Strings Definition and 548 Threads

Homework Statement One string of a certain musical instrument is 79.0cm long and has a mass of 8.79g . It is being played in a room where the speed of sound is 344m/s . A)To what tension must you adjust the string so that, when vibrating in its second overtone, it produces sound of...

I've watched a few documentaries about string theory, read about it, heard people talk about it. But I cannot visually grasp what the heck strings look like. Physicists (maybe not all of them but the ones I only hear) like to say stuff like that if you pluck a guitar string you get a certain...

I have an assignment for my CS class. It is the following: * * complete the function: * * timesFound(string searchIn, char searchFor); * * The function should return the number of times the * character searchFor appears in the string searchIn. * */ int timesFound(string...

Homework Statement In a rescue, the 72.0 police officer is suspended by two cables, as shown in the figure below. Homework Equations T = mgsin(48)? T2 = mgsin(35)? The Attempt at a Solution I used the above equations and it is not right. Me and my friend have been working on...

By definition, D(irichle)-branes are branes on which open strings end. Then how closed string theories IIA and IIB may contain D-branes? Or more precisely, why the branes appearing in closed string theories are still called D-branes?

Just like you can create the ilusion of superluminal motion by projecting a flashlight into a wall, some strings would be projected into tachyons. Has anyone heard or thought about that?

Homework Statement A string 44 cm long will break under a tension of 24 N. Two such strings are tied to a 670 gm rock, their ends 60 cm apart. The rock is spun between them. What is the maximum speed it can spin before the string breaks? (Using pythagorean theorem, you can determine the radius...

Hi all ! I am curious about the possibility of knotted strings. If we can accept the propagation of closed loop strings, then shouldn't we consider the possibility of knotted, closed loop strings ? I do not see - offhand - any reason why a closed string cannot be knotted. Think of a...

Anyon are particular 2 dimensionsional objects and so is the worldsheet critical superstrings. But given that those 2 are extemely fashionable nowadays, and they happen in this dimension, I am extremely surprised to find that anyone didn't try anyonic strings. That is, instead of supersymmetric...

Petr Horava attempts to start at this paper a small quantum gravity theory, like Loop Quantum Gravity, except that he, according to his words: http://arxiv.org/abs/0901.3775v1 "In analogy with Yang-Mills, we are motivated to look for a “small” theory of quantum gravity in 3+1 dimensions...

Why do strings only have one dimension (or maybe branes have 2 dimensions)? Why aren't oscillating volumes (like a cube) used?

Homework Statement Ok, i need to make a program that will search for a substring in a given string, and replace it with another one.The Attempt at a Solution #include<stdio.h> #include<iostream> #include<string.h> using namespace std;int fsubstitute(char *ulazni, char *prvi, char *drugi)...

Hi I know I have been asking many questions. It seems this stuff is a lot more difficult than I thought so: 1.) Is the Quantum Field the field responsible for the creation of forces and particles, if not what does it say in a nutshell. 2.) If there are parallel universes do they affect...

My question is simple and straight forward - how does a 1-dimensional string "convert" to a zero-dimensional point particle? And another one - for the purposes of physics, energy is not a physical object but an abstract mathematical construct. So how can a string of energy have a definite...

Homework Statement A 30-cm long string, with one end clamped and the other free to move transversely, is vibrating in its second harmonic. The wavelength of the constituent traveling waves is: A) 10 cm B) 30 cm C) 40 cm D) 60 cm E) 120 cm Homework Equations L =...

Hi there, Two strings, tension T, mass densities mu1 and mu2, are connected. Consider a traveling incident wave on the boundary. Show that the energy flux of the reflected wave and the transmitted wave equals the energy flux of the incident wave. (The energy flux of a wave, the energy...

Homework Statement Given that the ASCII character system has 128 possible characters how many 5 character strings are there with at least one occurence of the '@' symbol. Homework Equations The Attempt at a Solution So clearly which symbol we're using doesn't matter, and I see...

Homework Statement A 119 mass hangs from two string Calculate the tension in both strings. Let θ1 = 77.0° and θ2 = 26.0 degrees Homework Equations Fnet=ma The Attempt at a Solution This is the last question of my homework packet (so its the most challenging) and I have no clue how...

I am required to use getline() and sscanf() somewhere in my function to read standard input and store it into arrays. I have input like this: 10/10/08 12:00 A1:2.31:1:P 2B:1.98:2:g 2b:1.82:3:b the first line is the time, which i used strcpy to copy it to an array called time[] the...

This is a general question... Given a pulley system that consists of one pulley and 2 strings--each with a mass hanging from it. One mass is 3kg, the other is 4kg. In class we concluded that the tension on each string was equal--why?

A mass of 6 kg is hanging from a string, named string 3. The top of this string is connected to to other strings, string one which goes straight to the left to connect with a wall, and string two which connects to the ceiling making a 40 degree angle between the ceiling and the string. The...

[b]1. problem one 3.1 kg paint bucket is hangin by a massless cord from another 3.1 kg paint bucket, also hanging by a massless cord. if the buckets are at rest, what is the tension in each cord? If the two buckets are pulled upwards with an acceleration of 1.9 m/s^2 by the upper cord...

I have got a question i am having a lot of trouble with. The question is that three strings on unequal lengths are used to support a mass of 50g. All of these strings are used to support the weight. Two of these strings cannot be in the same plane as the other string. Determine the tension...

Homework Statement The 4.00kg block in the figure (Intro 1 figure) is attached to a vertical rod by means of two strings. When the system rotates about the axis of the rod, the strings are extended as shown in the diagram and the tension in the upper string is 82.0 N. Homework...

Hey Guys, I am currently reading Brian Greene's The Elegant Universe which introduces many of the basic ideas behind string theory. While reading it i am constantly reminded of the skepticism with which many people regard string theory and it makes me wonder whether the book is biased or...

Homework Statement A bird feeder of large mass is hung from a tree limb, as the drawing shows. A cord attached to the bottom of the feeder has been left dangling free. A child pulls on the dangling cord. The dangling cord is cut from the same source as the cord attached to the limb. Is the...

So, what are the theories' predictions which are going to be tested on LHC? And if they won't be found, Does it mean they will be refuted or not?

Homework Statement Three strings, in the horizontal plane, meet in a knot and are pulled with three forces such that the knot is held stationary. The tension in string 1 is T1 = 2.9 N. The angle between strings 1 and 2 is q12 = 130° and the angle between strings 1 and 3 is q13 = 120° with...

To prove that some function is limited we use |an|\leq K (n \in \mathbb{N}) where K = max { |m| , |M| } What this last part mean K = max { |m| , |M| } ? Thank you.

Is there any general formula for strings? For example: what is the formula of this string -1,3,-5,7,-9,...? Thanks.

mass m suspended by a pair of vertical ropes attached to the ceiling what are the rope tensions if they comprise a V shape each at an angle theta with the ceiling? i have played with this problem for a while and i can't seem to find what the relevant equations are really only first time...

I've just read in the first pages of The Elegant Universe that Greene believes that all fundamental laws should be contained in the microscopic domain, all other laws are derived. Is it really so evident that the laws of thermodynamics are derived and not fundamental? The second law, is it...

The fundamental part of string theory is that particles are in fact made up of vibrating strings. So this means that the lowest form of unit is a vibrating string? It goes like this Human - made up of atoms - atoms made up of subatoms (electrons, protons and neutrons)- quarks. And then...

Astronauts in space cannot weigh themselves by standing on a bathroom scale. Instead, they determine their mass by oscillating on a large spring. Suppose an astronaut attaches one end of a large spring to her belt and the other end to a hook on the wall of the space capsule. A fellow astronaut...

Consider this real situation: Light from a far-background galaxy is observed to be lensed by a closer massive galaxy. Individual photons that graze the closer galaxy travel to the observer along various geodesic paths, as prescibed by GR. Now consider a very hypothetical situation. Suppose a...

I posted link to the Strings 2008 speaker lineup at the Announcements sticky. We can do some digging and get prepared for what is to be expected. there are eight one-hour overview talks, and nearly 30 half-hour specialized research talks. All the talks are plenary--all in the same...

Say you have 2 masses connected by a massless string, and another massless string is connected to the rightmost mass. A tension force T acts along this rightmost string, resulting in the string connecting the 2 masses to become taunt. In these cases, you can treat the 2 masses as one mass...

My final exam is tuesday and I am having an extremely extremely hard time grasping arrays and strings. I just can't visualize how they work and I am stuck on how to get my printOwnedShares function to work properly in a project that will help me study for the final. This is what I have worked on...

Two masses are connected by a string and are hanging from the ceiling of an elevator like this: [string 1] | [4kg mass] | [string 2] | [6kg mass] Show the tension of each string in the following situations: i) Stationary ii) Moving up at 3m/s iii) Moving down at...

Homework Statement A 1.0kg ball is attached to a vertical rod by two strings. Each string is 1.0m long, and they are attached to the rod a distance of 1.0m apart. The rod-ball-strings setup is rotating about the axis of the rod. As it rotates the strings are taut and form an equilateral...

Could the string theory be interpreted as low-energy theory of elementary particles? As is known, the theory of strings has many interesting and important possibilities, but it cannot be verified because of the Planckian scale. Does arise the question: is it possible to construct the theory...

Could someone tell about the physical meaning of these SO(32) groups in superstring theory? I am under the impression that it is a symmetry of the quantum superstring, but that it is not a symmetry of any underlying classical model, is it? Because if it is so, it is very different of the GUT...

c++ strings help! Homework Statement Create a C++ program that would ask the user for a username and password. Password field should be masked. If the user exceeded three errors, a string will be seen on the screen which says “ERROR” and exits the program. username: ayen_lee...

Just a couple of Questions: for the wave function y(x,t) = A / (x-vt)^2+b ------> What is the importance of 'b' and what is its meaning? A Uniform Circular Hoop of string of mass m and radius r is rotating in the absence of gravity. Its tangential speed is Vo. Its length is...

Homework Statement Two wires are tied to the 360 g sphere shown in Figure CP7.61. The sphere revolves in a hori*zontal circle at a constant speed of 6.5 m/s. What is the tension in each of the wires? Homework Equations I can't figure how to find the tension. With so little given i dnt...

[SOLVED] Tension in Strings HELP thanks!--very simple. Homework Statement A 16 kg object hangs in equilibrium from a string with a total length of L=5m and a linear mass density of u= 0.0010 kg/m. The string is wrapped around two light, frictionless pulleys that are separated by a distance...

Homework Statement A rigid uniform horizontal bar of mass m1 = 85.00 kg and length L = 5.300 m is supported by two vertical massless strings. String A is attached at a distance d = 1.500 m from the left end of the bar and is connected to the top plate. String B is attached to the left end of...

Can someone please explain to me why string theories with open strings must also have closed strings? I've read it is due to conservation of energy, an open string not attached to a closed string will lose it's energy off an end. Does this mean all D-branes must be made from closed strings? I...

controversial new study indicates that there are traces of vast cosmic strings left over in radiation from the early universe. If indeed confirmed to be real, these cosmic strings would offer an unprecedented window into the extreme physics of origins of the universe. The idea is that snags...

Hey, what are the laws of vibrating strings? I can't find it in my college physics books! Help please!