Messages posted by krishna.gopal

You have used 25% and 28% ammonia in your problem. I an taking 28%

Consider 100 gram sample. It must be made by mixing 28 g of ammonia with 72 g of water.

17g of ammonia reacts with 18 grams of water to make 35 gram of ammonium hydroxide

So amount of ammonium hydroxide formed is (35/17)*28 = 56.6

So percentage of ammonium hydroxide is 56.6%

Mass of truck A = 40 kg

Velocity of truck A = 5 m/s

momentum of truck A = 200 kgm/s

Mass of Truck B =50 kg

Mass of boy on it = 10 kg

Velocity of truck B = 10m/s

Momentum of truck B and boy system = 600 kgm/s

Just after the first jump

momentum of first truck = 200 kgm/s (same as earlier)

momentum of boy = 10*12= 120 kg m/s (Assuming 2m/s is velocity relative to truck B)

momentum of truck B - 600-120 = 480 kgm/s

Velocity of truck B= 9.6 m/s

After boy landing on truck A

Momentum of Truck A boy system = 200+120=320 kgm/s

velocity of truck A and boy system= 320/50=6.4 m/s

Momentum of truck B= 480 kgm/s (same as earlier)

velocity of truck B= 9.6 m/s

Just after jump of boy from truck A

momentum of boy = 10*(6.4+2) = 84kgm/s (2m/s is velocity relative to truck A)

Momentum of truck A = 320-84=236 kgm/s

Velocity of truck A = 236/40 = 5.9 m/s

Velocity of truck B= 9.6m/s (same as earlier)

After boy lands on truck B

Velocity of truck A = 5.9 m/s (same as earlier)

Momentum of truck B and boy system=480+84=566 kgm/s

Velocity of truck B and boy ystem = 564/60 = 9.4 m/s

So I think final velocity of B is 9.4 m/s

Good work Mansi

Good work Yahiya

HI talktome_diya. I don't thick fluoroscence and phosphorescence is any where related to IIT JEE or any other engineering eneterance exam

Right ruhi

For an electromagnetic wave. IA polaried can do it (because if there is no electric field in one direction then there can't be magnetic field in perpendicular direction)

But in general i don't know about anything where polarisation happens because matter does not allows magnetic field to pass in one direction

When maxima of one corresponds to minima of other. This happens when path difference is of the order of (0.5)(589.3)^2/(0.6) nm

This length is called coharence length and is given by (lamda average)^2/(2*delta lamda)

HI Tipra sorry for delayed reply. The idea is to apply Bernolli's equation between a point on liquid surface and another on the opening. If the gauge pressure Pg (8*10^5Pa) and height of liquid is h(1 m) The velociy of water(v) from the hole will be sqrt (2*g*h +Pg/d) where d is density of water.

a) If H is the height of platform (2 meter) then water will fall at a distance of v*sqrt(2H/g)

b) Vertical force = mass flow rate * vertical velocity on striking ground = (d*A*v)*sqrt(2gH) where A is area of hole

c) Force on tank = mass flow rate * horizontal velocity on exit = (d*A*v)*v

Hi Ashish how do you get 5^2163 by putting x=1. 1+2x-3x^2=-1 and not 5 for x=1.
And very good answer Yahiya

Color in this complex come because of d-d transition in chromium atom

Take a special case. Consider numbers 157 257 357 457 557 ....957. Removing left digits of this number will give me a number which is divisible by 57. But for all these numbers sum of digits is different. So what exactly are you looking for in the answer

HI rammy wrong answer that is formulae for pH of a salt of weak acid and weak base. pH =0.5pKa -(0.5)log(C) for weak acid and 14 - 0.5pKb +(0.5)log(C) for weak base (C is conc of acid or base)

Another thing that will be important is how boy is jumping. Is he jumping in forward direction or in backward direction or in some oblique way. Because answer will vary according to that

See adinand there is nothing like magnetic field lines in this world. t is imaginary lines that we draw for ourselves which just show the direction of magnetic field. So you may draw as many magnetic field lines as you want. But as number of lines that we can draw is finite there will always be gap. But you can draw magnetic field lines in the gap as well (And there is nothinng wrong with it)

As far as your second question goes no one has an answer for that (As why magnetic field decreases as we move away from magnet, or simillar questions like why gravitation field decreases as we move away from earth and even if it decreases why ot decreases by r^2 ). We do not know WHY things behave in some particular way. We just know HOW things behave.

For the third part, the way we have represented magnetic lines there density is proportional to magnetic field. So magnetic field is decreasing and distance between magnetic lines is increasing are two different ways of saying same thing

Intensity is power/area. So if light is coming from a point source As the distance increases area increase by d^2. This means energy will decrease by a factor of d^2 as mentioned by Aditya

See Manmadha, You have to consider shell with some finite thickness, because then only you can talk of charge inside and outside the shell. Now inside this finite thickness the elcetric field should be zero. So if make a Gaussian sphere which lies inside that thickness of outer shell, then net flux through it is zero.
This means net charge inside that gaussian surface is zero. If inner shell contains charge q then inside of outer shell must contain +q

Very good answer Kusum

Capacitance of one capacitor =KA(epsilon_not)/d
K=4
A=pi*r^2=3.14*10^-4 m^2
d= 10^-3 m
C=1.11*10^-10-11 F

For 100pF we need nine such capacitors and hence 18 such metal foils. SO i feel no answer is correct

Magnification of 100 means two points seperated by unit distance will appear to be seperated by 100 units in microscope.

If thikness of hair is 3.5 mm in microscope, its true thickness is 3.5/100=0.035mm

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