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  1. M

    Physics exam

    In which nation do you live?
  2. M

    The pen revolves

    Hi, Suppose that I am holding a pen in my hand and then i move my hand in such a way that the pen starts revolving around my index finger. It rotates in such a way that it seems that my finger is the center of the circular path(the path, through which the pen is revovling)...
  3. M

    Property of water

    Hi I know what surface tension is but is this the only reason for it
  4. M

    Property of water

    Hi When we fill a tumbler( of stainless steel) with water and then invert it ie empty it . The tumbler gets empty except a few drops of water. even if you keep the tumbler inverted for hours the water droplets do not fall down they remain stuck to the walls of the tumbler. I hope you...
  5. M

    What happens when a ray of light hits the boundary of the universe?

    Hi Please forgive me if i am wrong but i think this equation tells us that greater the displacement of an object in space coordinates the lesser its displacement in time coordinates eg: If an object moves at a velocity close to light than time will move slowly for that object.
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    What happens when a ray of light hits the boundary of the universe?

    When you talk about spacetime expansion, can you describe it more clearly:smile:
  7. M

    What is the Theory of Elasticity?

    Hi chris I am from India and i don't boast that i have understood everything but yes many of the parts you explained were very lucid and easy to understand.
  8. M

    What happens when a ray of light hits the boundary of the universe?

    Hi you are wrong for nothing exceeds the speed of light. You might be saying the above for the only reason that you might have a read an article saying that some experiments of NASA show that universe has expanded on all the sides by a great rate and they also think that the expansion of the...
  9. M

    Polarization of light

    With you I would like to know first of alll what is right handed circularly polarized light and left handed circularly polarized light ??
  10. M

    What happens when a ray of light hits the boundary of the universe?

    Hi As Hubble explained that when a balloon having dots is blown than the distance between the dots increase and it increases more for those dots which are relatively far from each other.Now the universe has no boundary it is not that you will come to an edge and than you will fall off. Also...
  11. M

    Photoelectric Effect and metals

    A short but clear explanation Hi The photons can only eject electrons when the frequency is greater than the work function. we know that the energy of the photon would be equal to hf. For eg if hf=phi than f is known as the threshold frequency here phi means the workfunction,now if hf>phi...
  12. M

    Movement of a shuttlecock

    Thank you all for the replies:smile:
  13. M

    Movement of a shuttlecock

    Hi Thankyou but then suppose that we have a single player and he just starts hitting the shuttle cock vertically in this case the shuttle cock travels vertical distance and then at the highest point it changes it behaves strangely ie in the beggining the cock faces us and and then it does...
  14. M

    What is the Theory of Elasticity?

    Chris If i was from the awards commission than i would have surely giveen you the physics guru award for 2007. A great post . I have just completed my 10th grade but still i can understand it cool:rolleyes:
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    Movement of a shuttlecock

    Quite a funny question Now when we hit a shuttle cock by racket or any other means, the shuttle cock moves in the direction of the force but halfway the position of the shuttlecock changes ie in the beggning the cock faces us and then at halfway the cock starts facing the opposite...
  16. M

    The double slit experiment

    Hi, We all know that when we shoot electrons one by one on an apparatus having two slits then it forms a interference pattern. Means this implies that the electron passes through both the slits at the same time Now when we keep a detector near the slits to watch the...
  17. M

    The Millennium problems

    Hi, Does anyone know about the Seven Millennium problems, if yes can anyone explain to me the yang mills theory, navier stokes equation and the poincare conjucture in great detail:smile:
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    Why the Photon?

    Welcome to the forums Now i don't know whether you are talking about topological manifold or a smooth manifold. But see photon is an elementary particle now the definition itself says that it is elementary. Now if we put your logic in physics than there would...
  19. M

    Two slit experiment - quantum theory - problem

    Welcome Hi i think that you must specify that whether there is a detector or not at any of the slits and whether the other slit is open or not.Other wise refer volume three of feynman lectures
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    Volume of Frozen water

    Sorry But your friend is correct.the ice cube floats ie a bit of it is outside water. Now definately the volume increases of the whole system but the amount by which the volume increases is exactly equal to the volume of ice outside water. now try to push the icecube in the water and...
  21. M

    Sun forms different geodesic

    Thanks pete.If i am not wrong than In general relativity, gravity is not a force but is instead a curved spacetime geometry where the source of curvature is the stress-energy tensor.Now than does it mean that if planets are swapped, as caesium said,for eg if Jupiter comes on Earth's place and...
  22. M

    Sun forms different geodesic

    Hi pervect I know that true geodesic motion is ideolised for test particles.But many a times we can consider it for real mass.I accept that due to this some discrepencies arise likethe real mass affects the background geometry.But here i would just like to know as why different planets...
  23. M

    Sun forms different geodesic

    I mean to say that.Earth moves on the geodesic formed by the sun's gravity.So along with Earth we also have different planets revolving the sun.So does it means that the sun forms different geodesics for different planets.because all the planets are not in a single orbit they are in different...
  24. M

    Sun forms different geodesic

    Hi, Earth follws a straight path in 4-d space the Earth moves over the geodesic formed by the sun's we also have other 7 planets.So does it mean that the sun forms different geodesic for differnt planets. if my question does make some logic than please explain me.
  25. M

    Question about Fusion

    Hii simple.The water absorbs the heat and so the plastic doesnot reach its ignition temperature.So it doesnot melt.Once the water gets emptied the plastic starts burnin/melting
  26. M

    Definition of candela

    Hi I cannot Understand properly the correct definition of candela.Can you please explain me.I know the definition by heart but i don't understand it properly
  27. M

    An excellent problem

    Now i would like to know that how it happens it is against common sense.
  28. M

    An excellent problem

    Hi pls read this its worth it.(assujme Earth as a complete sphere) suppose i stand in india(place where equator passes) right now and now i begin my journey with a rope thousnands of kilometers long i follow the journey exactly on equator and return to the same place in india.means...
  29. M

    Niels bohr model

    Hi, we know that we can find the radius and energy of the orbits of why is it so that we cannot apply the same formulas for other elements by using the equations given by bohr.if there are complications what are they?
  30. M

    What make the electrons to move in conductor with current?

    hi Hootenanny has explained very well.If you want a simpler explanation it follows To create a flow of any substance you have to develop a didfference between its two ends.whether it is a tube full of water or a conductor.when a potential difference develops at the two ends of a...
  31. M

    Dropping a tennis ball through the earth

    ha ha, sir your last comment has given me an another question to think about.why is gravity zero at the center
  32. M

    Dropping a tennis ball through the earth

    respectedsir, i am happy that you have contributed your time to my question.i am obviosly ignoring friction/air resisitance. but instead of torque let's think the other way out that when the ball reaches the center doesn't it stop there due to the gravity which is immense at the center
  33. M

    Dropping a tennis ball through the earth

    hi i am confused since many days about this problem which goes as follows suppose a tube that is longer than the diameter of the Earth is passed inside Earth such that its oother end comes right from the other side of the Earth and the tube passes through the center point of earth.that is...
  34. M

    Eading in many books that the unification of quantum mechanics

    hi i have been reading in many books that the unification of quantum mechanics and general relativity is not possible. but why? it is clear that we cannot use a certain theory for certain phenomen in the universe and other theory for the rest phenomenas of the world. at singularity we have...
  35. M

    Throwing a tennis ball through a wall

    hi, it is possible for the the ball to tunnel through the wall or the brick.but the probability of that to happen is 1 out of 10^34 times. so please don't try this at home.otherwise you will have to do this almost up to infinity. but these probability is only true if take the points into...
  36. M

    How to derive e=mc^2

    Hi, I am very eager to know how to derive e=mc^2. I am sure that you all would be knowing how to derive the world famous equation E=mc^2.i know the basics but still it is a tough job to explain that. But I am hoping that you would send me a reply as soon as possible. Thank you
  37. M

    Gravitational Acceleration

    hello The gravitational acceleration at the equator is the least and at the pole is the maximum due to the rotation of the Earth on its axis.Why?
  38. M

    Maths factorization problem

    Hello, I have got one mathematical problem and i am not able to solve it may i plese get some help. My sum is as foolws:- a^2+b^2=25 and a^3+b^3=91 so now find the values of a and b. Now here we cannot tahe into consideration that as a^2+b^2=25 , a=3 and b=4 or a=4 and b=3 .But we...
  39. M

    Solve math equation without assumptions

    One mathematical sum is harassing me since a few days the problem is;:- a^2+b^2=25 and a^3+b^3=91. find the value of a and b. Now here we cannot take that into consoderation that as a^2+b^2=25 , a=3 and b=4. But we have to find the answer without any assumtions.May i please get the...
  40. M

    Thermal expansion

    Hi, I want to ask one question about linear expansion. For eg if we take tke railway rails. then during summer due to the incresing heat the length of the rails increase. Now anything which has a mass has a volume so when the temperature of the metal rails increase during summer...
  41. M

    Quantum mechnics

    I don't know much about quantum physics but i know that, that we cannot predict a result of any action according to quantum mechanics but we can that there is a probability for every result Then for example,if i keep my hands ina way that my palms are touching the wall and if i...
  42. M

    Force carrying particles

    one simple but complicated question me is roaming in my mind since many days.We know about force carrying particles i.e gravitons,etc this particles carry force. but this particles are mass less and virtual then how can they carry force or energy?
  43. M


    hello, I may help you with your question.The speed of light in vacuum is 299792.458km per second and the distance between venus and sun is 108.2 million km From milind shyani(india)...