Physics, Chemistry, Mathematics Forums

I had 2 small doubts, please clear them.

1. A person's skin is more severely burnt when put in contact with 1 gram of steam at 100^oC than when put in contact with 1 gram water at 100^oC. Explain.

2. What is the specific heat capacity of (a) melting ice (b) boiling water ?

A small cesium plate kept at a distance of 20cm from a large metal plate having a charge density of 1 nano coulomb/m² .A monochromatic light  of  wavelength of 400 nm is incident on the cesium plates. Work function of cesium plate is 1.9 ev.Consider  the fastest electron emitted parallel to the large metal plate.Find the displacement of this electron parallel to it's intial velocity before it strikes the large metal. 

what is the integration of e^x/x?

I have some doubts in electro magnetic induction:-

1) two circular coils have their centred at the same point. the mutual inducatance between them will be maximum when their axes are:

a) perpendicular to each other

b) at 60 deg

c) at 45 deg to each other

d) parallel to each other

2) In a uniform magnetic field of induction B a wire in the form of a semicircle of radius "r" rotates about the diameter of the circle with angular frequency "w". The axis of rotation is perpendicular to the field . if the total resistance of the circuit is "R", the mean power generated per period rotation is :

3) In a L-R circuit , just after the key is closed:-

a) a current starts flowing in the circuit

b) a potential difference is developed across the resistance.

c) e.m.f developed across the e.m.f of the battery

d) a heat is dissipated in the circuit.

What is the concept of integration in solving physics problems.

Please tell me as soon as possible.

For any material,how does the specific heat capacity C is calculated practically?

FOR fitting window frame can't we choose such material which has same coefficient that of glass.If yes give example?

In hole expansion we can say that hole is expanding,although whole every ring expands,but when metal surface is given heat the hole can expand by changing its shape.SO can now also we can say only that hole is expanding? 

I had a small doubt as follows:-
Given that (delta T_f) is the depression in freezing point of the solvent in a solution of non-volatile solute of molality m, the quantity

lim _m-->0 (delta T_f/m) = ?

Please tell me the right ans. with explanation, I don't know the ans. It was asked in jee'94.

1. If integral of Isin xI dx from a to b = 8  and integral of Icos xI dx from 0 to a + b = 9, then find the value of integral of x sin x dx from a to b. Answer is given as:  -2(2)^1/2 pie .

2. Please evaluate the integral e^{-a square * x square} dx from 0 to infinity. I am not getting ans.for this also. Well, answer is given as: (pie)^1/2/ 2a.

3. This question seemed difficult to me, please see:

Integral of Mod{cos(cos^-1x)/sin(sin^-1x)}dx from

cos(cos^-1alpha) to sin(sin^-1beta)

Answer is given as (beta - alpha)..............Please try these.

We cannot move a finger without disturbing all the stars.Explain.

Newton` Law is said to be an approximation to Kepler`s law.Why?

What is the radius of the sun?

In ammonia producing plant the N and H left unreacted are sent to recycled along with the more amount of N ,H why?

AT equilibrium,rate of F and B reaction are same.Does it include temp. also?