String Definition and 1000 Threads

Homework Statement The figure below shows a snapshot of a standing wave on a composite string. It is a node in the composite point. If the aluminium string has a diameter of 1.50 mm, which diameter does the steel string have ...

We have had a heated debate at work and I feel we need to bring in a few outsiders into help clear things up. A co-worker of mine believes that if you had a string of bucky balls (small spherical neodymium magnets) held by only the top ball in the chain and allowed to hang such that you could...

Definition/Summary Take the case of a string with it's one end [which will refer to as the 'fixed end'] tied to a wall. The other end [which we will refer to as the 'free end'] is held by you. It is a common experience that if we move that free end, a 'bump' travels along the string. And if...

Hi all! I am currently conducting an investigation into the way in which frequency varies when you change the tension on a guitar string. I am aware of Mersenne's laws, and that frequency should vary in square root proportion to tension. I'm looking for an explanation that goes beyond simply...

Homework Statement Let S bet the set of all string's of 0's and 1's. define D: S --> Z as follows : for all s in S, D(s) = the numbers of 1's in s minus the number of 0's in s. a) Is D 1-1? Prove or give counterexample b) Is D onto? Prove or give counter example Homework Equations...

Homework Statement Hey everyone, I have a question regarding file IO in java. My assignment says: Extend program 2-add menu items Open(reads employees from a file),Save(writes employees to a file already specified), and Save As(writes employees to a new or different file than the one...

Question: Two pulleys of masses 12 kg and 8 kg are connected by a fine string hanging over a fixed pulley as shown. Over the 8 kg pulley is hung a fine string with masses 4 kg and M. Over the 12 kg pulley is hung another fine string with masses 3 kg and 6 kg. Calculate M so that the string over...

Homework Statement A uniform chain of length L hangs from an elastic string of natural length L. The upper end of the string is connected with the ceiling .When the system is in equilibrium , the string stretches by an amount L .At what distance from the lower end of the chain ,the chain...

Hi, if you remember back a decade ago we had a discussion on solutions to the first edition of Zwiebach's undergraduate textbook in string theory. (I have a copy of the solutions in my computer). Does someone have solutions to the updated second edition of the textbook? I tried looking for...

Can string theory explain dark matter and dark energy?

Homework Statement my question is on part b Homework Equations The Attempt at a Solution the period will be shorter due to smaller mass of oscillating system... but the amplitude is greater( ans from my book , in my opinion, the amplitude should be smaller because the string is...

Homework Statement the answer is a for this question. but i don't understand how to get the solution. Homework Equations The Attempt at a Solution mg-k(l-a+b)=ma since mg=k(l-a) -kb=ma a=-(k/m)b k/m=a/b so my ans is sqrt root( a/b)

Homework Statement The length of a stretched string is 1m. Its mass per length is 2x10-3kg/m. The string resonates at its 4th harmonic at 400Hz. (a) Calculate the velocity of the string wave. (b) Calculate the string tension. Homework Equations fn = nv / 2L v² = F / μ The...

Homework Statement A mass of 3.50 kg is suspended from a 1.59 m long string. It revolves in a horizontal circle as shown in the figure. The tangential speed of the mass is 2.99 m/s. Calculate the angle between the string and the vertical. Homework Equations a_c = v^2/r F = m*a_c...

What are you thoughts about Laura Mersini Haughton´s theory of the multiverse? She predicted a CMB cold spot, power suppression at low multipoles, preferred direction associated with the quadrupole octupole alignment, dark flow, and the deviation of the CMB amplitude. While dark flow remains...

I have been given a project in my ap physics class where I am to explain how Bose-Fermi equivalence, tachyon, dilaton, green-schwarz anomaly cancellation and kahler manifolds relate with string theory. After an hour of research, I realized that I could not find even the slightest information on...

Homework Statement A light string is wrapped around a solid cylinder and a 300g mass hangs from the free end of the string. when released, the mass falls a distance of 54cm in 3.0s. a) Calculate the tension in the string. b) Calculate the mass of the cylinder. Homework Equations...

Hello, Is string theory or M theory wrong ? Isn't it the theory of everything ? Should we continue our research to reach the true theory of everything ? If so, why physicists still research on string theory ?!

through the string? I'm at a point in a program I'm making where I have a string representation of a valid decimal representation of a double. By "valid representation" I mean that it contains only characters in the set {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.'} with no more...

Homework Statement a 4-kg block is attached to a string 2 m in length rotates on a horizontal surface. (a) If the co-efficient of friction between the block and the surface is .25, find the work done by the force of friction in each revolution of the block. Homework Equations Wnc=...

I am looking for literature on a certain topic in mathematics inspired by string theory of which I have heard bits and pieces. Since I am not at all familiar with string theory and haven't found anything online, I was hoping someone more knowledgeable might recognize some of the keywords I...

Are there any solutions (ways to avoid/get rid of) to the string theory landscape besides the anthropic principle and comological natural selection?

a wave pulse on a string has the dimension shown in figure (see attachment) the wave speed is v=1 cm/s. point o is a free end, the shape of wave at time t=3s is? someone please explain why would the answer to this question differernt if the point O was a fixed end? how does it make a difference...

Anything that exists has to exist/interact with at least 4 dimensions, right? Stuff existing/interacting with other dimensions too (even if they can't be/haven't been observed) have to exist/interact with our 4D as well, right?

Homework Statement See attachment (stuck with part b at the moment)Homework Equations The Attempt at a Solution \phi=D(x)T(t) so (1+bx)D''(x)T(t)-D(x)T''(t)=0 (1+bx)\frac{D''(x)}{D(x)}=\frac{T''(t)}{T(t)} let \frac{T''}{T}=\sigma (1) use trial solution T=be^{rt} subbing into (1) and solve...

Hello. I'm learning about high power LED's. I would like to design a high power LED driver for a DIY project I'm working on. I'm planning on using an LED driver to provide constant current and have dimming control through PWM. I'm going to be using 3W high power LED's in a series configuration...

Hello everybody. I have a BSc in physics, I tried hardly recent two years to get high scores in GRE/TOEFL exams to get accepted in U.S. and continue my education in physics,however, I rejected badly. First I thought by myself to leave physics, I gambled whole my future for physics and now I'm...

How does where you pluck a guitar string affect the pitch of the note? Does it or does it not? Can you explain this in terms of harmonics? Does where you pluck it simply change the harmonic content and not the frequency? Thanks. Also how is resonance and standing waves on a string and...

Homework Statement A light elastic string on a smooth horizontal table has one of its ends fastened. The other end is attached to a particle of mass m. The string of force constant ##k## is stretched to twice its natural length of ##l_0## and the particle is projected along the table at right...

Homework Statement Uniform rod AB with end B resting against rough vertical wall. Coefficient of friction between wall and rod is μ. Rod is 2m long and has mass 3kg. Rod is kept in limiting equilibrium by a light inextensible string, one end of which is attached to the end A of the rod and...

Homework Statement A yo-yo of mass M is composed of two disks of radius R separated by a shaft of radius r. A massless string is would on the shaft, and the loose end is held in the hand. Upon release the yo-yo descends until the string is unwound. The string the begins to rewind, and the...

I am trying to understand the connection between eternal inflation and the the string theory landscape of 10^520 possible universes Where is the original scientific article that proposed so many false vacua solutions If anyone can point me to the underlying equation and article that...

Hi, if I have a mass on a string and I swing it around my head at a constant speed, what is the resultant force on the mass (I'm looking for a qualitative rather than quantitive answer)? My inital thoughts were towards the centre of rotation, due to the tension on the string (and since the...

Homework Statement The displacement, y(x; t), of a tight string of length, L, satisfies the conditions y(0, t) = \frac{\delta y}{\delta x}(L,t) = 0 The wave velocity in the string is v. a) Explain what is meant by a normal mode. Give the form of the displacement, y(x; t), for the normal...

If dark energy is caused by quantum fluctuations, where does this energy come from? Also according to string theory mass is determined by the sum of a string's positive, vibrational energy and its negative energy from quantum fluctuations. Could it be possible to create a particle with negative...

When do these two fields of physics overlap other than when we discuss entropy of supersymmetric black holes? Does statistical mechanics or statistical physics support any aspect in string theory or vice verse? I have read some place that the string theory reduces to the standard model by doing...

Homework Statement Ideal rubber stirng with length L=1km.Ant is takng a walk on the string with speed v=1cm/s After every minute(Δt=60s) ,string is getting longer by ΔL=1km. 1)Will ant get to the end of string? 2)If yes,then how long it will take ? Homework Equations 1) So i used...

When plucking a string once on a string instrument (a guitar for example), I can understand that this creates a disturbance in the form of a (actually two) pulses that travels along the string. It makes sense to visualize this. Let's for simplicitys sake say that the string is 1 meter long...

Homework Statement Hi, everyone. Me again. This time I'm here to ask about the tension in the string on a massive pulley. We have a wheel of radius R with a moment of inertia about its principal axis of 2/3 MR2 , suspended above the ground on frictionless bearings. A massless string of...

Homework Statement This is a prelab question which I hope for some confirmation I'm thinking right. A vibrating string is vibrating in the fundamental mode. The question is to plot a graph with a succession of applied tensions T on the x-axis and the resultant length L of the fundamental...

Homework Statement A fuzzy-dicer makes an angle of θ = 49.6° with respect to the vertical. The mass of the fuzzy dice is 1.0 kg. What is the tension? 2. The attempt at a solution (deleted answer)

Homework Statement An inextensible string of length ##\ell##, whose mass per unit length is ##\rho## is hung between two points at the same height a distance ##d## apart (##d < \ell)##. Using the Euler-Lagrange equations and the first integrals, find the shape of the string when it is in...

Which do you think are the most promising alternatives?

Homework Statement A mass m whirls around on a string which passes through a ring, as shown. Neglect gravity. Initially the mass is distance r0 from the center and is revolving at angular velocity ω0. The string is pulled with constant velocity V starting at t = 0 so that the radial distance...

I am doing a project on string theory and my first task is to work out fundamental string solution from the I(10) string action in NS sector.I am following A.Dahbolkar, G.Gibbons, J.A.Harvey & F.Ruiz Ruiz, Nuclear Physics B340 (1990) 33—55. Why is it called fundamental string? I have not taken...

1.This equation in the link below refers to the small angle approximation regarding deriving the wave equation from Newtons laws from small amplitude waves in a single string with fixed tension. 2.http://imgur.com/NGSwzcl 3. I'm a bit rusty on the maths and have no idea how these...

Collision -- a ball and string form a pendulum... 1. A 1.0-kg ball is attached to the end of a 2.5-m string to form a pendulum. This pendulum is released from rest with the string horizontal. At the lowest point in its swing when it is moving horizontally, the ball collides elastically with a...

Homework Statement Consider a string of length L held fixed at both ends. The string can be shaken up and down and, at certain frequencies, the result will be a standing wave pattern on the string. Find the five longest wavelengths (call them λ1, λ2, λ3, λ4, and λ5) of the standing wave...

Homework Statement Given that a string is constrained such that dy/dx = 0 at x = 0 and unconstrained otherwise, what is the reflected and transmitted power? y is the deflection of the string from the x-axis. y_1 is incident wave, y_r is reflected and y_t is transmitted. Homework Equations...

Homework Statement A ball of mass 125g is attached to a string .900 meters long. It is then set into vertical circular motion with 38 RPM. What is the tension of the string at the top of the circle and at the bottom of the circle? Homework Equations ∑Fy = may = marad arad = v2/R =...