1
vote
1answer
81 views

How do I recover the 1D wave equation from the Lagrangian?

Consider small displacements, $y(x,t)$, of an element of a string (circled in red and shown below) from equilibrium. The force balance in the vertical direction yields: $$+\uparrow \Sigma F: ...
-3
votes
1answer
63 views

Finding the mass of 7cm string [closed]

If a string has $120$ g and length $40$ cm. I found that the linear mass density is given by $$120g/40cm=\ linear\ mass\ density$$ How do I use this to find the mass of a $7$cm of the same kind of ...
3
votes
1answer
76 views

Work done by vibrating string

figure from http://webusers.physics.illinois.edu/~m-stone5/mma/notes/amaster.pdf The string has fixed ends, a mass per unit length of $\rho$, and is under tension $T$. This source claims that "the ...
0
votes
2answers
218 views

Can somebody help me find the tension in this string? [closed]

My friends and I are debating over the correct answer for this particular physics problem. There's a pendulum with a $2kg.$ mass and a $5m.$ string attached to a ceiling at $53^{\circ}$ to the ...
1
vote
1answer
189 views

A block, a string and Newton's third law

So this is a general force diagram of the system shown. My question is, according to the third law, if the block is exerting a force of magnitude mg on the thread in the down direction, then the ...
1
vote
2answers
277 views

Guitar strings and temperature

I am investigating Mersenne's law with a guitar by varying tension (hanging weights) and string length. Will temperature change (room temperature to ~4°C) effect the frequency noticeably? If so, is ...
0
votes
1answer
136 views

The second resonance of string?

What is the relationship between "the second resonance " and string and the wavelength. Like in this question: if the length of the string is 2cm with second resonance, then what is wavelength?
1
vote
0answers
602 views

Neglecting friction on a pulley?

So, this is how the problem looks: http://www.aplusphysics.com/courses/honors/dynamics/images/Atwood%20Problem.png Plus, the pulley is suspended on a cord at its center and hanging from the ceiling. ...
3
votes
0answers
358 views

Shape of a string/chain/cable/rope?

The height of a string in a gravitational field in 2-dimensions is bounded by $h(x_0)=h(x_l)=0$ (nails in the wall) and also $\int_0^l ds= l$. ($h(0)=h(l)=0$, if you take $h$ as a function of arc ...
0
votes
1answer
188 views

Finding the acceleration of Block attached using tricky string setup

Below shown is a setup, and block B starts from rest and moves towards right with a constant acceleration. Does the acceleration differ for the blocks ? I am a bit confused because of the tricky ...
5
votes
1answer
394 views

Lagrangian density for a Piano String

So I'm trying to do this problem where I'm given the Lagrangian density for a piano string which can vibrate both transversely and longitudinally. $\eta(x,t)$ is the transverse displacement and ...
0
votes
1answer
347 views

How do we find the frequency of wave propagated along the x-axis?

I don't know how to solve question like this: A transverse wave is propagated in a string stretched along the x-axis. The equation of the wave, in SI units, is given by:y = 0.006 cos π(46t - 12x). ...
-1
votes
1answer
554 views

resonance frequency [closed]

A string has a mass per unit length of 9 10–3 kg/m. What must be the tension in the string if its second harmonic has the same frequency as the second resonance mode of a 2m long pipe open at one end? ...