This tag is for non-relativistic material strings, such as, e.g., a guitar string. PLEASE DO NOT USE THIS TAG for relativistic strings and string theory.

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1answer
37 views

Accelerations of Cylinders

I got a box hanging from a rope that passes through an ideal pulley that attaches to the superior part of a Cilynder and makes it rotate. An exercise asks me two things: a) determine the magnitude of ...
16
votes
3answers
335 views

Momentum of transverse waves on a string

In general, if a wave carries energy density $u$ with velocity $v$, it also carries momentum density $u/v$. I've seen this explicitly shown for electromagnetic waves and (longitudinal) sound waves. ...
-1
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0answers
19 views

Moment Of Inertia, Angular Acceleration [closed]

Consider a pulley and and a string is attached to the pulley with a mass hanging and then dropped. Explain why the acceleration is greater when you attach a string to a larger radius of a cylinder. ...
0
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1answer
25 views

How does string tension influence the harmonic spectrum?

Hey there fellow physicists & musicians! I have a question both physics and music related. How does the string tension affect the sound spectrum? More precisely, how do the respective ...
0
votes
3answers
74 views

Vertical circular motion/How can tension be negative?

This is a rock tied to a string spinning vertically. Here, $T+mgsin\theta = mv_1^2/r => T = mv_1^2/r-mgsin\theta$ Suppose I give it a velocity $v$ at the bottom. 1) At what angle $\theta$ will ...
7
votes
5answers
133 views

Astronauts on a tether

Recently, I went to a competition with a science test. One of the questions was as follows: Two astronauts (A and B) are tethered together in space. Simultaneously, Astronaut A pulls on the tether ...
10
votes
3answers
155 views

Are mechanical energy of an element of a rope and energy density constant in the case of mechanical waves?

I'm confused about energy driven by a wave. Consider a sinousoidal wave moving in a rope. In my view each element $dm$ of the rope follows a simple harmonic motion in time. That means that the ...
4
votes
2answers
189 views

Standing wave on a rope fixed at both sides: minus sign in the reflected wave

I'm studying stationary waves on a rope fixed at both sides. In some books I find that the wave function studied is the sum of incident wave $\xi_1(x,t)$ and of the reflected wave $\xi_2(x,t)$. ...
-1
votes
1answer
26 views

Is it possible to have two waves of different frequency on one string?

Would this change for different Hz, Wavelengths, Speeds, or amplitudes?
0
votes
2answers
59 views

Pseudo force/negative acceleration

The goal is to find $\boldsymbol {a_0}$ I already have the solution, however, I have a few questions. In the solution they have taken $\boldsymbol {m_2}$'s acceleration relative to the ground to ...
0
votes
0answers
12 views

Pulley Advanced Equilibrium Problem [duplicate]

How to show that M would have to be more than 8m
0
votes
0answers
21 views

Will the force acting be doubled? [duplicate]

If me and a man are holding a string, and I apply a force of 100N, the tension in the string would be 100N, and it would exert a 100N force on the man and an equal and opposite force of 100N on me. ...
1
vote
0answers
55 views

Plucking Guitar Strings [closed]

I was given this prompt: A musician frets a guitar string of length 1.5 m at x = 0.28 m with one finger, and simultaneously plucks the string at x = 0.14 m with another finger (raising it to a height ...
1
vote
3answers
92 views

What is the physical meaning of reduced mass?

If we stick two block masses by a string and pass it over a pully and let the blocks free then mathematically we can obtain that the whole weight on the pully is more if the blocks are kept at rest, ...
3
votes
1answer
71 views

What happens if I slowly lower a dangling object into a black hole?

I could've sworn I've seen this question before, but I couldn't find it. Suppose I have an object on the end of a really long string. I can slowly lower it near the event horizon of a black hole, ...
5
votes
3answers
125 views

Transverse Wave [closed]

Tranverse Wave is travelling in a string.
13
votes
2answers
175 views

Rope waves with a twist

In the picture you see a person walking a slackline. A slackline is a tensioned flatband of polyester. Typical tensions are between 1 kN to 15 kN depending on the length of the line. The lines are ...
0
votes
2answers
44 views

Force on a Massless String

Suppose we are just pulling a block with the help of a string which is massless. Now since the mass of the string is 0 the force exerted by us is transmitted without being diminished. So the equation ...
2
votes
0answers
24 views

Which supersymmetry principles make the axio-dilaton field in F-theory holomorphic?

I am following the lecture notes on F-theory by T. Weigand . On page 7 he states that when considering F-theory as the strong coupling limit of type IIB orientifolds with D-branes, the axio-dilaton ...
0
votes
1answer
35 views

Conservation of Angular Momentum for an Object Not Rotating

I have a point mass connected to a string with negligible mass. The point mass has mass $m$ and is moving at a velocity $V$. The string is of length $r$, and it is keeping the point mass tied to a ...
6
votes
1answer
99 views

Why do headphones tangle themselves whereas shoe laces untie themselves?

Why do headphones tangle themselves whereas shoe laces untangle or untie themselves? Why aren't we using the phenomenon to create headphones that tangle less and shoe laces that untie less?
0
votes
1answer
29 views

Pulley inertia momentum of inertia

Considering a pulley with some mass, or some friction, How can its inertia (or momentum of inertia) influence the tension on 1 rope? Which part of the rope is influenced? Before or after the pulley?
-1
votes
2answers
56 views

Spring pulley system

Hey can someone please help me with this question, the answer given is B and C, but my doubt is that the acceleration of both the masses should not be the same and $K_1x_1 = K_2x_2$ ...[equation 1] ...
1
vote
1answer
92 views

Spinning a string with a mass on the end. What makes the mass rotate parallel to the ground? [closed]

Say you use your hand to rotate a string with a mass attached to the end. The string will first become taunt and then the mass and string will move upwards until they are spinning parallel to the ...
0
votes
1answer
32 views

Rope tension definition

What is the exact definition of the tension of a rope? Here http://web.mit.edu/8.01t/www/materials/modules/chapter08.pdf the following definition is given The tension $T(x)$ in a rope at a ...
0
votes
0answers
28 views

Ramond-Ramond potential and field strenght

I have a doubt about R-R potential in Superstring theory. The known facts are (according many books, for example "Basic Concepts in String Theory" by R. Blumenhagen, D. Lüst and S. Theisen): in the ...
2
votes
2answers
34 views

Torque and a pulley

I'm supposed to find, symbolically, what the moment of inertia of the pulley is using $T_1, T_2, r,$ and $a$. Obviously the base equation would be the sum of the torques equals $Iα$. I have the ...
0
votes
1answer
46 views

What's the required tensile strength for a wire?

I want to horizontally stretch a 50 meters wire rope and slide 100 kg object from side to side. What should be the minimum tensile strength (or carrying capacity) of the rope to be able to hold the ...
3
votes
1answer
33 views

Slackline tangling

This question is about random formation of knots in a systematically tied rope. I will give some background, hope that does not make it off-topic. In climbing (and sailing) one has to store very long ...
4
votes
4answers
1k views

What Keeps a Pendulum Moving In a Circular Path?

From the figure, we know that $F_{net} = mg\sin\theta$. Now, this force $\vec{F_{net}}$ is in the direction of the velocity $\vec{v}$ of the bob, both are tangent to the path. Therefore, the net ...
3
votes
2answers
51 views
10
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2answers
1k views

How can you make harmonics on a string? [duplicate]

For an oscillating string that is clamped at both ends (I am thinking of a guitar string specifically) there will be a standing wave with specific nodes and anti-nodes at defined $x$ positions. I ...
1
vote
0answers
27 views

Standing Waves in a String of two Linear Densities

Given a string with sections of two linear densities like this: Does the point where the two linear densities meet have to be a node if a standing wave is produced? Are there alternatives? Could I ...
1
vote
1answer
38 views

Dependence of tension (considering a pulley system) on the mass of loads

Consider the diagram below All circles are pulleys, which are fixed at the ceiling. M represents an engine (with a certain power) that is pulling the cable. C and D are weights. The acceleration of ...
1
vote
2answers
63 views

Condition for looping the loop

Consider a ball tied to a string and it is imparted a velocity we have studied that condition for looping the loop is that tension at the uppermost point must be zero, but why is this condition ...
1
vote
4answers
99 views

When is tension positive?

A 5kg mass is hanging from the roof of an elevator accelerating downward at a speed of 1.65 m/s^2 what is the tension of the string (ignore friction, string mass, and air resistance) ? I used this ...
0
votes
1answer
55 views

Finding mass attached to the string

I'm given the following problem: One end of a string with a linear mass density of 7.60* 10^-4 is connected to an oscillator with a frequency of 50.0 Hz. The other end is connected to a hanging ...
3
votes
2answers
65 views

shape formed by a stiff string with ends pinched together [closed]

Suppose I have a string of length $L$ with a bending energy given by $$E=\frac{1}{2}\epsilon \int_0^L ds\, (\mathbf{R}''(s))^2 $$ Let's say I form a bight with it by pinching the ends together, ...
0
votes
3answers
65 views

Conditions for the tension to vary in the rope

What are the conditions for the tension to vary in the rope. I have read below conditions 1. rope has to have some mass 2. rope is accelerating I get the 1st ...
1
vote
1answer
80 views

Normal Ordering in String Theory: Polchinsky vs. all others

Polchinsky defines normal ordering in string theory as: $$:X^\mu(z,\bar z)X^\nu(w,\bar w): = X^\mu(z,\bar z) X^\nu(w, \bar w) + \frac{\alpha'}{2} \eta^{\mu\nu} \log |z-w|^2$$ and for more ...
0
votes
1answer
47 views

Tension in a vibrating loop

Consider a super basic 1D vibrating string, with standing waves on it. The string has length $L$, and the wave propagates at a velocity $v$. The fundamental frequency $f_1$ is given by $$f_1 = ...
1
vote
2answers
101 views

Why can we assume, when dealing with tension, that the mass of a rope is $0$ but still assume that there are forces on it?

I started studying tension and I can't understand the following concept: If I have two objects $A,B$ collegated by a rope, where $A$ applies a certain force $\vec{F}$ on it, I would have that the ...
0
votes
0answers
43 views

Interpreting solution of the 1-D wave equation (vibrating string)

An ideally flexible string of length $x=L$ vibrating in one dimension ($xy$ plane) in the absence of gravity obeys the wave equation \begin{equation} \dfrac{\partial^2 y}{\partial t^2} = c^2 ...
0
votes
0answers
38 views

How was the “vibrating string” studied?

The vibrating string is used to derive a lot of theory regarding strings, such as the theory about harmonics. However, since the string movement and specifically the phenomenon of harmonics seems ...
1
vote
2answers
46 views

Tension at topmost point of a vertical circle

I read that for a body to move in a vertical circle, the minimum tension needed is 0 at the topmost point. Can someone explain to me what it means to have positive or negative tension on top. I'm not ...
0
votes
1answer
83 views

Ball suspended on elastic string (finding tension)

A ball (of mass $m$) is suspended by an elastic string. It accelerates upwards with an acceleration $a$. Find the tension in the string. Taking upwards as positive, we have $$T - mg = ma \iff T = ...
0
votes
2answers
115 views

Few questions related to Tension

I am struggling with the concept of tension in a rope. Below specific questions. I am understanding tension to be an elastic force between rope molecules. If so, is it fair to say the net tension ...
0
votes
0answers
40 views

Classical string as a limit case of elastic quantum states superposition

The usuall way to "half-popularly" show that the quantum mechanics formalism is not unconnected to the classical mechanics is to demonstrate a classical case as a limit of a quantum case. The main ...
0
votes
2answers
277 views

Vibrating string, free end boundary condition

When discussing the vibrating string problem with one end (or both) free to move in the vertical direction but constrained in the longitudinal direction (achieved by placing the "free" end in a ...
1
vote
1answer
46 views

Boundary behaviour of a mechanical wave

Let us assume we have a taut rope and I introduce a pulse in it by whipping one end. Now if instead of a clamp, I have tied the other end of the rope to a denser rope, a part of the energy is ...