i hope it was clear that the properties ( energy n momentum) of particle of light (i.e photons) is related to properties (wavelength n frequency) of its wave character.

see, u know light has both wave n particle character . depending on situation one of d two dominates.phenomenon like interference can b understood only in terms of wave theory. but particle theory is used to explain phenomenon like photoelectric effect.these r just background knowledge .

when u look at properties of photon(which r d particles of light,) u can find a relation. like

1.  if a light wave has frequency 'f' n wavelength 'd' (suppose), then when d same light behave as particle the energy of the a single photon is given by        

                              E=hf   or hc/d  , where 'h' is Planck constant , n 'c' is speed of light.

 and its linear momentum is given by

                              P=h/d  or E/c

also all the photons of light of a particular wavelength 'd' have same energy n linear momentum given by the formula given.

i hope dis is one of the way u can find a relation between them.

i think op aggarwal

if u r interseted u can better search space n time on google

see acc. 2 einstein d universe is made of 4 dimension time being one of them. for imaginig it u can consider it like a carpet .near any heavy celestial bodies 4 e.g. sun thir is depression formed at this space. in relativity thr is no diff. bet space n time.infact acc. to einstein  gravity is not a force like other forces. earth doesnt move around sun due to gravity . earth travels a straight path in 4-dim. of space n time. but appears to us to move along circular orbit in 3-dim.  in this way einstein considerd time as a dim. thr is a very famous book 'a brief history of time'  by stephen hawking   .if u get a chance go thru it . it is nice n will certainly make u doubt d way u see d world .

to tell u smthing even more weird , acc to string theory thr r 11 dimension!!!!!!!!! .  many people r working over it n many rejects it. it still has got no conclusion.

i think ans for collision problem is a)0 bcoz momentum remain conserved in collision .

initially in hor. dir. P=mu

                   in vert. dir. P=m* underroot 2gh (u=0 a=-g y=h dr4 v2=u2-2gh  gives you v=underroot 2gh)

 after collision d vertical impact of ball has no effect on hor. motion of d block. surely d vel of ball will change bcoz. the collision is inelastic. but i dont think vel of d block will change . hope im ryt

see first understand d diff. between them.

static friction- dis force acts on the body by the another body in contact when it is just about to slide but has not  started d motion yet. it is also called limiting friction . it adjust itself accordingly to equal itself to any external force applied in order to start d motion. but thr is an upper limit of its magnitude.

in other words                         f <or = kN  , where k=coeff. of static friction.

kinetic friction- in acts on d body when thr is relative motion between the two bodies in contact .

in dis case                          f=kN          , k=coeff. of kinetic friction.

coeff of static friction is always greater than kinetic . u have to judge frm d given condition dat which of them is being exerted on d body . n remember one thing ,   a body exert only one force on an another body in contact which is called contact force n which is d resultant of normal force n frictional force between their common surface in contact .

once read d theory of hc verma. ur doubt will get clear.

see i v solved all previous yr ques. papers of aieee n found dat its is becoming tougher n heading 2wards lesser no. of ques. dis yr was really a surprise 2 find assertion reason ques. dat resemble wat comes in iit. might b next yr d ques r even lesser. b prepared 4 everything. all d best

do join a test -series . brilliant last date is over . u can go 4 fiitjee . but do join. see u r not joining any coaching thn if u r not very disciplined u ll get lethargic. test series is a must . many provide online test. bansal provide home based test. see dont waste time now. hurry n enroll 4 any of these now . fiitjee is a bit tougher but is given by large no. of students so u ll get 2 know ur true position . thr is resonance also . all d best

i mean dat sm people recommend 2 solve only few ques. frm irodov . all ques. need not b solved.( sm ques. r much above d level dat we need 2 practice).  sm teachers mark those ques. in coaching classes. if u know which of them can b solved plz write d ques.no. here.

i suppose last date 4 submission of form is in sept. ( it was when i d given in 06) . i think u r applying 4 SA stream . u can also apply offline by sending request 4 application form. do check its site . i dont know wat u mean by "wats req?"      . ..............in oct/nov. u ll b having ur written exm . cover ur 11th syllabus . atleast mech, algebra, chem was mostly frm 10th . bio also 10th level . if u qualify in dat ,(result i think come in 1st week of dec) u ll b called 4 interview.  but seats r really very few.  ALL D BEST.

thnx 4 ur advice , but sm say dat only few selected ques. shud b solved frm it . neone plzz point out those ques .

anyone plz write d ques. no. of selected problems dat can b solved frm irodov.

anyone please write d ques. no. of selected problems dat can b solved from irodov.(at least frm mechanics)

i know a bhaiya who did chemical frm iit . he has a pack of abt 5lpa in reliance

anyone sure abt pattern of iitjee 09 .???do we have screening n mains dis yr?