Strings Definition and 523 Threads

Homework Statement Two marble spheres of masses 30 and 20 grams, respectively, are suspended from the ceiling by massless strings. The lighter sphere is pulled aside, as shown in the diagram, through an angle of 75° and let go. It swings and collides elastically with the other sphere at the...

I was reading the brief wikipedia entry on string and there it says that strings are one-dimensional "unlike an elementary particle which is zero-dimensional, or point-like. Quarks and electrons are thought to be made of strings." The part about zero-dimensional entities being made of...

Homework Statement Two identical point charges with a mass <i>m</i> and equal charge <i>q</i> repel each other at the end of a lightweight rope of length L=12.5cm. The angle θ is 17.5 degrees. a)What is the mass <i>m</i>? b)What is the charge <i>q</i>? Homework Equations Fx=...

Homework Statement Here is another question I had: http://desmond.imageshack.us/Himg84/scaled.php?server=84&filename=problem2v.jpg&res=landing The Attempt at a Solution I think the equation of motion for this system is: T- \ mg \cos 45 = I \frac{d^2 \theta}{dt^2} = I \frac{d \omega}{dt}...

I would like to build an electro magnet capable of causing piano strings to vibrate without the strings being struck first. As long as the hammers are up, the strings would vibrate on their own accord. An E-bow, used by guitarist for the same purpose, will (sort of) work on a limited range on...

I'm not sure if this question is something that has been asked before or if i thought about it myself or if it's completely ridiculous! But I was thinking, if, according to String Theory, particles are 1-dimensional strings that go through modes of oscillation, could they describe how a...

I know that cosmic string have intense energy and are apparently leftovers from the big bang and can create a sort of gravitational time distortion field, But HOW did these form from the Big Bang? Can their existence be backed up by other models?

In the thing I've read about string theory,nothing is mentioned about why do they vibrate. Can we tell one reason is uncertainty principle? And then interaction between them,changes patterns? Is there other reasons? thanks

Homework Statement Consider this string of digits: A=03161011511417191111 It has two 0s, twelve 1s, zero 2s, and so on. We construct another string of digits, called B, as follows: write the number of zeros in A, followed by the number of 1s, followed by the number of 2s, and so on...

Suppose you have 3 balls, all of equal mass, M. They are connected to each other by equal-length (each length L) strings of negligible mass, such that one ball is suspended in the middle and the two balls at the end are themselves suspended from the ceiling at two points, a distance X from one...

Homework Statement A uniform rod is supported by two strings. The string on the left hand side is horizontal. The string on the right hand side is at 30 degrees with respect to a straight line going from the end of the bar to the ceiling. If you had a straight line going from the end of the...

I believe in LQG where the theory itself regularises itself (quantised volumes)...string theory is supposed to account for infinities too cus the interaction is smeared over extended objects rather than point particles... First of all interactions don't occur at points in perturbative...

Homework Statement Create a function called isEqual(). isEqual() takes two strings and determines if the strings are identical. isEqual (s1, s2) should be the same as s1 = = s2 #include "stdafx.h" #include <iostream> using namespace std; bool isEqual(int *s, int *st, int x); int...

A stretched string of mass m, length L, and tension T is driven by two sources, one at each end. The sources both have the same frequency  and amplitude A, but are exactly 180 degrees out of phase with respect to one another. (Each end is an antinode). What is the smallest normal mode...

Homework Statement Two boxes, A & B are on a flat surface, and are connected by a massless string at an angle of 7° to the horizontal. Box A masses 9kg, box b 4kg. The boxes are pulled by a string connected to box A at an angle of 23° to the horizontal. Find the force required in order to...

Are there any theories as to what could possibly cause/create the vibrating one dimensional strings in string theory? Are the strings at the lower end of electromagnetic radiation? Or something completely different?

Problem: "One 2.80kg paint bucket is hanging by a massless cord from another 2.80kg paint bucket, also hanging by a massless cord" a. Calculate the tension in the upper cord when the two buckets are pulled upward with an acceleration of 1.54m/s^2 by the upper cord. T1 = upper cord's tension...

Particles actually "being" strings? I've heard that particles and the fabric of space can consist of many small strings, but then I heard that things like electrons are actually single 1-dimensional strings themselves...how could they have mass if they were just pure energy?

What is the probability that the stability of strings depends on prime quantities in order to be unique? Without prime numbers, would the strings break into composite states.

Hi ,I am doing some strings operation but it seems that compiler is doing extra copping. Can someone else verify this or is it my sloppy coding? Also I had to write std::cin ...etc otherwise compiler would like the code without that expression in main function. I am using Visual studio...

I am trying to understand why v = (T/mu)^(1/2) Equation 16.18 EDIT: T is tension, mu is the mass divided by the length of the string, v is the speed of the wave on the string. According to my book: "Let us use a mechanical analysis to derive Equation 16.18. Consider a pulse mov- ing...

Assuming strings are real, how many would fit in a drop of water? Perhaps this is a basic math question, or that the question itself does not make sense given the hypothetical and (currently) unobservable nature of strings. According to...

In string theory, what are the small strings physically made out of?

In string theory, what physically causes the small strings to vibrate?

If I need to write a c program which get a string from the stdin and prints it after a certain manipulation, the program is called that way: echo "Hello, World. bla bla bla" | program <arg> How can I save the string in my program before working on it? Thanks in advance

In this question, doesn't the string pull on both A (downwards) and B (upwards)? So wouldn't the spring be doubly compressed? Does it matter whether or not B is fixed? Also I don't understand the line: "The spring force is greater than the gravitataional force of A. Thus this spring will not...

1. A 50.0 cm, uniform, 57.0 N shelf is supported horizontally by two vertical wires attached to the sloping ceiling (the figure ). A very small 26.0 N tool is placed on the shelf midway between the points where the wires are attached to it...

Homework Statement If you were given the - linear density 1 = 2g/m - linear density 2 = 4g/, - total length of the strings = 4m - Length 1 > Length 2 - the fact that when a pulse is sent from a knot in the strings it reaches the ends at the same time How would you go about working...

Hello again! Homework Statement You are designing a two-string instrument with metal strings 35.0 cm long. Both strings are under the same tension. String S_{}1 has a mass of 8.00 g and produces the note middle C (frequency 262 Hz) in its fundamental mode. (a) What should be the tension in...

http://en.wikipedia.org/wiki/D-brane says, "The equations of motion of string theory require that the endpoints of an open string (a string with endpoints) satisfy one of two types of boundary conditions: The Neumann boundary condition, corresponding to free endpoints moving through spacetime at...

Homework Statement A mass of 17kg is supported statically by two strings. T2 has a magnitude of 150N at β=45° to the right of the vertical. (a)Calculate the vector T1. (b) If T2 was acting vertically downwards with the same magnitude as in (a) calculate T1. Homework Equations...

Homework Statement Write a program that takes a positive integer N and a string as command line arguments (N is assumed to be smaller than the length of the string). The program should pick N random characters from the string and construct and print a new string composed of these random...

Homework Statement 3 carts are connected by strings. The first cart is 5kg, the second 2kg, and the third 8kg. A string is fixed at the front of the first cart is pulled with a force of 30 N. In the following problems be sure to illustrate your answers with the corresponding free body...

I just wanted to double check my logic on something! If two masses are held vertically by two strings like so: [ceiling] [string #1] [mass #1] [string #2] [mass #2] ...then what forces are acting on mass #1? My free body diagrams are below, could someone double check if they're correct...

This goes for the people of loop quantum gravity and string theory. Think that you want to convince a very smart student of going into your field (strings or loops). How would you convince him ?? But, by doing it on a 5 lines paragraph talking about your theory and a 5 lines paragraph talking...

Homework Statement Three blocks on a frictionless surface are connected by strings like so (from left to right): Block 1 (m=10kg) to string with Tension 1 to Block 2 (m=20kg) to string with Tension 2 to Block 3 (m=30kg) to string with Tension 3. The blocks are pulled to the right with...

Hi all, I'm very curious about the current attempts to discover a theory of everything, and therefore naturally trying to understand better what string theory is about. One thing I don't understand is why anyone would use the label of 'strings' when we don't yet know what the theory will...

Has anyone here read Quantum Fields and Strings: A Course for Mathematicians vol 1 and/or vol 2? I was thinking about trying to tackle them but I'm unsure of what the mathematical prerequisites for doing so are. My background is in physics, but I have taken courses on differential geometry...

Homework Statement Two marble spheres of masses 30 and 20 grams, respectively, are suspended from the ceiling by massless strings. The lighter sphere is pulled aside, as shown in the diagram, through an angle of 75° and let go. It swings and collides elastically with the other sphere at the...

http://arxiv.org/abs/1108.0868 A critical look at strings Authors: Carlo Rovelli (Submitted on 3 Aug 2011) Abstract: This is an invited contribution to the Special Issue of "Foundations of Physics" titled "Forty Years Of String Theory: Reflecting On the Foundations". I have been asked to assess...

Hi, I have a question about the static gauge in string theory, in which one sets \tau = X^0 I understand that in the usual approach for strings in a flat target space, after the gauge fixing of the worldsheet metric gamma, \gamma_{\alpha\beta} = \eta_{\alpha\beta} one...

Homework Statement Three boxes are connected by strings of constant length. (A--B--C--> F) An applied force F acts horizontal in the positive x direction. mc=5kg, mb=2mc, ma=2mb. The coefficients of static and kinetic friction are 0.2 and 0.1 respectively and are the same for each box. The...

"String" in java.. Homework Statement its a bit conceptual question. there is a string class which we use to store strings of letters. 1) but we don't create a reference to it,nor we instantiate it. 2) not even a method is invoked mean in printing, we just mention name of string class. 3)...

Two strings which are fixed at both ends are identical except that one is 0.65 cm longer than the other. Waves on both of these string propagate with a speed of 34.9 m/sec and the fundamental frequency of the shorter string is 220 Hz. a) What is frequency of the beat that would result if...

How do we describe vibrating strinGs and branes? Is this connected with vibration of circular or quadratic membrane and PDE Helmholtz equation and how? How to test string theory in experiments?

I am trying to find out if my general understanding of the strings in string theory is correct. The strings can vibrate along different nodes to create the particles. Do the strings themselves ever wander around as a whole string, or would they be considered to be locked in place like pieces...

Hi, Can someone please tell me if current versions of string theory assume (or perhaps result in) a conservation of the number of strings in the universe? Just like conservation of matter and energy. If my lunch is made up of tiny vibrating strings, was it the same strings that existed...

Please forgive my lay understanding of String Theory, but when contemplating it, I am drawn to two questions; one at a level 'above' string theory and the other 'deeper'. I will begin with the former. As is my limited understanding, strings, according to restrictions placed upon them by the...

Hey everyone! If I have a function that takes a pointer to char (i.e. char array) as an argument, can I pass a "string literal" (I think that is the right term) as an argument to that function, even if that string hasn't previously been declared anywhere? For example: void myfunc(char...

All, I have a ListSurfacePlot3D graphic and wish to label the tick marks using strings. For example if I have X={x1,x2,x3} I would like to label each tick mark at that point with a string, i.e. x1="a", x2="b" etc. I would also like to know how to take a list of strings and distribute them...