String Definition and 1000 Threads

Homework Statement Two objects are made of identical material and are tied together with string. The first object has a mass of 5.0kg and the second object has a mass of 3.0kg. Students measure the maximum force of static friction as 31.4N to move both objects across a horizontal surface. a)...

Where can I learn string theory online with the math and everything? ANY help appreciated. Tanks in advance. Ps I'm looking for links, I really can't afford books. I'm a high school student. I know the principles but haven't attempted any math above the Schrödinger equation for a quantum...

My plot seems wrong so I am not sure what the problem is: (a) mistake in sol (b) mistake in coding. A clamped, uniform string under tension \(T\) has length \(\ell\). The string is struck in the middle, giving an initial tranverse velocity distribution \[...

Hey! So If I have a stretched string of length L fastened at one end, and I am moving the other end sinusoidally, will a standing wave appear ONLY if I move the other end with one of the normal-mode frequencies of the string? If not, will the resulting wave be a moving wave which is a...

So I have one attempt left and want to make sure my answer is correct, so double checking me would be super awesome! You are given a pendulum composed of a 0.030 kg mass on the end of a 0.42 m long massless string. The pendulum is moved 25° from the vertical and released. Find the tension in...

Just to clarify, if a string has a threshold of 100N, can the string be bent so that the tension in different parts individually doesn't exceed 100N yet the total force of the tensions do? My question arises because of this question: http://imgur.com/90NGY5p http://imgur.com/ObRq5QM...

I take it strings are too small to have "connectors" on their ends, there is no glue etc. so how could strings combine to become larger particles like bosons. I have never heard anyone describe the reason for the extra dimensions that string theory says are there. Could it be that these...

Hi there! S-matrix is Path Integral with Vertex Operators inserted. I know how to compute Shapiro-Virasoro amplitude. So I don't have problems with calculations but with understanding. In this calculations formalism of 2-dimensional CFT is used. But there is no S-matrix in CFT, only...

According to string theory there are an extra 7 spatial dimensions curled up at every point in space. They are so small(Planck length) that nothing can move through them and are completely undetectable. My question is this: Does string theory allow for these dimensions to uncurl and become...

Homework Statement A block of mass M has a string of mass m attached to it. A force F is applied to the string and it pulls the block up a frictionless plane inclined at angle θ to the horizontal. Find the force the string exerts on the block. Homework Equations F = ma The Attempt...

1. A violin string is 35 cm long between its fixed ends and has a mass of 2.0g. The string sounds the note A4 (440 Hz) when played. Homework Equations v=\sqrt{}F/ρ The Attempt at a Solution I calculated ρ, mass per unit length, to be .0057 kg/m but do not know how to find the...

Homework Statement http://home.phys.ntnu.no/brukdef/undervisning/tfy4145/ovinger/Ov03.pdf look at "oppgave 5". In the problem, you have a massless string with 4 uniform masses attached symmetrically, and you are supposed to show that the implicit equation for x (and x = cos(alpha)) is correct...

I would like to calculate the maximum distance, crest, a guitar string will travel at it's center when plucked in order to determine how high the string needs to be on the fretboard to avoid striking parallel frets and thus avoiding "fret buzz". Example: 0.762 mm string thickness with...

A 10g mass is suspended from a string and immersed in a beaker of liquid(Weight of beaker and liquid = 500g). A boy hold the string with his hand not letting the 10g mass touch the bottom of the beaker. (let upthrust generated by mass be X Newton.) Qn: what would be the reading on the...

Hey everybody, I have a few questions about membranes in string theory, so here it goes. What is meant by the membrane in the cyclic model, from my understanding it means that branes in an ultiverse collide, and create there own universes, would this mean that branes could collide in our...

Homework Statement The linear mass density in a string is given by μ = μ0[1 + cos(x/R)] where R is a constant. If one averages this density over the large size L it becomes uniform: <μ> = μ0, where <…> means averaging. What is the minimum size L (in terms of R) such that the density can be...

I thought about this when hanging my belt on to the towel holder. If i put too much of the belt on one side, that side would fall down. Why does this happen? Shouldn't the towel hanger just put up an equal force to the total weight of the belt keeping it up? I understand a little when we say...

The presence of a cosmic string does not lead to gravitational attraction of a particle placed some distance away from it. But it affects the geometry of planes orthogonal to the cosmic string, such that the circumference of a circle traced out when moving around it at a distance r is given by...

Homework Statement A solid uniform 45.0 kg ball of radius 0.16 m is supported against a vertical, frictionless wall using a thin 0.30 m wire of negligible mass. Find the tension in the wire. Homework Equations Sinθ = opposite/hypotenuse Cosθ = (m*g)/T or T/(m*g); I'm not...

Why is tension in a massless string same throughout its length?

Hi all! I am ready for applying for my PhD which I want to be on String Theory and in Europe. I am finishing my master's degree in Theoretical Physics and currently I am researching Holographic Renormalization for asymptotically non-AdS space-times. I am interested in all aspects of String...

Are the strings in M-Theory impermanent, do they decay for example?(I am not a physicist, curious from a philosophical perspective)

Why string field theory doesn't explane a black singularity but its called the theory of everything? It just explanes quantum gravity not why the universe exists or why we exist, what I am tring to say is that it should not be called the theory of everything.

... due to whatever. What has the effort provided besides showing that the universe doesn't work a certain way? Assuming it has aided in other areas of physics and mathematics. Any examples? Thanks.

I just can't get why for a massless inextensible string passing around a frictionless pulley we easily take T1=T2 (in fig.).My profs. never did explain this & jumped on further & when i ask them they won't answer saying it was very basic and other students say it's obvious. pls. help also pls...

1. If two books are tied together with string and one is pushed off the edge of a table. What the acceleration of the two books? Zero g/2 g a value between zero and g a value that could be greater than g 2. gravity acceleration laws 3. G, because gravity acceleration is independent of mass

Homework Statement Given that the stretched length of a string is Δx(1+1/2(dy/dx)^2) show that the potential energy per unit length is equal to 1/2F(dy(x,t)/dx)^2 Homework Equations potential energy = kx^2 cos(kx-wt) idk really... The Attempt at a Solution The fact that the...

This was just posted on arxiv. It seems to be of general interest so here's a thread in case anyone wants to discuss it. http://arxiv.org/abs/1308.1977 Holography without strings? Donald Marolf (Submitted on 8 Aug 2013) A defining feature of holographic dualities is that, along with the bulk...

what are the research prospect of doing a phd on string theory in India

Laurent Freidel is working on string theory again. His earlier paper, with Krasnov and Livine, which had a remark on the subject was Holomorphic Factorization for a Quantum Tetrahedron http://arxiv.org/abs/1307.7080 Born Reciprocity in String Theory and the Nature of Spacetime Laurent Freidel...

From looking at the Wikipedia entry on string theory I gather that it is found that any given physical model implies two Calabi-Yau spaces. Perhaps one space gives rise to a sector of particles with left-handed weak interactions and the other gives rise to a sector with right-handed weak...

Hi everyone, I was wondering what forces would counteract the force of gravity on an object which is spinning horizontally on a string. I realize its a component of the tension, but how does the force come about? Is this force also the reason that the object's plane of rotation rises when we...

Homework Statement Object A has mass 90.0 g and hangs from an insulated thread. When object B, which has a charge of +130 nC, is held nearby, A is attracted to it. In equilibrium, A hangs at an angle θ = 7.20° with respect to the vertical and is 5.00 cm to the left of B. (a) What is the charge...

Does the math in string theory tell us anything about the size of any of the extra dimensions?

Why does the string in an experiment setup fro friction experiment be parallel to the horizontal plane? What is its significance? (see picture attached)

The notion field of Quantum Field Theory is deduced from the combination of Quantum Mechanics and Special Relativity.The local characteristic of field is led from Cluster Decomposition Principle. String Theory is also a combination between Quantum Mechanics and Relativity Theory.Then I wonder...

In another thread Ben indicated that string theory formulated as non-linear sigma model using world-sheet action is - in some sense - background independent. To discuss this I start with a generalization of the Polyakov action ##S_G[X] = \frac{1}{4\pi\alpha}\int d^2\sigma \, \sqrt{g} \, g^{ab}...

There is still, to this day, absolutely no empirical proof that string theory is correct, or even that it can predict anything , but I know it's mathematically elegent ,here's feynman view on it:''I don’t like that they’re not calculating anything. I don’t like that they don’t check their ideas...

One of my goals in life is to get a reasonable understanding of string theory. This is done as a hobby of mine so I will not have a professor to ask. My question is: which route would you recommend for learning this? My thoughts: I understand many people think highly of "A First Course...

Hmm it seems that there is a Strings Sogang Channel in youtube but the videos are not public, so you must known the link for each. Here you have John Schwarz talk Or, if you are in hurry, just the transcript of the talk, via youtube ASR http://www.transcriptsearch.com.es/id/mMHyKm_i-1w

Homework Statement If you swing a ball in a vertical circle using a thin string, at the bottom of the circle the tension in the string must be greater than the ball's weight. True or false? Homework Equations F = mvv/r F = mg The Attempt at a Solution The correct answer, it says...

Hi. I've been working on a project of angle stabilization for a vehicle moving along a string, looking like this: The propulsion system is connected to the central wheel, while the outer two wheels are used for support. I've observed that during acceleration the vehicle rotates. I...

I was recently given the challenge to take a string of numbers (ages) and + x - / to equal another number (age). As part of the challenge each number can only be used once and you must only use numbers here to do multiply, add to, subtract from or divide by. NUMBERS 7 9 11 37 45 45 47 75...

Two charged objects of charge q. Coulomb's law states that the force on one sphere by the field of the other is: F = qE But each sphere experiences that, correct? So the tension for the string would be 2F. Is that correct?

Hey everyone, I've been trying to get a rough idea of what types of classes I should be taking for my upper level undergrad courses, and get an early idea of what type of graduate elective courses I should be taking. I'm a double major in physics and math, and plan to go to grad school for...

"This figure is a snapshot graph of the instantaneous velocity of the particles on a string. The wave is moving to the left at 50 cm/s. Draw a snapshot graph of the string's displacement at this instant of time." So it seems to be a quite basic question, where it's pretty much just an...

Hi As far as I understand, that teleportation using quantum entanglement is only partially instantaneous, because a classical channel has to be used to send the two qbits from Point A to B. So the speed of light is the boundary as how fast teleportation can happen one day using this...

Homework Statement A hollow steel sphere of inner radius 0.9m and outer radius 1m is submeged 1000m below the surface of the sea. Take the density of water to be 1000 kg/m^3 and the density of steel to be 7.8 x 10^3. Calculate the tension in the wire to support the submerged sphere...

Hello, I don't understand how changing the amplitude does not change the period but changing the length of the string does. Each changes the height and changes the arc length so wouldn't they both change the period? Thank you for any help!

Hey, It's been a while since I've dealt with the 'Weight' concept, if we have a string with N molecules and 'n' of the N molecules are in an excited state and the rest (N-n) molecules are in a ground state - what is the weight of this system? Any help would be appreciated, SK