Beam Definition and 1000 Threads

Homework Statement Assume a Gaussian laser beam ( 1064 nm wavelength) having an FWHM-diameter(intensity) of 5 mm. By transmission through a thin nonlinear crystal, a new wave is generated that is proportional to the square of the incoming field (and therefore radiates at twice the frequency, or...

Homework Statement In the example , I suspect the selected A (area) is wrong... From the notes , A' is the area of top (or bottom ) portion of the member cross sectional area . But , in the example , we could see that the selected area is located to the right of the point where shear stress is...

Hello PF, I am trying to analyze a a beam, connected to another beam at one side at multiple locations (bad quality drawing below). The top side of the beam extends further and sit on another beam, while the shorter lower side is directly connected to another beam. They are all bolted...

Homework Statement In this notes , why the shear force used is the 19.5kN ? Why not 6.5kN ? From what i know , the formula of shear stress is tau = VQ/ It , where V is the shear force ... There are two values of V in this question , why the larger one (19.5kN ) is chosen ?Homework EquationsThe...

Homework Statement I have an evenly distributed load with overhang and symmetry. I want to express the reaction loads as a function of support distances. I did the the 3 support problem with integrating a load structure and redundant and solving for the center reaction to find the outter...

A cantilever beam at low frequency behaves like an underdamped 1 DOF mass/spring/damper system. We are trying to find the roots of the Characteristic equation which are lambda1,2 = -dampingRatio x wnatural /sqrt(1-dampingRatio) Relevant formulas and given values: damping ratio = c/2sqrt(m/k)...

Homework Statement I am given this beam: imgur link: http://i.imgur.com/tw6EEJz.jpg and asked to express the slope at A and the max deflection in terms of a, E, I, and Mo. I am being told that my answer has the wrong multiplier...so I assume that my overall approach is ok (??) but I've...

If I shine a laser beam through a calcite crystal, the beam is split in two, as shown below. Are the photons in the split beams in an entangled state?

Homework Statement Why we need to replace the 10kip load at 2ft from D to D ? Homework EquationsThe Attempt at a Solution IMO it's wrong ... There's no need to do that .

Consider the case in which an incoming particle collides with stationary target particle producing new particles through the interaction. For example, $$e^{-}+e^{+}\rightarrow X+\bar{X}$$ My question is, why in general do the particles produced in such an interaction propagate outwards are...

Can a beam of light be objectively in a specific photon number state (Fock state), let's say ##|2\rangle##? Or is it (the specification of the state) detector/observer dependent? I.e. we can only say that a beam of light is in a Fock state, but which exactly is detector dependent (detection time...

Homework Statement In an inertial reference frame, a beam of light is shone 30 degrees from the x-axis. What is the speed of another inertial reference frame along the x-axis where the beam of light is 90 degrees from the x-axis? Homework Equations Can't really think of any equations that...

Homework Statement Just having some trouble with a question about Fabry-Perot intereferometers. Here's the question: a) Consider a beam of light undergoing multiple reflections in a Fabry-Perot cavity between two surfaces, both with reflectance R, and with no absorption. Homework Equations...

Hi, I'm trying to calculate bending stress for a cylindrical beam. I'd like to have my result double checked because I got an answer that doesn't make sense to me. All of this is personal research, so I'm not very confident in my answer. It's a cantilever beam with a point mass of 347.4 oz. on...

Homework Statement A photon beam is incident on a proton target (at rest). Particle X (and nothing else) with rest mass M=1.232GeV/c2 is then produced. Use m_p =0.938GeV/c2 as the proton mass. a) What is the energy of the photon beam, in terms of GeV? b) What is the momentum of the moving...

if a coherent laser beam rotates about an axis at very high angular frequency can a light dot with radiant glow (of short radius) be obtained due to persistence of vision ?

Would it be a drop in power as the square of the distance in a directed microwave beam? Thanks!

Homework Statement For the y-y axis buckling , the beam will bend towards either positive or negative y-axis , right ? I don't understand that why for y-y axis buckling , moment of inertia (Iy) about y-axis is used ? Homework EquationsThe Attempt at a Solution IMO , it's wrong ... When the...

To give a bit of context, I am doing my final year university project on micro-mechanical interactions between an AFM probe and a sample surface. I do not have notes for a system this complicated, as we always considered our systems to be rigid bodies. I was always relatively clueless at...

Homework Statement To give a bit of context, I am doing my final year university project on micro-mechanical interactions between an AFM probe and a sample surface. I do not have notes for a system this complicated, as we always considered our systems to be rigid bodies. I was always...

Hi there I have a general question. I understand the process of light through a optically denser material, slower speed etc... but why would a laser beam in oil be easier to "see" than a laser beam through water. Cheers

If the unbraced length of a beam is 3 m and the maximum bending moment in this unbraced segment is 312 kN-m, and also the maximum moment in the braced segment of the beam is 350 kN-m, select an economical section just based on the moment requirements. Use Table A.2M included in the course...

Homework Statement In this question, we are interested inthe buckling of column, so we should calculate the moment of inertia (Ixx) or (Iyy) at the column,right? Homework EquationsThe Attempt at a Solution Why the author calculate (Ixx) and (Iyy) using the cross sectional area of beam? is it...

Homework Statement in this question , ( in second photo) i don't understand that why at eccentricity ratio = 1 , P/ A is 83kPA , why the vertical line is drawn at a point between 100 and 150 KL/r to find P/A ? Homework EquationsThe Attempt at a Solution Is it wrong ? Or I left out something...

I have to calculate Airy's stress function for a cantilever beam made of two different material along its length. The young's modulus of the first half is E1 and E2 for second half. The beam is made such that these materials are joined to each other one after other along its length. At the...

Homework Statement I am trying to understand how forces transfer from a wheel / pulley onto a beam, and then calculating the resulting moment. The image describe the problem. The rope is in tension with force "S", the wheel/pulley can rotate freely without any friction. Homework Equations...

This is sort of SF in the sense that it's not scientifically accepted or reviewed. The "idea" comes from other people and it is that a usually round light beam of a certain diameter, like 30-50-100-similar cm diameter, extends slowly and even stops midair. It's flat at the end. Like a straight...

Can anyone help with calculating the starting and stopping torque required to rotate a uniformly laden beam with a total weight of 200kg around a fixed axis. The beam has a length of 2200mm and will be started from stationary, rotated through 70 degrees at which point it will stop and reverse...

Homework Statement where V = total shear force at the location in question; Q = statical moment of area; t = thickness in the material perpendicular to the shear; I = Moment of Inertia of the entire cross sectional area. based on this formula , the shear stress is max at the neutral axis of...

Homework Statement for the circled part, why the why the author didnt include -12(9)kNm moment in the equation of moment ? [PLAIN]http://imgur.com/a/l3Bu4http://imgur.com/a/l3Bu4 Homework EquationsThe Attempt at a Solution IMO, the author should include it in the equation, am i right? So, M=...

[mentor note: moved here from another forum, hence no homework template.] A construction worker attempts to lift a uniform beam off the floor and raise it to a vertical position. The beam is 3.00 m long and weighs 372 N. At a certain instant, the worker holds the beam momentarily at rest with...

I have a plate of 600mmX92mmx2mm. All the four sides are fixed.How can I calculate the effective deflection at the center due to self weight considering the deflection in longitudinal and transverse direction? Density of material 1170kg/m3 Modulus of elasticity 2.5GPa

Here I am only considering 4 adjacent electrons in electron beam, especially the 2 electrons that are moving in tandem with velocity v. Moving charge will generate circular magnetic current. you can imagine magnetic flux as current, just like electric current. So, the question is same to find...

Homework Statement I don't understand why the sign of moment of beam at left (clockwise) and moment at the right of beam (anticlockwise) are considered as positive... Why we can't assume the clockwise moment as positive and anticlockwise moment as negative? Homework EquationsThe Attempt at a...

Homework Statement in the first diagram , i notice that the moment is constant throughout the beam... why in the second notes, for the moment 20kNm at 2 ends of beam, why the moment varies from -20kNm to 0 from one end to another end? Homework EquationsThe Attempt at a Solution Which is...

Homework Statement http://www.mathalino.com/reviewer/mechanics-and-strength-of-materials/solution-to-problem-625-moment-diagrams-by-parts) from the link , why the distance of centroid from B is (4/3) and (9/4) as shown? Homework EquationsThe Attempt at a Solution it should be (4- (2/3) ) and...

Homework Statement for the first line of solution , i don't undertsand why the author only include one P/2 force only... Homework EquationsThe Attempt at a Solution I think it should be EIy" = 0.5Px -P(x-0.5L) -0.5P(L-x) , am i right?

Homework Statement In my notes , I was told that shear stress is maximum at the neutral axis . The normal stress will be maximum at one end , while the another end will be minimum... Homework EquationsThe Attempt at a Solution Why the shear stress is maximum at the neutral axis ? When we...

Homework Statement I have the bent beam like this . The inner part of beam undergo compression , right , so it shortens. Why the stress is minimum at here ? the outer part undergo tension , why the normal stress is maximum here ? This is from my notes http://imgur.com/a/H8fy4 Homework...

Hi all! I have to calculate the natural frequency of the system. Any idea of boundary conditions of this case? There is beam supported by two springs on the left side.

Homework Statement determine deflection of beam Homework EquationsThe Attempt at a Solution at x=0, y=0 , i found that C2 = LP(a^2)/6 (circled part) but the author gt 0, which is correct?

Homework Statement refer to the circled part , i don't understand the author's working . Homework EquationsThe Attempt at a Solution I think it should be 450x - 150(4-x) -30092)(x-1) , correct me if I'm wrong . (taking moment about x ) ...

Homework Statement can someone explain about the RHS of EIy' and EIy'' ? how to get the RHS of EIy" from RHS of EIy' ?? It's not integration of dx , am i right? Homework EquationsThe Attempt at a Solution if it's integration of dx, it should look like this , right?[/B] EIy' = 0.25P(x^2) -...

I am calculating the strain in a cantilever beam with a point load for a given deflection. The deflection is around .5mm for a beam that is just over 5mm long (width is 3.8mm and height is 0.15mm). I was told for the assumption of small deflections to be valid, deflection should be 2% of the...

Homework Statement A light ray falls from the air (##n_a=1##) into the center of the upper surface of a long cilindrical glass tube with an index of refraction ##n_t=3/2##. The tube is submerged into water all the way to the upper edge and the waters index of refraction is ##n_w=4/3##. What is...

I am trying to derive the strain at the base of a cantilever beam with a known deflection. I know the bending stress is equal to Mc/I, so the strain is Mc/IE, where c is the distance from the neutral axis. For a point load ,P, the strain would then be PL/IE. Since the deflection is known I...

I came to know that the PACS instrument of HERSHEL has a resolution of 5" at a scan speed of 20''/sec whereas it's 10'' at 60''/sec. The resolution has almost doubled with the scan speed. Can you please tell me why it's so?

What is the equation for how a light beam is bent by a mass? Say a mass M way out in space, and a light beam is aimed from VERY far away such that it should pass at a radius R from the mass.

Well, i have a cantilever beam where i have the displacement of the tip of the beam (y axis) data from a vibration of this beam. In the tip of the beam is a steel wire attached, pulling up the beam with an angle (30º for example). I want to know if exists a form to obtain the strain of the wire...

Hi, Well i have a system with a excited (in y axis) cantilever beam. I struggling to obtain a expression that gives the strain based on the dislocation y. I know that the displacement of the beam is given by: Ya=PL^3/(3EI) but how i make a correlation between this and the strain of the...