pulkit

What do u mean by saying its based on averages ?

thanx for the help ....

You need a lot lot more advanced calculus than limits and diffrentiation even to start tackling pronlems of quantum mechanix.

1. What is observed if a>g?

It is known that the normal force and the apparent weight are negative, what does it mean?

Since force equation is vectorial, you need to see direction and can't just apply F=mg+ma, it can also be F=mg-ma.

There is nothing like negative weight, in case of acc > g, the man still falls with acc g, henece he will lose contact with the floor and move upwards, eventually hitting the cieling. The very concept of apparent weight is redundant, as the man in his refrence frame will not feel any force pulling him down, instead rather he will feel being pushed up.

2. What's the normal force? I do not totally understand this word.

When two bodies are in contact, the force they feel due to each other perpendicular to contact plane is called normal force. It is equal and opposite on both bodies. Normal is used becoz of direction (perpendicular to contact plane).

3. What does the "sigma" mean?

Sigma is a symbol that means sum of.

4. Is the net force not included the frictional force?

I can't understand your question here.

I have one little question of my own, how do u put all those formulas and symbols into your post ?

one thing about graphite is not it's hardness but it's "toughness"

along the x,y (in the graphene plane) graphite is very very strong

that's why members of our group make nano-sized graphite plates and blend them into polymers, if you have the platelets covalently bound to the epoxy resin, it increases the toughness (and Young's modulus, etc) quite a bit (and makes it black)

Not surprising considering the internal structure of graphite

Yes i have taken iq tests......how would they possibly give the same value each time ? It is not a deterministic value, there have to be slight variations, like in your case.

Because he's wrong

You need to use just 3% to reach this conclusion

I do not think such a law would be fair, especially since it is currently legal in sveral places.......There would definately be factions of people supporting it, otherwise it would not have been legal. Banning or controlling it now, would appear like curbing a sort of freedom of choice.

A mirage is formed due to refraction of light.

Refractive index depends on material density, which in case of air depends on temperature. On a hot day, a gradient of temperture is formed vertically in the air. In essence you can think it as layers of air with different density, as the coldest layer will be at the bottom (coldest => most density => most refractive index) , if u draw a geometrical ray diagram you will realise that light rays tend to become more horizontal. As a result, it apperas as if there is some water and you seem to see the reflection of objects in it (a mirage).

By the prnciple of reversibility of light, if you did shine a laser into it, you would see the laser at the back of the mirage, but you would need to have a screen or something. A powerful laser, should be able to show you the path of light rays thru the mirage as well.

The energy can't be removed without movement though - otherwise it would just sit there, so the movement gives energy, and warms it up again.

O.K. - so you invent something small enough to hold one atom still

that one atom loses all its energy

First of all, for trying to get close to absolute zero why even isolate a single atom, you can work with a bigger number than 1.

Energy transfer can take place through vaccuum without need of movement.

You do not need anything to hold the atom, it can be isolated in gaseous state using force fields.

Lastly, if you first go about studying the properties of matter without even defining the concept of temperature. Then when you start to define temperature, it will become obvious that there has to be an intrinsic lower bound to the value this property "temperature" can acquire.

Just curious........heard of this thing called a tsunami..........where does it stand in front of these 25 mt monsters ??

I see no reason to say reproductive cloning is bad........... the new individual may have the same DNA sequence and all but still would be a completely different individual with different behaviour and thinking.

i also belive double murder is a American thingy! Guess we donät have that here in sweden though..

Not sure about the double murder thing , but abortion is completely legal here in India, and foeticide is infact quite a common practice.

(What is illegal is trying to determine sex of the baby b4 birth)

The main reason for this legalised abortion is that religion(hinduism) does not oppose abortion.....I am not sure so I ask, does christianity oppose abortions ?

Getting back to the original issue, I would strongly feel against ending the life of even a diseased baby, becoz barring a few conditions there is always hope, and once the baby is born should it not be given a chance to live ?

You can end one's life but only by his/her own consent (euthanasia). This would just be murder. No matter how advanced medical science is, how can you trust it enough to tell you that the baby itself would be in suffering, and not just the people who are burdened to take care of it ?

I think that if you say that a retarded individual can be "put down", it is not you or a doctor who who has the right to decide that, and such steps should ONLY be taken if the individual, beyond all reasonable doubt ,is in perpetual pain or agony. This is where I must appreciate liberal societies like the Dutch who allow practices such as euthanasia (this wouldn't be much unlike euthanasia).

There is an ongoing debate over the ethics of human cloning and genetically engineering test tube babies. I see nothing wrong with either of these issues, especially because of the fact that genetically engineering test tube babies would ensure that such diseased and retarded foetuses would be rejected even before being injected into the whomb. Such a practice would certainly clear out some of the grey areas arising because of abortion.

I do not believe there are too many people who would consider case#1 as unethical, forcing the victim to have the baby would be more of a trauma.......

I feel that anyone who is going in for an early abortion would be very clear that she can't support a child or does not want one..... it is better not to have one in that case, rather than make a child feel un wanted or bring him up shabbily. This should always remai a choice of the person having the child, and taking this choice away would in my opinion be slightly unfair.

A would give the same argument for a late abortion, though many would argue that is out right killing a living being. I look at it this way, as long as the foetus is still a part of the mother, it is should be her right to decide its fate (I know many people would disagree with me here, but thats just the way I feel).

Now that you provided a link to explain partial birth abortion, it really does seem a wrong thing to do, because you first deliver the child and then just kill it. I am forced to change my opinion on this and must say this seems quite wrong thing to do.

The last three situations are just not the right thing to do, it is like clensing society.... What next putting down all those physically weaker ? Just not right........ you can't end a life like that. I must point out though that I am not against euthanasia, which would be a very diffrent situation from the three described here.

1) A 13 year old girl is raped and becomes pregnant. Would it be ethical to have an abortion early in the pregnancy?

 

2) Full age adult becomes pregnant. Would it be ethical to have an abortion early in the pregnancy?

 

3) Full age adult becomes pregnant. Would it be ethical to have an abortion late in the pregnancy?

 

4) Full age woman has a partial birth abortion

Ethical according to me (As long as no.4 means the same as no.3)

5) "Baby Doe" scenario. Potentially retarded born baby is refused life.

 

6) Normal born baby is "put down"

 

7) Retarded adult is "put down"

Definately not ok !

I have two :-

1) Gauss, because of the sheer number of brilliant results he proved

2) Schrodinger, because without his great equation we won't have the beauty of quantum mechanix

The only major countrys with the death penalty are China, the US and Japan. Although it's worth pointing out it's very rare in Japan and China is using it as a tool for human rights abuse.

I must add that here in India it is still prevelant. Why only last month a couple of people were sentenced.

what are you insinuating

Not insinuating anything......

Just trying to say that its a very well written book, exceptionally well in fact.

But at the same time, I must admit I don't consult to too many books so I havn't acctualy consulted it myself.

I think Edison made DC then Edison made elcetric chair part probably had led me to assume it was DC that the electric chair used , if I am wrong I apologise.......

is wattage really a word?

Well wattage as well as amperage are terms used a lot in practical situations, most people dealing with electrical devices tend to use these words.

Though this is deviating from the original post, I am sorry for that, but exactly what portion of Europe still enforces the death penalty ? and do all states in the US have the death penalty ?

I'll give you a brief historical build up leading to photons :

Upto the end of the 19th century (nearly) every phycist thought of light ot be a wave.

However it was about that time that people like Hertz came up with certain interesting experiments that involved phenomena of light which cannot be explained with the wave nature proposed at that time. The most famous of these is the photoelectric effect (look that experiment up on google, it is very famous). So, to explain photoelectric effect none other than Mr.Albert Einstein came up with an equation which you can derive only if you assume light to consist of a continous stream of small particls called photons.

The basic difference in the two approaches can be understood if you imagine light hitting a surface :

1) A wave would lead to a continous influx of energy on to that surface.

2) A particle nature (photons) would mean energy comes in a continous stream of small packets.

Though this seems quite irrelevant to a novice, but it is an extremely important concept and the essence of all modern theory on light.

By the way, it was acctually a gentleman by the name of Max Planck who had come up with this idea of energy being in the form of small packets in radiation around the year 1900.

Another way to look at it is to think of energy as you think of water, you see a photon picture merely means that the water itself is made of small "discrete" units (molecules), but still appears as a continous stream because of the shear number of molecules involved, exact same is the approach to photons.

Finally, light is now though to possess a dual nature which is necessary because some phenomena can only be explained if we think of it as a wave and others only if it were a particle. So depending on the situation, you have a choice wether to understand light's behaviour as particle or as wave.

THeres this famed noble prize acceptance speech (around the early years of the 20th century) of a physicist (i can't recollect who) who said something like

On Mondays, Tuesdays and Wednesdays we think of light as waves

On Thursdays, Fridays and Saturdays we think of it as a particle

And on Sundays we simply pray.

A better way to understand is too look at how the concept of temperature and how / why the absolute scale of temperature is defined and how it were initially though of (Courtesy Lord Kelvin).

The concept of heat and temperature only becomes clearer at an advanced stage of thermodynamics.

You can find this stuff in an any advanced book on thermodynamics and complete understanding generally requires a small amount of knowledge of quantum mechanix.

I am pretty sure we get HCl and HNO3 prepared as liquids and sold out to chemistry labs all over atleast here in India.

In fact in college, we now get HCl in bucket loads.

The physics book by Resnick and Halliday (I hope i spell their names correctly) is a real legend around here.

Its supposed to be simple enuf for a 9th grader to understand and have topics diverse enuf and given in enuf detail to keep you referring to it throughout your high school physics.

Most people I have known did not favour chemistry too much but it was my favourite subject throughout high school.

All the inorganic chemistry I ever did was just learning up loads of chemical reactions and properties but even that was fun, because of the diverse variety of inorganic chemicals.

Organic chemistry is a beautiful topic, which if taught in an organised manner is probably chemistry at its very best.

My experiences with physical chemistry off late have led me to repeatedly use calculus as an essential tool, so I don't appreciate it as much as the rest of chemistry, it becomes too mathematical beyond a certain point.