mak10

energy isn't lost in totally elastic collisions. -mak10

air resistance is the friction force exerted on the motion of an object in air and increases with speed. upthrust is the upward force exerted on the motion of an object in a liquid, arises due to pressure differences and increases with depth. -mak10

http://www.turkishpress.com/news.asp?ID=33418

could you give me some good links where I can look this up in more detail?? and as far as I know, momentum transfer by photons (or gravitons) involves kinetic energy... which are, then, transferred to other photons. But where did that kinetic energy come from?? from other photons?? where did they get the energy from?? is energy, itself, composed of these photons (as i hear from womewhere, they were energy packets?) or the photons derive their energy from some source?? and it is this source, if it exists, that i am sooooo much interested in.... thanks! -mak10

coming back to the subject... does gravity possess some sort of energy source? it must, according to the fundamental laws of work and energy.... to create the centripetal force, even if the work done by the force tangentially on objects is zero. The idea of gravitons is just as hypothetical as tachyons... neither of them have experimental evidence, although gravitons are predicted by the string theory, which, itself, is in dire need for experimental evidence. But even if we assume gravitons to exist, I don't see how their existence compensates the need for an energy source. Gravitons are simply thought to transmit the attractive force of gravity, not act as a substitute for an energy source that creates the force. just my thoughts... -mak10

1. C = 87.5 therefore, H = 100-87.5 = 12.5 2. divide the percentages by their atomic masses... so C = 7.29 and H = 12.5 itself. 3. get the ratio of the two.. 7.29:12.5 = 1:1.7 = 1:2 (rounded off) 4. thus, empirical formula is CH2.... now get its molecular mass which is 12 + 2 = 14. 5. divide 56 by 14 = 4 = n 6. therefore, (CH2) x 4 = C4H8 <=== and you have the molecular formula. dont get too bogged down by the number of steps here... i just did it on purpose so you could understand every part of the calculation... its really simple once you get hold of the concept. just remember to get the empirical formula first by the usual calculations... then determine the value of n which is equal to the RMM of the given molecular formula divided by the RMM of the empirical formula you have found (it MUST be an integer!) and then simply do step 6. -mak10

oh well... guess my teacher was right. The problem was rather simple... the only difficulty I found was resolving g to find the acceleration up the ramp. But nonetheless... 210m too comes quite close to severian's value... so I think I can use either methods to get the answer. thanks for all your help guys! -mak10

that makes sense. find the vertical distance first and then using trig. to find the distance up the plane... you do get 159.1m . But get this... if you find the horizontal distance as well by u*cos60*t and use pythagoroas theorem... you get a different answer... 210m. now, I am really confused!

Imagine a projectile being launched up a frictionless plane inclined at 60 degrees to the horizontal.... with a velocity of 60 m/s. How can you use this two data given to determine the distance travelled by the particle up the plane and the time taken for it do that?? I was quite confused by this since i get differing answers to distance using different methods. If I find t by t=u*sin 60/g... and plug the t value in s=u*sin 60*t - 1/2*9.8*t^2.... I get the distance as 137m. But my teacher uses the equation v^2 = u^2 - 2*9.8*sin 60*s taking v=0 and gets the distance as 212m. So in a nutshell, I am stuck... I got my exams tomorrow... so if any1 could solve this out for me... will be greatly appreciated. Am I right or is my teacher correct or none of us?? -mak10

Does this also mean the gravitational force exerted by the earth on us and the moon is also caused by this distortion of space-time as a result of the relatively bigger mass of the earth?? -mak10

can I have some authoritative links where I can read about these?? thanks! -mak10

once again... the unit of acceleration is meters/seconds^2... and since 1N is equal to the product of 1kg and 1 m/s^2 ..... newton = kg m/s^2. -mak10

has this been experimentally verified? -mak10

interesting... but what is the source of this force?? And don't you require a tremendous amount of energy to provide the force necessary to bind us to earth and keep the moon, which is thousands of kms away, in orbit?? Anything that exerts a force must obtain energy from somewhere to do so.... it can't out of thin air. I wish I could ask my physics teacher about this but our periods are extremely limited and she doesnt give the full blown explanation that I need, so something remains lingered to my mind, that I spew in here . And she was explaning about something called gravitons that I ahvent the slightest clue of but it didnt answer my question though. -mak10

The only kind of fear, we Muslims were taught was to fear God and Him alone. Adding 'Islamic' before terrorists is not going to make them any more islamic than making republicans 'honest' or britney spears, 'modest'. And to say that the Quran basically talks of hellfire and painful doom is like saying special relativity only talks about mass increase. I would suggest you read the book first before judging it.... ~60% of the Quran talks about righteousness, respect, morality, worship, committments, belief and reason. I could quote many verses to support these, if you want... and this can be done in pms, since I dont want to turn this thread into a religious riot. just wanted to clarify the matter... please dont generalize all Muslims and put them in the same pot. There is a very good majority of the Muslims (like me) who loathe terrorists and condemn their actions... regardless of their motives. Killing innocent people is wrong is wrong is wrong.... and I am quite sure that apart from the Quran, the Bible and Torah also agree with this. -mak10

I will admit, time-travel is one concept that I have trouble understanding. If you encircle the earth 6 or 7 times per second... you have merely crossed the circumference of the earth 7 times in 1 second... how, on earth, then, does it affect your body's biology... like stop you from aging and stuff?? I also profess ignorance about einstein's relativity theories which maybe related to time-travel and all that stuff! My argument is that 1 second travelling at light speed is still 1 sec anywhere else in the universe... the time interval remains the same. Its just the distance you have covered in that 1 sec as a result of your speed that differs from the distance the snail has covered on earth for the same time interval. This is as how I see it.... but then again, i might be thinking solely in terms of newtonian mechanics, to what I have been taught as of yet.... but I would appreciate a good explanation of this phenomenon. Thanks! -mak10

I learned from my physics class that it is the strong gravity of earth that not only binds us to it but also keeps the moon in orbit... in a similar fashion that the sun by its extremely strong gravity keeps all the rest of the planets (that we know of) in orbit. Ofcourse, centripetal forces are also involved here but what I wanted to know is the energy source for this gravity.. more specifically, the source of energy of earth's gravity. Is it located at the central core of the earth, as some would predict?? what does it look like?? at what rate is the energy being used up (the power, i.e) and, if it goes at this rate, at approx. what point in time will it be totally depleted... as with the case with all region-specific energies?? Also, I have another question... also somewhat related. It is said that two masses always possess a force field between each other... and the larger the masses... the more stronger is the force firled, and more stronger the attration. I dont remeber the equation for this but its something like F = Gm1m2/4*pi*e0*r^2 (this is entirely from memory, so am not sure if its right).... e0 = absolon zero and r = radius, or more practically, the distance between the two objects m1 and m2 and G is some gravitational constant value that i dont remember at the moment. The main point of the equation is that the attract force between two masses is directly propertional to the size of the masses and inversely prop. to the square of their distance. So my question is... if this is true, howcome the bigger planets like jupiter and saturn are much more distant from our huge sun than the smaller planets like mercury and earth... which are much smaller in comparison?? shouldn't the attractive force make them more closer to the sun than the other small planets?? or is the effect compensated by the large distance between them?? Thanks and apologies for the long-winded post! -mak10

what about tachyons? heard their slowest speed, itself, is the speed of light!! so they do violate causality and special relativity, don't they? just curious... -mak10

the velocity of the ball, relative to the train, will be zero (as they cancel out) but its speed is still 70 mph... so no, it wouldn't 'stop'.... atleast, thats how I interpret it -mak10

http://www.chemguide.co.uk/atoms/bonding/electroneg.html -mak10

thanks for your comments VendingMenace. Well, the syllabus tells us to learn only about about cis-trans in alkenes that are caused as a result of the restricted rotation about the double bonds.... the teachers teaches us about the simple cis-trans configs and naming them.... even the question that appeared asks us to draw a cis-trans molecule of geraniol. Given all these factors, all of a sudden you face the problem of identifying similiar groups around the double bond of geraniol (due to the simple fact that there arent any!) and asked to draw cis-trans without having a slightest clue about E-Z systems!! I am sure you would be very tense.. I know I was! neeeways.... I'll just lose 3 or 5 marks, although I was aiming for 100%.... and here I am, still feeling all guilty for not knowing this. Oh well... thanks for all your help everyone, appreciate it! -mak10

this is possible in a complete vacuum. say, come to think of it... are perpetual motion machines not possible in outer space?? -mak10

velocity steadily increasing = constant acceleration = constant force velocity constant = zero acceleration = zero force -mak10

Ok, I think I figured this out. According to the IUPAC website given by the VendingMenance (for which I am really grateful to him!), So blike was right... when you have four different constituents on either sides of the double bond, the configuration switches from cis-trans to E-Z.... which I think is based more on the positions of higher priority ligands determined by their atomic numbers. I did a google search on E-Z and fortunately, there is a very good website dealing with it: http://www.geocities.com/Athens/Thebes/5118/obc/ez.htm It, surprisingly, gives the very same example I gave to jdurg, i.e - ClFC=CBrI and classifies it as E- (opposite sides) or Z- (same side) which we can roughly interpret as either cis (same as Z) or trans (same as E). But nonetheless, this still is a whole new system of configuration that we hadn't been taught for AS-Levels and clearly not in our present 2004 syllabus. So my question now is this: 1) The molecule Geraniol (diagram provided on previous posts) appears to have four different ligands attached to it and thus cannot be classified by the simple methods of identifying cis-trans positions but requires the E-Z system to be classified, which can, then, be roughly interpreted as cis or trans. Am I correct in my deduction? 2) Is cambridge right in mentioning about simple cis-trans isomerism is their syllabus but giving us as an entirely different molecule that requires a diametrically different mode of classification?? Or is it obviously expected to know about E-Z when cis-trans isomerism is mentioned? Thanks! -mak10