# String Definition and 47 Discussions

In molecular biology, STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) is a biological database and web resource of known and predicted protein–protein interactions.
The STRING database contains information from numerous sources, including experimental data, computational prediction methods and public text collections. It is freely accessible and it is regularly updated. The resource also serves to highlight functional enrichments in user-provided lists of proteins, using a number of functional classification systems such as GO, Pfam and KEGG. The latest version 11b contains information on about 24,5 million proteins from more than 5000 organisms. STRING has been developed by a consortium of academic institutions including CPR, EMBL, KU, SIB, TUD and UZH.

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1. ### A Mechanism which pulls a specific amount of string (yarn) mutiple times

Yarn Grippers, Linear motion equipments Motors
2. ### Morin's mechanics problem 2.3 (motionless chain)

In his solution, Morin solves the problem as the hint suggests: cutting the chain into small pieces, taking the component of the external forces along the curve (which is just the component of gravity here) and summing up an in integral, obtaining 0. He then claims that because the "total...
3. ### Vertical spring connected between two bodies with a rope above them

Question: A string spring is connected between two bodys with a rope above them. M1 = 25Kg M2 = 50KG Distance between them is 100m. I answered a bit and got to the point where the distance between the two masses are 110m ( the mass below got 10m lower and is on balance, I mean, acceleration = 0...
4. ### Comp Sci Evaluating if a given integer can be calculated from a list containing numbers and operators (Recursion)

Here's what I've done: Mentor note: replaced icode tags with code=python and \code pair. def valid_braces_placement(s, L): if len(L)==0: return False string = '' for element in L: string = string + str(element) D = ['+','-','*'] return...
5. ### I Movement of a guitar string at relativistic speeds

Hey! I'm and undergrad in the third year of my applied physics program. I'm taking a course in Special Relativity, and due to Corona the exam has been replaced by a pretty free project where we delve deeply into a topic related to the course. I'm interested in music, so my professor suggested I...
6. ### Reflection of inverted waves to form a standing wave

Standing waves in a string fixed at one end is formed by incoming and reflected waves. If reflected waves are 180° out of phase with incoming wave, how could they combine to give an oscillating wave? Shouldn't it be completely destructive interference all the time across the whole length of string?
7. ### How do I read this equation for air friction/drag on an object?

I am trying to understand an excerpt from an article describing the vibrations of a string (eg. guitar/piano) which reads as follows: This is basically the wave equation with Δm representing a small piece of mass from an interval of the string and two forces added to the right side. He...
8. ### Mechanics: A plank on a spring causing two cylinders to undergo harmonic motion (rotation)

Here is the picture on the system. I have to find the period (T). The masses, R and dX is given. The systam at first is at rest, then at t = 0 we pull the plank to dX distance from its originial position. In the thread...
9. ### B A man climbing up a rope

A man tries to climb up a rope with acceleration, ## a ##. What does he actually do to climb up? My Interpretation Let the man pull the rope at point A. So the Point A will pull the man with Tension, ## T ##. But at the same time the man is holding the rope, so there will be some normal...
10. ### Seemingly simple Physics 2 wave question (third harmonic frequency)

I cannot find the correct answer anywhere online and the answer I keep getting is 5.4 (incorrect) Please show me the process to get to the answer! Thank you
11. ### I Alternative approach to analyzing a massless string

Consider a massless string which can rotate about a fixed pulley (first picture). The coefficient of static friction is μ. Assuming that the motion is impending, the goal is to find the equation that describes the variation in tension of the string. ( T2/T1 = eμΦ where Φ is the subtended angle.)...
12. ### I Table tennis racket design

https://en.m.wikipedia.org/wiki/Table_tennis_racket Would like to know the impact for the table tennis game if the racket is changed to a String type Lawn tennis or Badminton racket? Thanks & Regards, Prashant S Akerkar
13. ### Harmonic Frequency of a String

Homework Statement A string (m = 1 kg) fixed at both ends is vibrating in its second harmonic mode. If the length of the string is 2 m and it feels 50 N of tension, which of the following is NOT a possible harmonic frequency for this string? a) 1.25 Hz b) 2.5 Hz c) 5 Hz d) 10 Hz e) 20 Hz...
14. ### Finding the tension of a rope given the mass of a pulley

Homework Statement mass of pulley is 8 kg Homework Equations m1a=T m2g-T=m2a The Attempt at a Solution I solved question with neglecting mass of pulley but should I?
15. ### Falling solid cylinder with string

Homework Statement Homework Equations m:mass of solid cylinder T: tension in string w:angular velocity The Attempt at a Solution m(g-a)=T mg-ma=T a=v^2/r=w^2r now what?
16. ### B Showing/proving a physical relationship

I derived a relationship between frequency and tension of a string, accounting for tension's effect in the linear density of the string. So in a nutshell, the equation is more complicated and is in the form of f^2=aT^2+bT (f is frequency, T is tension, ab are constants involving the control...
17. ### Resolving forces involving an elastic string

Homework Statement A light elastic string of natural length 0.3m has one end fixed to a point on a ceiling. To the other end of the string is attached a particle of mass M. When the particle is hanging in equilibrium, the length of the string is 0.4m. (a) Determine, in terms of M and g (take g...
18. ### Newton's 3rd Law (Pulleys - 1)

Hi, I'm new here. Could someone provide some guidance on how to start this problem?
19. T

### Tension required to tune a string to the note of ##E_2##

Homework Statement State the boundary condition which must be met at a point where the string of question 2 is fixed. Hence find the real standing wave solutions to the wave equation, and determine the allowed oscillation frequencies, when such a string of length ##L## is fixed at its ends...
20. T

### Understanding Tension on a Pulley

Homework Statement Problem image: https://prnt.sc/gvhjso In this case I have to find the reaction forces at the point E (the Fx, Fy, and the Moment at point E) by using the given data. The 20kN forces at the load AC are concentrated, and are 1.8m far from each other. The tension of the cable is...
21. ### What is the mass of the book?

Homework Statement (Problem #1 on this page.)[/B] Homework Equations ##v=\sqrt { \frac { T }{ \mu } } =\lambda f## The Attempt at a Solution I don't think there is enough information, ##v=\sqrt { \frac { Mg }{ m/L } } ## m, the mass of the string is not given
22. ### Conservation of the string length in pulleys

Homework Statement This is a common massless string and pulleys problem. I'd just like to understand why, according to the solution, l_2 + 2l_1 = constant. It doesn't seem to me that two times the l_1 lenght is equivalent to l_2. Can somebody explain? Homework Equations The Attempt at a...
23. ### Force of rope on a pulley

Homework Statement I'm having trouble understanding an example given in K&K's Intro to Mechanics textbook. 'A string with tension ##T## is deflected through an angle ##\theta_0## by a smooth fixed pulley. What is the force on the pulley'. I don't understand how (in the first picture) they...
24. ### Wave speed for non-uniform density?

Homework Statement A long rope with mass m = 10 kg is suspended from the ceiling and hangs vertically. A wave pulse is produced at the lower end of the rope and the pulse travels up the rope. (a) Explain why the speed of the wave pulse change as it moves up the rope; does it increase or...
25. ### I Macroscopic versus microscopic standing waves

I have read the description of electrons as standing waves based on an analogy with a string vibrating at its natural frequencies: thus the different quantum levels are akin to the tones or harmonics of the string, right? So far, so good, but then I have seen contradictory complementary views...
26. ### Phase speed of the wave

Homework Statement transverse wave is traveling through a wire in a positive direction of the x-axes. Distance od the wire particles in the motion of the wave can be described as ##y(x,t)=53*10^{-6}sin(188t-3.14x)## Find the ratio of the phase wave speed and maximal speed of the wire particles...
27. ### Required conditions for vertical circular motion to occur?

For the case of a particle attached to an inextensible string which is hanging at rest and then provided an impulse horizontally, what conditions must the system meet in order to allow for COMPLETE circular motion. Im well aware the tension at the apex of the motion must be satisfy one of the...
28. ### Equilibrium Tension Along a Curved String

Homework Statement A light inextensible string of length l hangs on two pegs attached to parallel walls separated by a height. A small frictionless pulley of weight Wp is attached to a block of weight Wb. When it is placed on the string, the string becomes taut and pulley runs on the string...
29. ### Finding time in a pulley system

Homework Statement A horizontal bar with a mass of 3.2 kg and a length L of 64 cm is rigidly mounted to a vertical spindle of negligible mass such that the two objects spin together. The spindle has a diameter of 2.0 cm, and it is attached to the bar a distance of L /4 from its centre of mass...
30. ### Question about mg on oscilations course

On a test our teacher asked about a system composed of (string -> mass -> string -> mass) hanging, that began to oscillate up and down. We all considered weight (mg) when applying Newton's second law to find the associated differential equation. When we met our teacher again he said that we...
31. ### Predict Damping Coefficient?

Is it possible to predict the damping coefficient of a string using a mathematical simulation that included the string's diameter, length, frequency (and therefore tension), material density, and elastic modulus (if not also its Poisson's ratio) as opposed to simply looking at the amplitudes of...
32. ### Predicting Initial Length of String Needed Before Stretch

I have put together an equation whose purpose is: With a desired 'magnitude of static friction' ( μ_s ), 'fundamental frequency' ( f ), and 'tension' ( T ), initial conditions such as 'string breakover angle' ( Θ_0 ), 'nut-tuner distance' ( L_{h,0} ), and 'string diameter' ( d ), and...
33. ### Question about standing wave

By considering the superposition of two waves propagating through a string, one representing the original or incident wave and the other representing the wave reflected at the fixed end, if both ends of the string is fixed then the waves can reflected and travel back and forth. Standing wave can...
34. ### Reflected wave from free end

A wave pulse on a string moving from left to right towards a free end will reflect and propagates from right to left with the same speed and amplitude as the incident wave, and with the same polarity. My question is, why the slope and the vertical force must be zero at the free end? If the...
35. ### Question about force in transverse waves on a string

In deriving wave equation or power transmission of wave transmitted by a string, it is usually stated (with some assumptions) that the transverse force on a point of the string is proportional to the slope at that point. An example is given in p.20 of this notes...
36. ### What is the tension in the string?

Homework Statement A string is connected to a box A mass M at its left end and a box B mass 2M at its right end. Boxes A and B start pulling in opposite directions at the same time with forces which are time dependent and described by functions F(t)=Ct for box A and F(t)=Dt for box B. Values of...
37. ### Physics Solo Physicists

Hello everyone, just a quick question: I have heard that it is impossible to do research in physics by yourself anymore. I heard that "The days of Einstein are gone" and that nowadays in physics, especially string and quantum relativity research, everyone publishes in groups. I feel like this is...
38. ### Tension and Velocity

Hello, I was recently reading a physics book and was told that, if a string were to hang down with a weight attached to it, its tension would be the mass times gravity. However, if it were to gain some velocity and move from left to right, the tension would increase enough so that the string...
39. ### Transverse wave in a string

Homework Statement http://puu.sh/frpk5/eae7bce2e3.png [Broken] Homework Equations v = sqrt(T / (m / L)); The Attempt at a Solution 7.86 g / cm^3 = 7860 kg / m^3 T = v^2 * m/L T = 160 ^ 2 * 7860 which is a huge number I have no idea where the diametre plays a part.
40. ### Tension in a string between two blocks

Homework Statement Two masses M1 = 6.90 kg and M2 = 3.10 kg are on a frictionless surface, attached by a thin string. A force of 48.1 N pulls on M2 at an angle of 31.3° from the horizontal as shown in the figure. Calculate the tension T in the string. Homework Equations T=ma a=g(m2/(m1+m2))...
41. ### Tension of a string attached to an instrument inside rocket

Homework Statement Suppose the rocket is coming in for a vertical landing at the surface of the earth. The captain adjusts the engine thrust so that rocket slows down at the rate of 2.40m/s2 . A 6.00-kg instrument is hanging by a vertical wire inside a space ship. I don't know if there are any...
42. ### Wave speed dependents

Homework Statement A bit confused here as to what wave speed is dependent on. At first I learned that v = λƒ, and a couple of pages later in my textbook I find that v = √(τ/μ). Also, I found that speed is only dependent on the properties of the medium, specifically its elasticity and mass...
43. ### Wave speed of a stretched string

A bit confused here as to what wave speed is dependent on. At first I learned that v = λƒ, and a couple of pages later in my textbook I find that v = √(τ/μ). Also, I found that speed is only dependent on the properties of the medium, specifically its elasticity and mass. Where does wavelength...
44. ### Maximum tension on a string

if one string can hold a block of 100kg, how much weight can two strings connecting the ceiling and one single point hold a block?? is it 200 kg? if yes, then what about one string connecting the ceiling and one single point of the block two times, three times or more? [im sorry if the grammar...
45. ### MATLAB [Matlab] How to use inputdlg string variable in text file?

I am trying to display the input that I enter into the dialog box from "inputdlg" function into a text file. This is what I've so far: prompt={['What is your name?']}; title = 'Name Machine'; answer = inputdlg(prompt, title); name = answer{1}; fileID = fopen('NameMachineFive.txt', 'w')...
46. ### Two masses on frictionless table with one string connecting both masses on ground and the other

Homework Statement [/B] A solid cylinder of mass m and radius r lies flat on frictionless horizontal table, with a massless string running halfway around it, as shown in Fig. 8.50. A mass also of mass m is attached to one end of the string, and you pull on the other end with a force T. The...
47. ### Is the Polyakov action invariant under general coordinate transformation on the target space?

The Polyakov action, S=\frac{1}{4\pi\alpha^\prime}\int d^2\sigma\sqrt{-h}h^{\alpha\beta}G_{ij}(X)\partial_\alpha X^i\partial_\beta X^j has the local symmetries, diffeomorphism on world sheet and the Weyl invariance. But is diffeomorphism on the target space also a symmetry? The target space...