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vertical motion under gravity
Particle projected from th etop of a cliff

there r two cases:
when particle is projected upwards ; vertical distance from point O at t = h
then
1. if it is above the point O h=ut-1/2gt2
2.if it is below O -h=ut-1/2gt2

can u explain the second case for me ?? where did the "-" sign cum from if it's throwing upwards ??

n how do u derive the equation
t=u/g+root(u2/g2+2h/g)

using 1/2gt2-ut=h ? (it should b h=ut-1/2gt2 but this is the eqn. given in FIITJEE..plz tell me how this eqn is correct too)

Help me out soon plz..

Anu.

i saw IIT 2007 papers in narayana institute's website. but now i can't find it there bcuz they have uploaded AIEEE papers instead.
can u give me the link of any website that offers downloading of iit 2007 pprs ?
i tried fiitjee n brilliant website. couldn't download it properly from the website of brilliant. n i can't find the pprs in fiitjee site also.
Plz help as soon as possible

Q. Violet light lambda=400oA of intensity 4 watt/m-sqaure falls normally on a surface of area 10cmx20cm.Find
the energy received by the surface per second.
the answer is 0.08J
can u tell y the formula
E=1Acostheta is used to get the answer ?? shouldn't theta b 90 then, so wouldn't the expression bcum zero ?

i spotted a line in my material : "electrons are emitted only if the frequency is greater than the threshold frequency"
won't electrons b emitted when the frequency is equal to threshold frequency (they have to b emitted..is the statement wrong?)???

can u tell me y, in the concept of stopping potential, when the polarity of the battery is reversed, the electrons are retarded ???
and
1. why is the stopped potential dependent on the metal?
2. why doesn't it depend on the intensity of light?
3. why does it depend on the frequency of light ?

finally one more question :-
A small plate of a metal(work function=1.17eV) is placed at a distance of 2m from a monchromatic light source of wavelength 4.8x10 power -7 and power 1.0 watt. the light falls normally on the plate.Find the number of photons striking the metal plate per square metre per second.

-ananya.

fwks_phoenix@yahoo.com

If a straight line through C( - root 8, + root 8) making an angle of 135 with the x-axis cuts the circle x=5costheta, y=5sintheta, in points A and B, find the length of the segment AB.

we get the radius as 9 or -1 using the eqn of circle n parametric eqn. of circle.
But how to find the length of the segment AB ?
in the solution it's given as AB= 9-(-1) . can sumone explain this step for me ??

thanks in advance...

if f(9) = 9 and f ' (9)=1 then

_{[ x]}

_{[ 9]} { 3 - f(x) } / {3 - ^{[2 ]}

x } is equal to ???

---------------------------------

differentiate the numerator n the denominator...
u'll get " - differentiation of f(x) " in the numerator n " - differentiation of x to the power 1/2" in the denominator

now u sub. the value for x as 9..
u'll get " -1 / - 1 / 2 X 3" = " +6 "
so i think the ans qil b " + 6 "

bcuz in this the valence electron lies in 4f14
f is the outermost...
s is the innermost...

The difference in electronegativity between the two atoms that form the molecule helps us identify the polar nature... the diff. in electronegativity should b greater than 2 or 3....

<<Electrophiles are electron deficient, so neutral electrophile will be with incomplete octet, e.g., AlCl3, BeCl2, SO3,

Nucleophiles are electron eich species, so neutral nucleophiles are those which have lone pair of electrons, e.g., H2O:, :NH3, RO:H, RN:H2>>

how do u find out if it's got imcomplete octet or not ?

How can u identify neutral electrophiles and neutral nucleophiles ?

hyrdation proceeds by protonation of olefins to form carbocation, followed by nuclephilic attach by water...
can someone explain this process for me ?

@ramya

for A(h,k) B(m,2-m) C(p,2-p).

wouldn't slopeAB= (2-m-k)/(m-h) ???????

m=y2-y1/x2-x1right ?

i think the answer is B....

the first statement is correct....
when u divide the equation that u get by using conservation of momentum by the equation that u get by using conservation of energy(kinetic) u'll get the first statement.....

ok..so only 3,4 n 6 marks...

did the 6 marks have negative marking too ?

3 marks, 4 marks, 6 marks n 10 marks right ?

thank u for answering...