Beam Definition and 1000 Threads

A Gaussian beam has an intensity I(r,z), if the beam area at position Z is given by A(Z), then the beam gets focused by a lens of focal length f, what will the area of the beam be at the beam waist A(0) be? So I have been trying to figure this out for ages, I had to replicate an experiment in...

Homework Statement In the experiment of Davisson and Germer (a) show that the second- and third-orderdiffracted beams cannot occur and (b) find the angle at which the first-order diffracted beamwould occur if the accelerating potential were changed from 54 to 60 V. (c) What...

Hi, normally when we try to analyse a structural beam with composite section, we apply transformed section method or so. But what if two beams are just put together (one onto another one) instead of having a composite relation (e.g. glued together), how am I going to analyse the forces and...

What is the intensity in W/m² of a laser beam used to burn away cancerous tissue that, when 94.0% absorbed, puts 539 J of energy into a circular spot 2.11 mm in diameter in 4.00 s?? I've tried a couple different equations and I keep getting the answer wrong. This is due tonight, I'm super...

I am trying to make a FBD for equipment which is half out of the beam, I realize I can represent it with a single line of force. But how if I want to go for distribute load? which one is the correct one. (purposely not drawing reaction force on floor.)...

I think I am in a misconception concerning laser beams: Even the best lasers have a small line width. The spectral line is gauss-shaped. therefore the wave in position-pace is also a gauss-shaped wave packet, that travels with a certain group velocity. But this gauss shaped wave packet has a...

Homework Statement A beam of wavelength 600 nm has initially an intensity profile of Gaussian shape with a fwhm of 1 mm. Determine the intensity profile and fwhm 10 meter away.Homework Equations FWHM = λ/(2NA√(1 + I/Is)) The Attempt at a Solution [/B] FWHM1 = 1mm = 600 nm/(2NA√(1 + I/Is))...

regarding this equation, δ=(PL^3 )/(48EI) For the calculation of maximum deflection, if my structure is not longer a full form beam (meaning the structure has 6 holes drilled to it), can this formula still be used?is...

Bonjouro! Firstly, as this is my first post here, I would like to say thank you to everyone who is a part of the site and Hello! I've used this forum a number of times, but this is the first time I've posted here as this user! If the flexural stiffness of a beam is 25 MNm^2, and the beam is...

Hey guys, I am developing an program for calculation of reactions in a "4 point support beam". The problem is that this structure is Statically indeterminate and hence requires some other method. Support on any level is appreciated, especially from Civil Engineers. I will keep on posting...

G'Day Everybody, I am computing buckling of a rectangular(edges: a*b) specially orthotropic composite plate. The boundary conditions are clamped-clamped at the opposing loaded edges and the other two edges are free (also known as CFCF). After having the boundary conditions and the governing...

Hello, Can anyone help me find the boundary conditions of the below given beam please. Its a clamped-free beam but the overhanging sectiona and the mass makes it confusing. Actually I am puzzled about finding the initial conditions.

I tried to work backwards and verify the magnetic field required by the LHC beam pipes. A circumference of 27km implies a radius R=4300 m. The beam energy E is 7 TeV per proton beam. Considering approximation E approximately equal to pc to get momentum (ultra-relativistic case). Plugging into...

Homework Statement The mirror in the image below deflects a horizontal laser by angle θ. What is the angle φ if θ = 60°. Homework Equations θi=θr The Attempt at a Solution So I know that, if I draw a line normal to the mirror, that will make it so that the incident angle and the reflected...

Hello guys, I have a simple question about the max bending stress in a beam. We know that in a cantilever beam, the biggest moment occurs at the wall. This is also the location of the max stress with equation stress= M*y/I , However, in a simple supported beam, we have This time, the max...

1.Hey guys! I will need to design a floor with slab, beams and columns. Brickwall should rest on top of beam as possible. How about low wall, does it needs to rest on top of beams as well? Thanks! 2. No equation 3. I've designed some, but without low wall, that's what made me curious...

Homework Statement I attached the full document, buy I just want to know about : "Using calibration procedure determine: a) Sensitivity (mV/gr) b) Overall instrument error (gr) c) Linearity error %FSO d) Hysteresis error %FSO e) Precision error %FSO" Homework EquationsThe Attempt at a...

Hey guys, So just completed a question on a sign post subject to wind loading of 2 kPa where you had to determine bending moments across x and z planes (picture below), to determine normal, shear, max stresses and then determine the factor of safety depending on the beam type you chose. That's...

Hi I want to calculate the necessary incident polarization of a light beam at a given angle of incidence (theta_i) that reflects off BK7 glass (n = 1.5168) and is linearly polarized (i.e., 45 degrees). I know how to do similar calculations for incident natural unpolarized light, but not in the...

Compute the force exerted on the palm of you hand by the beam from a 1.0W flashlight. (a) if your hand absorbs the light, and (b) if the light reflects from your hand. What would the mass of the particle that exerts that same force in each case would be if you hold it at Earth's surface? On...

I've drawn the free-body diagram of an airplane wing spar. I know the magnitude and location of all forces. What is the procedure to construct the bending moment diagram?

Homework Statement Working out deflections on a semi circular bar. Homework Equations 3WR^3π / 2EI Where E = 200GN/m^2 W = 9.81N R = 150mm I = 5.625 * 10^-3 (bar is 25mm * 3mm) The Attempt at a Solution (3)(9.81)(0.15)^3π / (2)(200*10^3)(5.625 * 10^-3) = 13868.56 I have data that says it...

how to solve the large deflection of the beam, i have tried using finite element method but unable to find it.

For this we need a thought experiment: imagine you're on a gedanken planet manning a gedanken laser cannon, and it's pointing straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now let's keep you safe in a bubble of artistic licence, and...

Homework Statement A 7.20m long rigid beam with a mass of 105.9kg is supported at each end. A 64.8kg student stands 1.33m from support 1. How much upward force does each support exert on the beam? (Enter your answer for support 1 first, followed by your answer for support 2.) Incorrect. Tries...

Hi, I am trying to mathematically model the rotation of a rotary flexible beam. There are numerous papers which study this topic but all of them are considering the beam as a fixed-free one. My case is different. This is the beam I am trying to model. The motor axis is at the square portion...

1. Homework Statement Express the beam energy loss in the accelerator in terms of the change in the beam momentum. It is taken from one paper, where \begin{equation} \Delta T = \left( \frac{1+\gamma}{\gamma}\right) \frac{T_0 \Delta p}{p_0} \end{equation}expression is used for transition from...

To give a little idea for what I'm aiming for: I want to make a prop laser gun. It doesn't have to actually do anything, but I've decided it'd be awesome if it did. I could use a 2-5W blue laser diode like some people who make awesome contraptions with lasers show on YouTube, but I'd frankly...

Homework Statement Two beams of different cross sectional areas are fused together to create a single beam, as shown in the figure above. The following relationships apply: A1 = 2A2, L2 = 2L1, E1 = 3E2. A tensile force F is applied at the ends of the bar, as shown. What is the ratio of the...

Is it possible to create a cantilever beam with constant or increasing stiffness. I've been experimenting with several different shapes and profiles, and have not had any luck. I know that there are shapes with constant stress throughout, but I'm hoping to find a shape with constant or...

Do you guys know a low-cost low-threshold optical beam limiter, with cost somewhere ~$100. Or if you know certain method to fabricate such. I would be greatful if you could include links and/or references. I am still noob in photonics so I am only familiar with a beam limiter that blocks the...

Can electrons be "guided" or "carried" by a beam of light, something in the manner of how a ship can be guided by a current? So suppose we emit a uniform field of electrons. I don't know if field is the right word. I mean a bunch of electrons of more or less uniform distribution are being...

The problem is attached.

Hello Is it possible to derive the Euler–Bernoulli equation: \frac{d^2}{dx^2} \left(EI \frac{d^2w}{dx^2} \right) = q from Navier-Cauchy equations: \left( \lambda + \mu \right)\nabla\left(\nabla \cdot \textbf{u} \right) + \mu \nabla^2\textbf{u} + \textbf{F} = 0 I don't really know where to...

Hello I am trying to setup a problem to represent a pipeline crossing over another perpendicular pipeline on the seabed. I am trying to represent the problem as a simple beam and having some issues with the supports i am selecting and the boundary conditions. Attached is a picture representing...

Hi guys, Hopefully a fairly simple question. All beam formulas I've come across, whether in my own textbooks or Machinery's Handbook, have two sets of formulas for beams. One will be for "simply supported", where one end is pinned and the other end is a pin-roller. The other connection type is...

How would one go about making a particle beam cutter? I'm thinking like a powerful laser type cutter. Please no mechanical engineers, I want a purely physics point of view.

How would someone go about to make a phased particle energy beam? What are the physics behind it? Any research that anyone knows on the subject that I could take a look at? Thanks

Hey all, I want to calculate the stress and strain on a beam using MATLAB and I would also like to make a stress-strain curve as well. The problem is as follows: I have a hollow rectangular aluminum beam that is fixed at both ends. I have the material properties and the dimensions of the beam...

Homework Statement Homework Equations FBD and all forces and moments = 0 The Attempt at a Solution Sketched in the image. So, I don't know how to go on with my analysis of the load, since I can't determine the reaction forces. Can someone please help me? Thanks in advance!

Homework Statement I just don't understand how to set the problem for the free body diagram (point (a) and (b)). Can someone help me with this problem? Thank you in advance.

I posted a question about Rabi frequency here https://www.physicsforums.com/threads/what-is-rabi-frequency.331082/ some times ago. The replies there answer some of my questions but I am still looking for detail explanation on the relation between Rabi frequency and the power of the beam. I read...

Hello, I can't find the formula for bending moment calculation of continuous tapered beam. the cross section is I (H) form, where web is 179.5 cm flange is 67 cm, web thickness is 1.5 cm and flange thickness is 2.5 cm. And this beam changes its height to 89.7 cm all other dimensions is the...

Homework Statement A uniform meter stick of mass M is pivoted on a hinge at one end and held horizontal by a spring with spring constant k attached at the other end. If the stick oscillates up and down slightly, what is its frequency? [Hint: Write a torque equation about the hinge.] The length...

Please refer to the following image, which shows a portion of the deformed centerline of a beam in its equilibrium configuration with a uniformly distributed load. The stress resultants are the axial forces T, transverse shears Q, and bending moments M at sections 1 and 2, with the rotations...

what is the formula for the cantilever beam having two different young's modulas and moment of inertia, when a point load is acting on the free end. i have been trying but unable to get the formula. if the formula i can validate my project work and complete it

Homework Statement Homework Equations ΣF=0 ΣM=0 The Attempt at a Solution I think i correctly identified two 2 force members at A and B. But would the system be a 3 force member? If it is i don't quite know how to solve for the missing angles. Is the problem asking for the sum of the...

Homework Statement I have a 100cm beam with the fulcrum at the 20cm point. At the 0cm point is 300g which puts the beam into balance. Homework Equations How can I find the total weight of the beam and the torque due to the weight of beam using the given information.The Attempt at a...

So for sake of example the LHC beam one pointing at the other to cause a collision, the one beam is 6.5 TeV per beam. How can I calculate the volts per meter or given size of pulse? I understand that the particles have kinetic energy in the form of the speed of their travel but theoretically...

Could a particle(proton, gold ion, electron) beam reach the surface of the moon, given current technology? Would the beam diffuse too much too scenter the regolith? Or would the beam have to be focused or continually refocused in order to achieve that? If so why can they do it with laser...