 6 - 6/(1+r) = 5.8


or 6r/(r + 1)=5.8


or r= 29 ohms


rate if useful....

Catalogs Discussion Forums -> Algebra -> Number of divisers of the form 4n+2(n>=0)of the int. 240 is a)4 b)8 c)10 d)3 -> Go to message
This Post 19 points    (Olaaa!! Perrrfect answer.   in 5 votes )   [?]
4 replies   

here goes the technical solution...


240 = 2431 51


we want factors of the form 2(2m+1) so we want odd multiples of 2....


so out of four powers we want only one 2.....rest to be choosen frm 3 and 5....


i have two objects 3 and five...total no of selections that i can make....


so total no of ways = (exp of 3 +1)(exp of 5 +1)= 2*2 =4


rate if useful.....

Catalogs Discussion Forums -> Algebra -> some really good Q.s.... -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
5 replies   

ppl......i was jus. trying these probs today.....mere palle nahi pad rahe the in many of these....jus try it out....


1) if A and B are the roots of the eqn. tanx = 2x.........find the value of -1S+1sinAx . sinBx dx  (A,B>0)


2) find -3S+3x8{x11} dx (my formula edittor isnt working)


3)the pts represented by vectors a,b,c and d are coplanar and (sinA)a + (2sin2B)b + (3sin3C) -4d =0


then, find the least value of sin2A + sin22B + sin23C


4) find the domain of f(x) =loge(3(pi)x - x2 - 2(pi)2 - sinx )


try it out and nudge if u get it......

Catalogs Discussion Forums -> Algebra -> No of Soln. of [X square +Ysquare]=1 where [.] denotes greatest integer function -> Go to message
This Post 9 points    (Olaaa!! Perrrfect answer.   in 3 votes )   [?]
2 replies   

actually it is a ring with inner radius 1 and outer radius 2 and centre at origine....or the intersection of


x2 + y2 >= 1 and x2 + y2 < 2


but if u are looking for integral solutions.....we have (1,1)...(-1,1)...(-1,-1)..and (1,-1)


actually i didnt get a very clear picture of ur Q.

Catalogs Discussion Forums -> Electricity -> physics challenge1:rates assured -> Go to message
This Post 10 points    (Olaaa!! Perrrfect answer.   in 2 votes )   [?]
3 replies   

INPhO 2000 if i amnt mistaken......dekho..when i first saw the Q. this is all that i cud figure out.....


assume that there is a sphere and we are depositing charge over it uniformly on its surfare.....


assume there to be a charge q already and we are adding a charge of dq......work done to do so will be


dW = Kqdq/R..........integrating from 0 to Q


and W = KQ2/2R


this is stored as potential energy of the system


so when u splitt into 2 equal spheres.i assume that the total volume is unaltered......so


4/3pi R3 = 2 * 4/3pi r3


or r= R/21/3......


and the energy of  first sphere = E = KQ2/R + TA1........(A1 and A2 are the surface areas of the first and the second 2 spheres)(TA= energy due to surface tension)


where T= surface tension of water...(given in the value list and not used in any other problem)


and energy of the smaller sphere = U = KQ2/4(R/21/3) + TA2


and for this change to be feasible we need E = 2U


equating which and solving we get Q and for 3 bubbles i guess u shud do it using r= R/31/3


and E = 3U....


third part main mere palle nahi padh rahe(dielectric break down)


but i have given a very brief method for the first 2 parts.....


correct if wrong....


rate if useful......

 
 
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