String Definition and 1000 Threads

Homework Statement I keep getting the wrong answer for this question: A taut spring for which μ = 0.05 kg/m is under tension of 80.0N. How much power must be supplied to the string to generate sinusoidal waves at a frequency of 60Hz and an amplitude of 6cm? Homework Equations ω = 2∏f...

"Foundations of physics" Special Issue: Forty Years of String Theory http://www.springer.com/physics/history+&+philosophical+foundations+of+physics/journal/10701 If this has already been mentioned feel free to delete this post. Articles free through march, A Critical Look at Strings (Carlo...

Given an action for a 5-brance ##S=\int d^6x\left[\sqrt{-g}{1\over {4\partial_r a\partial^r a}}\partial_ma(x)F^{*mnl}F_{nlp}\partial^pa(x)+ \sqrt{-\det(g_{mn}+i\tilde F_{mn})}\right],## where ##x^m## ##(m=0,1...,5)## are local coordinates of the worldvolume...

Homework Statement problem 4.4 The question: http://ocw.mit.edu/courses/physics/8-03-physics-iii-vibrations-and-waves-fall-2004/assignments/ps4a.pdf The solution: http://ocw.mit.edu/courses/physics/8-03-physics-iii-vibrations-and-waves-fall-2004/assignments/sol4a.pdf...

Homework Statement A 4-kg rock is tied to the end of a string and twirled overhead, 1.6 m above the ground, in a 1.1-m radius, horizontal circle. The string is known to break if its tension reaches a value of 514 N. The rock it rotated faster and faster until the string breaks. How far...

Homework Statement Given the tension T and unit mass per length U of a string what is the speed of sound along the string Homework Equations The Attempt at a Solution I know how to find the propagation speed of a transverse wave on a string, is that the same as the speed of...

This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth (because the rope is attached to bases that are attached to the ground). Actually if the bases are attached to the ground, that should...

I'm trying to learn more about the physics of guitars. I followed through the derivation of the transverse wave equation and that makes sense, but it seems like several of the simplifying assumptions might not apply. There are a lot of approximations with small angles and small slopes. I...

I'm working on my physics lab and I'm confused by the equation that they provide. μ=\frac { 1 }{ { (2Lslope) }^{ 2 } } What exactly does slope represent here? Also, what is the typical linear mass density of a string? I'm getting 0.673 grams per meter. Is this right? Edit: Never mind about...

Homework Statement A gymnast of mass 59.0kg hangs from a vertical rope attached to the ceiling. You can ignore the weight of the rope and assume that the rope does not stretch. Use 9.81 m/s^2 for the value for the acceleration of gravity. Calculate the Tension, T, in the rope if the gymnast...

Problem Two small identical small spheres with mass m are hung from insulating threads of length L, as shown in the figure. Each sphere has the same charge q1 = q2 = q. The radius of each sphere is very small compared to the distance between them, so that they may be considered as point...

Calculate the tension in the cable connecting the two masses. Assume all surfaces are frictionless. FBD m1 = 5 kg θ1 = 60° m2 = 6 kg θ2 = 70° Equation 1 ~ FT - Fg = ma FT - mgSinθ = ma FT = 5a + 5(9.8)Sin60 FT = 5a + 42.44 Equation 2 ~ Fg - FT = ma...

I have been following Dr. Michio Kaku and his ideas on string theory. My question is, with the addition of other dimensions, what types of experiments and/or results could possibly provide evidence that this theory is correct. If we currently can't perceive these "discrete" dimensions, what...

A string with a density/length of rho and tension T has an elastic spring with stiffness k at x=0. There is a step pulse (fi = H(t)) incident on this discontinuity. Determine the reflected and transmitted waves. Im not sure what boundary condition to use at the location of the spring. All...

Homework Statement Homework Equations Energy The Attempt at a Solution So I'm not exactly sure what this question even wants considering the statement is true by the work - energy theorem. Does it want me to show it explicitly for this case? If so, then, since there are no forces...

Homework Statement See: http://www.aapt.org/physicsteam/2010/upload/2010_FmaSolutions.pdf Question 11Homework Equations T_net = 0 F_net = 0 The Attempt at a Solution Start with F_net = 0: Let T1 be the force of tension on the left, T2 on the right T1cosθ=T2cosθ Y components: T1sinθ+T2sinθ = mg...

Don't know if it is a homework question or not but it was a friend asking me and I feel ashamed because I am engineer but I don't know. When whirling a supplied mass on a string in a horizontal circle with constant speed. Assume that the mass of the string is negligible compared to the mass...

Hello! I couldn't find any answer to a wondering I have: On one end of a light string, attach a heavy ball, and on the other end of the string hold it with your hand and whirl around the ball-on-string. You reach a high rotational speed and finally the string breaks at the string-ball...

Homework Statement This isn't actually a homework problem it's a problem I'm having in research since the fortran code I was given spat out a huge chunk of numbers. I've gotten the new-lines removed and I would like to graph what I have but it should really be organized in like 8-tuples. I...

Homework Statement A wave travels along a spring at speed v0. What will be the speed if the string is replaced by one made of the same material and under the same tension but having twice the radius. Answer in book says (v0/2) Homework Equations v=√(T/μ) speed= square root of...

From whst I have read, anything smaller than Plancks length, you need to account for quantum gravity.. also, it is assumed strings in string theory are Plancks length.. so how could anything be smaller than Plancks length if strings are Plancks length(or greater than)? I thought strings made...

Homework Statement Two uniformly charged spheres are suspended by strings of length L from vertically adjustable supports. The spheres are in static equilibrium. The angles with respect to the vertical are Q=14.9°, and T=20.7°. The tension in the string supporting sphere Z (Z with respect to...

Background-independence is the requirement that the theory be formulated based only on a bare differentiable manifold but not on any prior geometry. General relativity is the first example of such a theory. This is a radical shift as all theories before General relativity had part of their...

I have a lab to find the relationship between the two. I know the relationship, but I have to be able to measure the force of tension in a guitar string, or calculate it WITHOUT using the frequency. Is there an equation to solve for string tension where is it set up like a guitar string that I...

Hi all, I've got a question about waves and standing waves on a string fixed at both ends. I understand why only certain discrete wavelengths / frequencies are allowed to generate standing waves on a string such as a guitar string. My question pertains to understand what happens when a guitar...

hello, I find both quantum mechanics and string theory to be a bit iffy. Mabey it's just because I don't understand it but I think the best way to understand the iffy stuff is to post it on here. Mentors might see this as a debate or going against mainstream physics but how are you able to make...

Can Someone Explain What String Theory Is? (Simple Terms With Examples) Ive been hearing a lot of references to this new string theory, what is it?

Homework Statement A string 40.0cm long of mass 8.50g is fixed at both ends and is under a tension of 425N. When the string is vibrating in its third overtone, you observe that it causes a nearby pipe, open at both ends, to resonate in its third harmonic. The speed of sound is 344m/s. a) How...

Is it true that strings can vibrate in certain manners in which they cause a "ripple effect" in spacetime, affecting the topology of the higher dimensions, causing these different timelines to occur in which you have changes so minor as to electrons a plank's unit to the right, or so drastic as...

I'm trying to put together a little physics project, and I've constructed a rudimentary stringed instrument using a 2-liter bottle and some string. The string is fed through the bottom of the bottle and wound around a small dowel at the top end, and a small hole has been cut near middle of the...

There was a thread about how to describe the proton in string theory that was deleted while I was writing an answer, so I will post my answer here in a new thread. How the proton, and processes inside the proton, are described in string theory, is an open research question, part of the area...

Homework Statement In ”almost inertial” coordinates the energy momentum tensor of a straight cosmic string aligned along the z-axis is T_{\mu\nu} = \mu\delta(x)\delta(y)diag(1,0,0,-1) where μ is a small positive constant. Look for a time-independent solution of the linearized Einstein...

Homework Statement What is the tension of a string between 2 blocks of equal mass that are moving due to a pull of 17 Newtons?http://postimage.org/image/pmoibsy4p/ A. 8.5 B. 0 C. 17 D. 25 Homework Equations F=ma The Attempt at a Solution 17

Hey guys, who can tell me briefly about the 10+1 dimensions in the string theory? I am going to deliver a short presentation on string theory ,but i am not very clear about the reason that we have to introduce 11dimendion to string theory ...

Not sure what's going one, as soon as I remove the line with String[] arraySuit... all errors go away. With that statement in I get errors on several lines. Cannot figure out what's wrong. /* * Semester Project * Blackjack Class */ package project; import java.util.*; /** *...

This isn't actually a homework or coursework problem, but the style of the question is similar so I'm posting it here. Anyways, here goes. Consider a string of length L clamped at both ends, with one end at x=0 and the other at x=L. The displacement of the oscillating string can be described by...

string endpoints move at light speed--? In Zweibach's introduction to string theory I encounter the assertion that the endpoints of an open string move at the speed of light. A few other sources on the web agree with this. But nobody bothers to tell me what the heck it means (not even in...

I want to know if wave length or frequency will change when a wave move from a string of a certain linear density to another of a different linear density?

Homework Statement This is a communication question, no variables given: Predict what happens to the wavelength of a wave on a string when the frequency is doubled. Assume that the tension in the string remains the same. Confirm your prediction mathematically. The Attempt at a...

I just recently seen an article that the recent findings at the LHC seem to disprove supersymmetry. I would like to know how supersymmetry and string theory are connected and what the implications would be if the LHC totally disproves supersymmetry all together?

Here is a tricky one (for me) that uses linear mass density and two masses. I don't really know which to do so I did both! Homework Statement An object can be hung from a string (with linear mass density μ=0.00200kg/m) that passes over a light pulley. The string is connected to a...

A review paper by Bobby Samir Acharya, Gordon Kane and Piyush Kumar http://arxiv.org/pdf/1204.2795v1.pdf 12 April 2012 This is my first post here in a long time. I learned of this paper from yesterday's Lubos Motl blog. It is the most instructive string theory paper I have ever read...

Homework Statement I have a question pertaining to the simple harmonic motion of the midpoint of a guitar string with a frequency of 4.40 x 10^2 Hz and an amplitude of 1.60 mm. I've been asked to deduce the initial displacement, velocity and acceleration of the midpoint of the string, but am a...

Homework Statement A heavy wheel (radius = 0.3 meters, mass = 12 kg) has a rope spooled around it. A woman pulls on the rope from below with a constant force. She is able to bring the wheel from rest up to 1 radian per second in 10 seconds. [Ignore friction in the hub of the wheel.] a)...

Hello, I am a high school student trying to learn physics out of Kleppner and Kolenkow. Unfortunately, the solutions to some of the problems are not available online, nor is a solutions manual available, so I am unable to find out where I am wrong in some cases, such as this one. I would...

Homework Statement A small mass M attached to a string slides in a circle (Y) on a frictionless horizontal table, with the force F providing the necessary tension (see figure). The force is then decreased slowly and then maintained constant when M travels around in circle (X). The radius of...

Homework Statement Two bodies with masses m1 and m2 are connected by a massless thread that supports a maximum force |Ft|max . On mass m1 the force F1 = -β t x and on mass m2 the force F2 = 3 β t x (t: time, β: constant) acts. The motion is frictionless. Homework Equations When does...

Homework Statement A string of length L and mass m, hanging an object of mass M from the ceiling. After sending a transverse pulse from the top of the string , how much time we have to wait until the reflected pulse returned to the top? Homework Equations The time interval for a...

The string in the Figure is L = 120 cm long, has a ball attached to one end, and is fixed at its other end. The distance d to the fixed peg at point P is 75.0 cm. When the initially stationary ball is released with the string horizontal as shown, it will swing along the dashed arc. What is...

Homework Statement A tetherball with a string length of 1.5m is hit in such a way that it completes a circle around the pole with the string at 30 degrees from the pole. Assuming it doesn’t lose a significant length during the trip around the pole and hence takes a perfectly circular orbit...