What is Shm: Definition and 501 Discussions

The MIT Shared Memory Extension or MIT-SHM or XShm is an X Window System extension for exchange of image data between client and server using shared memory (/dev/shm). The mechanism only works when both pieces are on the same computer.
The basic capability provided is that of shared memory XImages. This is essentially a version of the ximage interface where the actual image data is stored in a SysV shared memory segment, and thus need not be transferred across the socket to the X server. For large images, use of this facility can result in some real performance increases.
Additionally, some implementations provide shared memory pixmaps. These are two-dimensional arrays of pixels in a format specified by the X server, where the image data is stored in the shared memory segment. Through use of shared memory pixmaps, it is possible to change the contents of these pixmaps without using any Xlib routines at all. Shared memory pixmaps can only be supported when the X server can use regular virtual memory for pixmap data; if the pixmaps are stored in the on-board memory of graphics hardware, an application will not be able to share them with the server.
In the 1.15 release of the X.org server the MIT-SHM extension gains two additional requests: 'X_ShmAttachFd' and 'X_ShmCreateSegment', to be able to pass shared memory through file descriptors from client to server and from server to client, reducing the number of copy operations further.

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  1. S

    SHM - Pendulum and Mass on a spring

    I have only be able to write something like: 2x(2π√(l/g)) = 2π√(m/k) 2π is a constant therefore; 2x(√(l/g)) = √(m/k) You could square both sides; 2^2x(l/g) = (m/k) But now I'm lost as to how to proceed. PS- Book answer is B Thanks
  2. J

    I Should we consider GPE in the vertical case of SHM?

    For the horizontal case of SHM, we only need to consider KE and EPE. But should we also take GPE into consideration when we are dealing with a vertical case?
  3. N

    Proving SHM for charged spring mass system in electric field

    For part (f) Solution is I don't understand why the bit highlighted in yellow is true. Would anybody be kind enough to help.
  4. uSee2

    Pan suspended by a spring (Energy + SHM)

    I have successfully completed parts A, and B, however, I am confused on Part C. Here was my attempt and the answer key's attempt: My attempt: Since I correctly knew the speed after the collision, and the gravitational potential energy after the collision if I set h=0 at when it was at rest...
  5. C

    Solving the SHM differential equation

    I am trying to solve this homogenous linear differential equation . Since it is linear, I can use the substitution . Which gives, (line 1) (line 2) (line 3) (line 4) (line 5) Which according to Morin's equals, (line 6) However, could someone please show me steps how he got from line 5 to 6...
  6. C

    Deriving position function for object in SHM

    For this problem, How did they get that formula shown? My working is, All the solutions wrote was, Many thanks!
  7. Curiosity_0

    B Correct SHM Equation: Does € Matter?

    A textbook I am using gives the basic eqn of motion of shm as follows : X = Asin(wt + €) V =Awcos(wt+€) But other textbooks and online sources are interchanging sin and cos in above equations, so which is the correct one? Or does it depend on the phase constant €?
  8. tbn032

    B Is simple harmonic motion also a pure translatory motion?

    Is simple harmonic motion also a pure translatory motion?"A rigid body moves in pure translation if each particle of the body undergoes the same displacement as every other particle in any given time interval" [Halliday and Resnick, Physics].If not,then how does shm deviate from this definition>
  9. S

    Angular frequency of a mass performing SHM

    When given a small displacement ##x##, the equation for m is: (i) N sin θ = m.a where N is the normal force acting on the ball and θ is angle of the ball with respect to vertical. (ii) N cos θ = m.g So: $$\tan \theta = \frac a g$$ $$\frac x R = \frac{\omega^{2} x}{g} \rightarrow \omega = \sqrt...
  10. Tea_Aficionado

    Why don't we account for energy lost in collision here? SHM

    We know that the Ug is converted to KE and Us. I thought that since the system loses energy after the collision that we shouldn't use the equation hnew= delta x + h. I thought instead that maybe the h we should use is xmax, because that's when there is maximum Ug and there is no other energy...
  11. dahoom102

    SHM Find amplitude from ω and x

    Hi, I have no idea what formula to use while given these values, basically, it fits no formula. Any thing could help? Many thanks in advance Correct answer is 65
  12. P

    Getting the equations of motion for this SHM problem

    Summary:: I have come across a situation where I seem to get different equations of motion for an oscillating system. Please do help me find out where I went wrong. *I am not asking how to solve the problem* I am going to consider 4 parts of the cylinder's motion, as listed below. (There is...
  13. Hamiltonian

    Dropping a block on another block which is performing SHM

    at the mean position of the original block, its velocity is ##V = \omega A## once the new block is dropped we can conserve momentum in the horizontal direction $$m\omega A = (2m)v$$ $$v = \frac{\omega A}{2}$$ where ##v## is the common velocity of the blocks. but if instead of conserving linear...
  14. Leo Liu

    SHM retarded by friction

    Solution in 2ed manual: Solution in 1ed manual: Could someone explain why the work done by friction is multiplied by 2? I get that the distance traveled by the block in one cycle is greater than ##x_f+x_i##, but why is the coefficient two?
  15. Hamiltonian

    Real life example of the composition of two SHMs with same angular frequency

    Under the topic of simple harmonic motion comes the composition of two SHM's with the same angular frequency, different phase constants, and amplitudes in the same directions and in perpendicular directions. composition of SHM's in same direction: say a particle undergoes two SHM's described by...
  16. yucheng

    Visualizing the SHM of 2 blocks attached by a spring

    From Kleppner's Intro to Mechanics (Example 4.7, wording not exact): Two identical blocks a and b each of mass m slide without friction on a straight track. They are attached by a spring with unstretched length l and spring constant k; the mass of the spring is negligible compared to the mass of...
  17. Leo Liu

    A piece of clay stuck to a SHM oscillator

    I don't get why the total mechanical energy is not conserved in this situation. When the length of the spring reaches the maximum, the speed of the block is 0 and we have the following equation: $$E=K+U=1/2mv^2+1/2kA^2,\text{where A is the amplitude} \implies E=1/2kx_{max}^2$$ I can't see why...
  18. Prabs3257

    Momentum conservation in SHM

    I first got the velocity of the combined mass with conservation of momentum and as it was in the mean position the velocity can be written as v = wA ( w= angular frequency , A = amplitude ) as we have to take it back to natural length i put A as the initial extension but i am getting a wrong ans...
  19. Achintya

    Sporting Goods for Outdoor Adventurers

  20. nuclearfireball_42

    Can I determine the phase angle of this equation by using the sin function?

    I've got the answer for (a). It's k = 0.78 N/m. I'm having problems with (b). I know that the equation of displacement in this case should either be : x(t) = Asin(ωt + φ) or x(t) = Acos(ωt - φ) where A = amplitude From what I understand, both the equation above should give the same result...
  21. N

    Solving for λ, a, and Vmax: An Analysis of Energy Balance and SHM

    a) λ = 4/3 by considering the energy balance as P moves from A (2a) to B (1/2a). The E.E. at A changes into a gain in gravitational potential energy + build up of E.E. at B since the spring compresses. b) a = 5/3g by considering that the mass P is in dynamic equilibrium immediately after...
  22. B

    Conditions for SHM question

    Ok so here are a few multiple choice questions that I have been given to me and these are what my selected options turned out to be Do they seem right? I am rather confused on the wording of the first question? Is it asking to state the conditions of SHM for it be in SHM? I know...
  23. B

    Working out velocity of particle moving in SHM

    So the way I have gone about it is to assume that the equilibrium position is half way between the 2 end points, hence the amplitude of this motion is 9.3/2 = 4.65 cm Therefore the displacement of the particle when it is 2cm away from one end point should be the distance between that point and...
  24. Beelzedad

    How to know whether motion is simple harmonic motion or not?

    I am reading "Coulomb and the evolution of physics and engineering in eighteenth-century France". There it is said in page 152 para 1 that "Coulomb found that within a very wide range, the torsion device oscillated in SHM". My questions are: (1) By just looking at the time period of the...
  25. Prabs3257

    Change in the time period of a pendulum

    I tried taking log and then diffrentiate the standard equation for time period of a pendulum but i am not getting the correct answer
  26. Vivek98phyboy

    Find the point of separation in SHM

    In the given problem, i can understand that after placing the two blocks in equilibrium it oscillates with an amplitude of The answer for (b) is given as To my knowledge, m2 separate from m1 when the acceleration is greater than gsinø and so they should be separating only at max displacement...
  27. Vivek98phyboy

    I Why is this SHM the way it is?

    I know four different forms in which an SHM can be represented after solving the differential and taking the superposition acos(wt+Ø) asin(wt+Ø) acos(wt-Ø) asin(wt-Ø) where a- amplitude In the above image they took B as negative in order to arrive at acos(wt+e). If i already knew i wanted...
  28. Saptarshi Sarkar

    Amplitude of oscillation for SHM

    From the first part of the question, I was able to get the value of ω which will be the same for the next SHM. But, I am having difficulties solving for the amplitude as I can't find the boundary conditions required to get the amplitude.
  29. G

    Analysis of SHM of a mass

    Could I please ask for views on this question: I've answered the whole thing and agree with the answers given in the textbook. Here are those answers (where Y is the modulus of elasticity of the string = lamda in the question): Period of motion = 2 * PI * sqrt( ma/Y ) Speed passing through...
  30. E

    B Determining ansatz for forced oscillations in SHM

    I've generally solved introductory second order differential equations the 'normal' way; that is, using the auxiliary equation, and if it is inhomogeneous looking at the complementary function as well, and so on. I know that sometimes it can be helpful to propose an ansatz and substitute it...
  31. jisbon

    Simple harmonic motion -- manipulating SHM equations

    My workings: ##D(t) = Asin\omega t## ##v(t) = \frac{\text{dD}}{\text{dt}}=Acos(\omega t)\omega## ##v(t) =Acos(\omega t)\omega## When displacement half of amplitude, ## Asin\omega t## = 0.5##A## ## sin\omega t## = 0.5 ##v(t) =Acos(\omega t)\omega## ##v(t) =\omega (0.5Asin\omega t)cos \omega t ##...
  32. warhammer

    B Shifting of a Cosine Curve with negative phase angle values

    Continuing on from the summary, the chapter has given a graphed example. We are shown a regular cosine wave with phase angle 0 and another with phase angle (-Pi/4) in order to illustrate that the second curve is shifted rightward to the regular cosine curve because of the negative value. Now, my...
  33. Shivang kohlii

    Shm , calculation of amplitude of spring mass system

    Homework Statement In A spring mass system , the spring stretches 2 cm from its 's frelength when a force of 10 N is applied . This spring is stretched 10 cm from it's free length , when a body of mass m = 2 kg is attached to it and released from rest at time t = 0 . Find the A) force constant...
  34. Shivang kohlii

    Equation of shm for different positions

    Homework Statement Write the equation for a particle in simple harmonic motion with amplitude a and angular frequency w considering all distances from one extreme position and time when it is at other extreme end. Homework Equations X = A sin (wt + ∆) ∆ = phase difference The Attempt at a...
  35. Celso

    Simple harmonic motion interpretation problem

    I'm in trouble trying to understand the expression ##t= \frac{1}{\omega} cos^{-1}(x/A)## that comes from ##x = Acos(\omega t)##, in which ##A## is the amplitude, ##t## is time and ##x## is displacement. When ##x = 0##, ##t = \frac{\pi}{2\omega} ##, shouldn't it be 0 since there was no movement?
  36. R

    Why is my thinking incorrect? -- Block and spring driven by a motor

    Homework Statement An oscillator consists of a block attached to a spring (k=400n/m). At some time t, the position (from equilibrium), velocity, and acceleration of the block are x= .100m, v= -13.6m/s, a= -123m/s^2. What is the frequency? mass of block? amplitude. Homework Equations position...
  37. J

    Why Does Acceleration Decrease When Velocity Increases in SHM?

    When a mass is in SHM, and is moving towards equilibrium point, its velocity starts to increase but why does acceleration decreases? What is the gradient when velocity is increasing and when it is at maximum? Thanks a lot!
  38. AgNO3

    Find the magnitude of this velocity - SHM problem

    Homework Statement Two rubber pads are affixed at the bottom of a box and the assembly thus formed is placed on a uniform slope of inclination 0.5 degrees. Coeff of friction is 0.60 between the pads and the plane. Two electric motors installed in the box can make the pads move back and forth...
  39. M

    Does amplitude depend on mass in SHM?

    Homework Statement Does amplitude of an oscillating spring with an attached block depend on the block's mass? Assuming the spring has spring constant 'k' and obeys Hooke's law. How would the amplitude of the oscillating spring system be affected if the mass of the block were...
  40. Shivang kohlii

    Amplitude of a mass joined to a spring in the presence of an E-field

    Homework Statement A block of mass m having charge q placed on smooth horizontal table and is connected to a wall thorough an unstretched spring of constant k . A horizontal electric field E parallel to spring is switched on. Find the ampliture of the shm by the block. Homework Equations kx=...
  41. Salman Ali

    Which of the options describes the phase constant for SHM?

    The only thing I know is that phase constant tells how much a signal is shifted along the x-axis. The answer of the question is both option a and b. I am not getting it!
  42. G

    SHM mass spring solutions

    Hi community, I've been looking at solutions for mass spring shm (undamped for now) ie that x = Acoswt and x = Bcoswt work as solutions for dx2/dt2 = -(k/m)x and that the general solution is the sum of these that with a trig identity can be written as x = C Cos(wt - φ) where C is...
  43. komarxian

    SHM: Planet Problem Homework Statement

    Homework Statement You are exploring a newly discovered planet. The radius of the planet is 7.20 * 107 m. You suspend a lead weight from the lower end of a light string that is 4.00 m long and has mass 0.0280 kg. You measure that it takes 0.0685 s for a transverse pulse to travel from the...
  44. velvetmist

    I Why is x=e^(rt) in SHM?

    This may be a fool question, but i can't figure where does this come from. I would really appreciate if someone can help me. Thanks.
  45. thebosonbreaker

    Simple Harmonic Motion: why sin(wt) instead of sin(t)?

    Hello, I have recently been introduced to the topic of simple harmonic motion for the first time (I'm currently an A-level physics student). I feel that I have understood the fundamental ideas behind SHM very well. However, I have one question which has been bugging me and I can't seem to find a...
  46. Vinicius

    Proof Acceleration in SHM - Get Help Now!

    Hello guys! Today I was studying SHM and I can't understand how to proof that a = -ω2Acos(ωt+φ) gives me accelaration of particle executing simple harmonic motion! If someone "build" this equation step-by-step I would be really thankfull! :)
  47. Mr Davis 97

    I SHM and the sign of k

    I have the equation for simple harmonic motion ##\displaystyle \frac{d^2x}{dx^2} + k^2 x = 0##. I have a simple question. Do we need to make an assumption about the sign of ##k## before we solve this? We have that the roots satisfy ##r^2=-k^2##. So ##r=\pm i \sqrt{k^2}##. Do I need to assume...
  48. B

    Derivation of resonant frequency for SHM systems

    Homework Statement My question here isn't a specific question that has been given for homework, but a more general one. For an assignment I have to 'derive an expression for the resonant frequency, ω0' for two different systems, the first for 'a mass M connected to rigid walls via two springs'...
  49. G

    The phase of a simple harmonic motion

    Homework Statement How can I calculate the initial phase in a simple harmonic motion if I only have the amplitude, frequency and angular velocity as data? Homework Equations The formula of the position, in fact they ask me to do the formula that allows to know the elongation depending on the...
  50. Ari

    How to find period of a SHM concerning a cube and spring?

    1. Homework Statement The 4.00 kg cube in the figure has edge lengths d = 8.00 cm and is mounted on an axle through its center. A spring ( k = 1400 N/m ) connects the cube's upper corner to a rigid wall. Initially the spring is at its rest length. If the cube is rotated 4.00° and released, what...