albertlee

I find something contradictory to these two questions and there answers.... 1) A breakdown truck tows a car of mass 1000kg along a level road, and accelerates 0.5m/s/s. What is the tension in the towline??? Ans: 1000/2 = 500N = the tension 2) A trailer of mass 1000kg is towed by means of a rope attached to a car moving at a steady speed along a level road. The tension in the rope is 400N, why is it not zero???? Any idea to the question in bold???? thx Albert

How do you call the topic/subject of transplanting an organ for an animal to another one??? For eg, transplant a human ear on a mouse??? Can any one give me an brief info about what is it used for, or, give a webpage as start, so I could later on search on this topic for myself?? thx Albert

In what condition, the reaction will be a dynamic equilibrium??? ie, there are are both back and forwards reaction taken place at the same time For ethnoic acid, we know it is weak acid, because the reaction taken place in the solution is not completely forwards, it has both back and forward, so is a dynamic equilibrium, but why it does not fully be forwards reaction, like HCl??? The second question reflects the questioning upon the 1st one Any body can help?? Oh, yes, according to my knowledge, for the formula of ethonoic acid, something like CHCOOH, the positive ion is H, and the anion is CHCOO, my chemistry teacher told me that positive ion starts first in a chemical formula long time ago, how come it is not something like HCHCOO??? Secondly, what is the difference between bases and alkalis?? thx Albert

thx a million to you guys!!! Eventually.....

thx so much for the explanation!!!

Sometimes I feel that many exercise questions, when describing the system, is quite unclear for eg, it just says the momentum of object A is x kgm/s, but not telling whether the internal forces are canceled out, or there is actually no force, like Newton's first law Albert

Just want to say, I feel "Algorithm + Data Structure" is the idea of art in porgramming Albert

how about control structure???? "Algorithm + Data structure" plays the elegance of programming, right??? By the way, what's so special about data structure??? Albert

thx so much but we all know that html file ends with *.html how about xhtml??? Albert

Well, I cannot understand your mathematical symbols..... Does it have to be that "hard"???

Newton's third law describes about force, what does have to do with conservation of momentum?? Secondly, in a system of conservation of momentum, there should be no external forces, but what internal forces??? Albert

thx for the explanation, I now know the difference between XML and HTML, but I am abit confused on the general difference between XHTML and HTML, so, probably can any one give an example of using XHTML which has a more significant advantage than using HTML??? thx Albert

Oh, thx you guys so much Now I realise that even the reference book can be wrong This what my reference states: By the way, so what is the idea of the full elegance those operators in full play?? thx for the responds Albert

yeah, Synapse's question wasn't fully defined.....

thx Tom, but what is the so-called "system" in this case??? If it helps, can any one provide an example in reality related to the law of consercation of momentum?? thx Albert

What does that explain??? When A exerts a force on B, B exerts an equaled magnitude force but in opposite direction What does explain the law of conservation of momentum??? Albert

I have trouble in understanding the difference between HTML, XHTML, and XML I think more possibly is because of my poor computer knowledge, so can any one explain the difference in detail in a plainer way??? thx Albert

In java, the order of pre/post increment operator comes first but why, for eg, int x = y++ the asignment operator executes first????, then y plus 1???? in my sense of logic, x should be y+1, not y according to the order of operator in java, y++ and ++y should be no difference, because they are the first in the order but actually, the JVM works not as what I expect, I think maybe the order of operator for java in my reference book is wrong, since x = y+1, that '+' should come before post increment operator in order as the result shows Can any one tell me how does the operator work in my particular case??? thx Albert Can any

Ok, can you explain the conservation of momentum plainer?? By the way, what is the similarity of conservation of momentum and conservation of energy?? as Atheist noted?? Albert

Oh... made a mistake that average velocity = v+u/2 not v-u/2 The law of conservation of energy states that energy can never be destroyed, it only transforms into different forms, how about the law of conservation of momentum?? thx Albert

so, swansont, you mean that when the collision takes place, even the momentum of cars is zero, will the passengers stay at rest as well?? Albert

and, Synapse, back to your question on whether there is an effect on the velocity of passenger by the mass of the cars or not, just consider the formula for the momentum p = mv if the velocity of the car is a constant, then the increase of car's mass will increase its momentum, so, it deduces that, when the car's mass increases, the passenger's momentum increases, hence, the passenger's velocity after the car collides increases, in your particular question Albert

Synapse, Let's assume each of the cars has a mass of x kg at the same velocity when they collide, their momentum will be 0, according to the laws of conservation of momentum now, both cars stay at rest Thinking back again, if 1 car has a momentum of y kgm/s, its passenger is also travelling at a momentum of y kgm/s, so the velocity of a passenger after the car collides is y / the mass of the passenger, and another passenger's velocity will be negative, ie, in opposite direction Albert

Well, I want to know the derivation of K.E. not change in K.E. Any way, how come I got different result for v2??? we all know that v = u + at t = d/[(v-u)/2] = 2d/(v-u) v = u + a[2d/(v-u)] = u + 2ad/(v-u) v2 - uv = vu - u2 + 2ad v2 = 2vu - u2 + 2ad Any help to the manipulation??? Secondly, I find it very helpful to see the relationship between momentum, force, and work in this way: momentum = kgm/s = Ns force = kgm/s2 = N work = kgm2/s2or kgm/s2(m) = Nm Ps. Tom, I cant understand your derivation, because I haven't learned calculus, or differential calculus or what ever it is, yet, Albert