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Questions tagged [string]

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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Frequency of longitudinal waves on a string

I recently heard the composer Ellen Fullman on her Long String Instrument, which consists of steel wires of approx. 20 m length played by rubbing/stroking the string longitudinally. Changing the ...
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0answers
23 views

At what amplitude is maximum tension produced? [closed]

While I was studying angular SHM, a question struck me. Suppose there were two masses $m$ connected by a light rod at a distance $\frac{l}{2}$ from the centre of the light rod. If the centre of the ...
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3answers
57 views

Work-Energy Problem: A ring pulley and mass system, in which the ring is sliding on a vertical rod [closed]

A heavy ring of mass $\;m\;$ slides on a smooth vertical rod and is attached to a light string which passes over a small smooth pulley distant $\; 'a' \;$ from the rod and has a mass $\;M(>m)\;...
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1answer
36 views

Pulley in a lift [closed]

. This might be in an easy question.But in the the given figure we write mg -T = ma now suppose the lift is accelerating with 2 m/s^2 we get T = m(g-a)~m(6). now if the lift start accelerating/...
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1answer
41 views

Tension in a string moving in elevator

A lift can move in $x$ axis and also in $y$ axis. A bob of mass m is suspended with inextensible thread inside the ceiling of elevator. Determine tension $T$ in the string when elevator moves in $x$ ...
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23 views

At what rate is tension released from a plucked string (eg. guitar string)?

Tension in a plucked string (such as a guitar) dictates many of the important changes that occur in the sound of the string over time. eg. It causes a pitch bend, a change in inharmonicity, and ...
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0answers
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What is the resultant force acting upward on the point of contact under an elastic deformation?

The situation here is you have an elastic string (or a rubber band) fixed at two ends A and B. A•-------------------------------------------------•B An object is ...
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0answers
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String conservation with springs

I was trying to solve this Problem that asked to find the period of small oscillations for this system. To do so I used the fact that for a massless pulley with strings around it, the sum of the ...
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1answer
27 views

Tension in a string attached to a spring with deformation at a point

I am trying to calculate the tension in a string in the configuration shown in the diagram below. Here is a verbal description of the setup: The string is fixed at one end with the other end connected ...
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1answer
45 views

Dropping a rope in a black hole [duplicate]

If there is a spaceship hovering above a black hole so that it can get away, what would happen if the spaceship connected a rope to itself and dropped the rope in? Could you pull the rope out?
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4answers
38 views

Tension in string due to two opposite forces [duplicate]

If you attach a ideal string to a wall and pull it with force F, there should be a tension T=F in the string. And the string will apply force F on the wall too. But what if there are two persons ...
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1answer
48 views

How does velocity being given to the bob here create tension in the string? [closed]

Based on intuition, the lesser the velocity the bob is initially given, the sooner will the string slack. I don’t understand how the velocity the bob is given initially is related to tension being ...
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4answers
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Newtonian mechanics. If I'm inside a wagon and I pull a spring connected to the wall, will the wagon move? [closed]

Suppose the mass of the wagon is very small. There's a spring connected to the wall inside the wagon. If I pull the spring, does the wagon move?
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1answer
42 views

Friction in pulleys

The moment equation of a pulley with a rope applying tension on both sides is as follows: $$I\alpha = f + T_1R - T_2R$$ ( $I$ - moment of inertia; $\alpha$ - angular acceleration; $f$ - friction ...
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1answer
35 views

How can a rope's tension be at a maximum as a body is about to move up a slope in the rope's direction? [closed]

Note: I do NOT need this exercise's answer. I have no problem working the math out and noticing the truth of my title. A box of mass 0.5 kg is placed on a plane which is inclined at an angle of 40 ...
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0answers
21 views

1D string reflection and transmission phase

Ok, I must be missing something very obvious here. After applying the boundary conditions, we can write: $$ A_R e^{i \delta_R} = (\frac{v_2 - v_1}{v_1 + v_2}) A_I e^{i \delta_I} $$ and $$ A_T e^{...
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2answers
71 views

How do I write the equation of motion for a pulley on a fixed rope? [closed]

I've got complex dynamics problem I'm trying to solve, but the crux of my problem at the moment is describing the path a pulley would take on a rope of fixed length. Assume the rope is fixed at ...
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4answers
119 views

Why is the work done by tension in a pulley always zero?

Consider a pulley with a rope around it connecting two masses. According to this post the work done by the rope on the two mass system is 0. The explanation of this post makes sense to me; the blocks ...
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2answers
54 views

String and pulley problem doubt [closed]

When we apply a constant force on the massless string as described in the left image, the tension T = F. My doubt : isn't applying constant force similar to a block m2 hanging in the 2nd image. What ...
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2answers
80 views

To find the equation of Motion of a Simple Pendulum using Lagrangian mechanics [closed]

The Equation of the Trajectory of a particle can be obtained by eliminating the variable $t$ as we are doing in the equation of Trajectory of a parabolic Projectile. So, my question is if the equation ...
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0answers
33 views

Foucault's pendulum; ball bearing?

Is is a ball bearing necessary to prevent the cord from twisting in a Foucault pendulum?
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1answer
42 views

Work from string wrapped around cylinder [closed]

A cylinder, on a level surface angularly accelerates as a string wrapped around is put under tension. Because this string causes the cylinder to roll without slipping, the tension force cannot to any ...
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1answer
73 views

A problem in newtonian physics [closed]

Hello! I have solved problem 89 using analytic way, i.e, the length of the string will always be constant, so repeated substitutions and differentiating will make way(i got answer as "c"). But is ...
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2answers
29 views

Would equal balance at same height when hung on a balance?

This is based on a question from the gravitation course on Brilliant. As you can see in the diagram below, we have 2 weights hung on a pulley. It is given that: Neither one accelerates when you let ...
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0answers
28 views

Boundary conditions of spun string

Problem: Consider a string with mass per unit length $\rho$ and length $L$. It is spun about one end, with angular velocity $\omega$ , such that the motion is in a plane (we neglect gravity). Let $x$...
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0answers
75 views

Considerations for formulating Lagrangians in general

My question albeit trivial is something I wish to understand better. Given a system either say 3 masses, 2 masses and a pulley (with mass), and 2 masses attached via a string with mass $m$ (and ...
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1answer
30 views

Equation of constraint - Falling disc unrolling from an attached string

Where does the equation of constraint below come from? I've tried to rationalize it, but the angle will be 0 more than one time as the string unrolls, even though y will keep going down (right?), not ...
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1answer
33 views

Reflection of transverse wave from free end?

I have been using David Morin' drafts on waves along with French's wave book and Fox Smith's book for my undergrad wave course and one thing I don't understand is the physical intuition behind ...
1
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1answer
39 views

What's the relation between the tensions on a rope around a non-ideal pulley? [closed]

I know that on one side of the pulley the tension must be larger to let the torque do its job and rotate the pulley. But how does the relation look like? $$T_1 = k \cdot T_1'$$ What's $k$?
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2answers
140 views

Tension in a string, at an angle [closed]

This was a question on a mechanics exam. Part i wants me to assume that the tension in both parts of the string is the same. Even though I got the correct answer( 18.9N) by assuming so, I don't ...
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1answer
38 views

Rings threaded onto strings

This is a follow up question to a question I asked a few weeks ago (Normal contact force with a light string) When a ring is threaded onto a light string, we know it experiences a contact force. Does ...
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0answers
53 views

How long does it take for a wave pulse on a string to get reflected from rigid boundary?

This question arises from analysis of standing waves.The incident wave has the equation $$y=Asin(kx-\omega t)$$The reflected wave has the equation$$y=Asin(kx+\omega t +\pi)$$When determining the ...
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1answer
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How to find the equation of motion for a string threaded through the centre of a table?

A string of total length $l$ is threaded through a hole in the centre of a frictionless horizontal table and then released. How would one go about finding the vertical equation of motion for this ...
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1answer
82 views

Is the first harmonic the prevalent frequency? [closed]

Why, when we play a string, almost all of the energy we give them is ''used'' in the first harmonic (the fundamental frequency) rather than be distributed between all of them?
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3answers
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In a ball with random thread/strings, how does the density of threads/strings change with radius?

A large plastic ball full of holes is given. (So the holes are in a plastic shell.) Straight threads connect these holes randomly, by passing through the interior of the ball/shell. For a big ball or ...
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2answers
63 views

Tension in a string in free fall

A body is attached to another with a string and both are in free fall. How does the tension in the string being zero make sense conceptually?
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1answer
49 views

Variation of Tension in a rope [closed]

In the 1st picture we consider the tension in the rope to be the same on both the sides. However in the second picture we take it to be different. Why? If we have to consider a general case then why ...
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1answer
33 views

Ambiguous Constraint equation

This is from the solution manual of some problem of Kleppner's book. I didn't understand how the constraint equation came about to be. First of all, I don't see how that equation is equal to the ...
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1answer
43 views

Why the capstan equation is exponential? [closed]

Does anybody knows any intuitive explanation about the reason that the capstan equation is exponential and not, as expected, linear?
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4answers
105 views

How to resolve velocity components?

In the arrangement shown in the figure, the ends P and Q of an inextensible string move downwards with uniform speed $u$, pulleys A and B are fixed. With what speed does the mass M move upwards? My ...
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0answers
50 views

Prove from first principles that a guitar string will vibrate at a constant frequency

From experience I am aware that a taught string will generally vibrate with a constant frequency. I wanted to prove this by considering the relation of distance from the resting position, and its ...
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1answer
49 views

Can this sum be done without integrating?

As by using conservation of mechanical energy, we can just be concerned about the final and initial position and the velocity could be found out. Am I not right? But I am not getting the correct ...
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1answer
38 views

Do pulleys have no effect on atwood machine?

I was given the following example for an atwood machine: We should calculate the accelaration of the masses. The given solution to this problem was the same as like there is just one pulley: $$a=\...
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2answers
44 views

Real Pulley and Newton's Third Law

In a real pulley with two masses hanging from either side, the pulley rotates due to a non-zero torque, which I understand is caused by friction on the rope. I understand that if each mass was ...
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1answer
52 views

A spinning pendulum [closed]

I just thought of a scenario : We rotate a sphere that is hanging from a string about vertical axis and then allow it to oscillate like a pendulum . Will its time period differ from a sphere ...
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3answers
153 views

Vibrating string as a dynamic system

It's known first order dynamical systems had one energy storage (example C, in RC circuits) these systems act as a filter but don't resonate, on the other hand a second order system had two energy-...
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4answers
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If all harmonics are generated by plucking, how does a guitar string produce a pure frequency sound?

A guitar is a plucked instrument and it is played by plucking a string at an off-centre point fixed at two ends. In general, Fourier analysis tells that all harmonics (the resonant frequencies of the ...
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3answers
47 views

Force required to lift a block [duplicate]

Let us consider block of mass $m$ hanging by rope with force $T$. When no other horizontal and vertical forces are acting on a block, the block is at equilibrium if $$T=mg.$$ And if the rope is pulled ...
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1answer
37 views

How to draw diagrams of Path, velocity and time for a complex problem?

What does an approach or a solution strategy look like for the following problem: Two point-shaped bodies with the masses m_1=100g and m_2=200g are connected to a string of 30 cm length and lie on a ...
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1answer
27 views

To isolate a particular mode of vibration in a standing wave on a string

Suppose a string bound between two rigid end-points is vibrating and it is a combination of a number of normal modes of vibration, is it possible to isolate a particular mode of vibration in wave by a ...