Materials Definition and 919 Threads

Why would the force P not always be equal to 60 kips? (I mean, since the structure is in equilibrium, and the members are rigid, can't we shift the two forces of 30kips each to the line of action of force P and conclude that P is always 60kips?) Thanks for your time.

Homework Statement (please see the attachment) Homework Equations σ=F/A The Attempt at a Solution I just can't figure out how to find the forces in the two members. Actually I thought the force in both members will be the same, but according to the problem statement it clearly...

I've been doing some research on majors and have narrowed my interests down to something involving a mixture of chemistry and math, possibly physics as well. From what I have found Chemical Engineering and Materials Science and Engineering seem to be closest to my ideal mix, though the...

Hi everyone, I've taken a course at uni that may be a little bit over my head, and am pushing through an assignment for it at the moment in an attempt to do well. I've hit a bit of a roadblock on one question though, so am hoping that someone kind here can help me out! The question is...

I need to find an equation to figure out the breakdown voltage of layers of materials. In my case it will be air then glass then an inert gas. Any one have any info on how to get this. Thanks.

no its not a homework question it was in a quiz but i believe the teacher is wrong about it materials are heated when they absorb: -electromagnetic radiation of any type -infrared radiation only -microwaves and infrared only please choose and explain Thanks in advance

Dear Physics Forum, I posted this in the Mechanical Engineering Forum a while ago without any responses, but by looking at the other threads I suspect that it was the wrong place so I am posting it again here where it looks more at home (so apologies if i was wrong!). Can anyone explain...

So I have been reading up on composite materials and have been geting a bit confused, from what I have read, composite materials consist of a matrix and reinforcement, the reinforcement can be fibers, I read that the way the fibres are placed will effect the machanical properties of the material...

I'm currently in university and am taking supplemental math classes for an engineering major. I am currently undecided which engineering path to chose to major in as of yet. Materials engineering caught my eye and I just want to know some examples to work that materials engineers do. I have read...

[b]1. The equilibrium bond length r0 in ion components (or salts) can always be obtained from the tabulated values of cationic, r+, and anionic radii, r-, respectively as r0=r+ + r- Show how on this basis, and that above (refering to the first part of the problem where i was to verify that...

Hey guys, back again for some help if that's okay! I've derived a formula for an electromagnetic wave entering a material, as \underline{E}e^{-\frac{x}{\delta}}e^{i(\frac{x}{\delta}- \omega t)} x=direction of propagation t=time \delta=skin depth As you can see this describes the wave...

I have a scientific background in materials science. However this is one type of material that we don't exactly learn about! Let's say you have a neutron star approaching a comparable mass black hole. As the neutron star approaches the event horizon for such a comparable black hole, tidal...

Over the past few weeks I've undergone a few operations. I had a root canal, crown lengthening and filling. Throughout these procedures loads of various chemicals and materials were put in my mouth. Many times I think some got swallowed or at least eventually leak into my system. Are these...

New here, sorry if I'm in the wrong place or unclear, etc. I've been looking at torsion on solid plates and the torsion constant. I was wondering how to handle the torsion constant on a plate of changing cross section (e.g. there are holes drilled in it, changing the area of the cross section...

Hello all! I chose not to follow the given format, as my question is kind of unique. I hate to be one of those people who just create an account for one thread (as I usually try to avoid this), but my situation is quite urgent. I have a project due Friday, in which I plan to take different...

This is a future project, but I want to have everything once the weather warms up. Also, if this is in the wrong spot, please move it. The Plan: In the early summer I plan on going on a mini tour and would be camping along the way. I will use a tarp that's big enough to use as a pup tent and...

Hi everyone, I have been trying to find some materials that could be used for very high temperature piping but have been struggling quite a lot. I have been looking at stainless steel alloys mostly. The specs are really tough: 1200 celcius of helium at 80MPa. My main concern here is...

Hi and thanks for helping me with these physics questions. Firstly, will a magnetic field pass through non magnetic materials as though it was air? For example, will a magnet still attract another magnet when copper or wood is placed in between it? I understand that if the material in...

Hi, I just signed up with the forum. I have a degree in Mechanical Design, have been working as a drafter. It's been about 10 years since I've done any statics and wanted to re-learn this stuff by making a bucket loader for my garden tractor. The last few months I've been reading my...

Lets assume that all properties of a piece of piezoelectrical material are known, how should the analytical calculations be performed if the goal is to convert a vibration into electrical energy? What I'm looking for is the theoretical output voltage one can achieve for a known vibration. To...

I recently sent in my application for the materials engineering program at McGill University. I was all set on this career path but doubt is beginning to set in. Friends and family have been telling me that materials engineering is a dead-end, that the jobs are few, and growth minuscule. They...

Hello, I am reading a fabulous (though somewhat older book) called "Intelligent life in the Universe" by s. Sagan and I.S. Shklovskii. They describe intense magnetic fields extending from the galactic core that channel interstellar gas and dust into the spiral arms which are the primary site...

Anyone know where I can get a list of different core materials and their permeabilities?

Could someone please check this for me? I attached a rough free body diagram of the whole frame. Any help is appreciated. Homework Statement The member ACF of the frame loaded as shown is connected to member BCD by means of a smooth peg and slot C with force P = 930 N at point D...

Homework Statement Calculate the R-value of the stack of materials whose total thickness is made up of the individual thicknesses: material 1; k = 0.123 W/m/K, thickness = 0.103 m material 2: k = 0.234 W/m/K, thickness = 0.092 m material 3: k = 0.345 W/m/K, thickness = 0.081 mHence...

hi.. please tell me that 1) why some materials like ZnO, SnO, Pt, etc r sensitive to gases and others like Si, Ge, InP, GaAs, etc r not sensitive to gases. 2) how doping increase the sensitivity of a certain material to certain gases.

As far as I am aware, Rare Earths and particularly NdBFe is the strongest known magnetic material. Is this true and what is the strongest magnetic material known that it is in common use and what is possible theoretically? Thank you.

Hello everyone, Recently I have been studying cavity resonators. I noticed that all cavity resonators have air in them, but I was wondering what the effects would be if something other than air was used? For the sake of simplicity let's say we put a dielectric material in it with a...

If you are a student, or a budding entrepreneur, your R&D budget may be limited. But it is during this time that getting your hands on material is most important! I've had some success with (what is basically) e-begging so I'm sharing my strategies with anyone that can make use of them 1)...

Homework Statement http://img820.imageshack.us/img820/3373/torsionquestion.jpg Homework Equations (In the solution) The Attempt at a Solution I got M(max) and d correct. I can't get the angle. But I'm using the formula exactly as is. What's wrong...

Homework Statement http://img840.imageshack.us/img840/736/mmaterials.jpg Homework Equations http://img18.imageshack.us/img18/8739/releq.jpg The Attempt at a Solution http://img845.imageshack.us/img845/7017/pitul.jpg The answers turn up (a) 56.6 MPa and (b) 36.6 MPa so I'm...

[FONT="Comic Sans MS"][SIZE="3"]Problem A vertical oscillating system consist of three equal springs with elasticity coefficient c , among which a mass m=2kg is suspended.The system oscillates according to the following law of motion x(t)=0,4 cos 4t+0,5 sin 4t , (m) . Determine: 1) The...

Why are optical traps constructed using beads that are made of dielectric materials? What property of dielectrics is being employed here? Would a non-dielectric material still experience radiation force from photons? Thanks!

Ok, I am looking over stuff for an exam. I am a bit confused on something. When conductivity is zero, a medium is lossless. Zero conductivity means infinite resistance. For infinite resistance, no electrons will flow, but an electric field can propagate forever. A wire has high conductivity, so...

Homework Statement http://img62.imageshack.us/img62/9815/mechmatt.jpg P = 235 kN d = 50mm (diameter of the axis) t = 20 mm t1 = 12 mm Safety coeffecient = 2.0 σy = 320 MPa Check the axis for strength (shear and compression) Homework Equations...

Hello! I was wondering, why X-Rays can go through some materials, such as skin, whereas light from the visible spectrum cannot go through these(although holding a flashlight to your hand does create a red glow). Likewise, why are X-Rays stopped at the bone, and not the skin? Lastly, why does...

I'm trying to search for information relating to friction and a surface with different parts made of different materials. For example, a plastic box is attached to a wooden box and slid down a track. If we were to switch how the plastic and wood was distributed on the surface, e.g. by...

Hi guys, I'm a first-semester junior seeking some quality study resources relevant to the physics GRE. I've heard that ETS has released a few exams from past years... Where (if anywhere) can I find the previous exams in some reasonable format, like PDF? The best I can find is this website...

Many materials, such as paper and cloth, are transparent when wet. Of course I understand that water is transparent, but why does a non-transparent material become transparent when something is _added_ to it? If there is some material that blocks the path of the photons, how does adding yet...

Homework Statement Homework Equations The Attempt at a Solution I was attempting to solve this exercise, but since I have no answers, I have no way of knowing if it's correct. Any help Is more than appreciated

Hi, mirrors are made by coating glass with tin and then silver. I was wondering whether it would be possible to coat other materials with silver e.g. fibreglass? Assuming of course that an appropriate smooth finish could be achieved that would produce a mirror like finish in the end.

Hello, When neutrons hit materials, it can cause them to degrade and crack. The way this is measured is in displacements per atom. The equation for this effect is the following: Displacements per atom = neutron flux * time * materials cross section (@ that neutron energy) Cracks...

all i can find on the internet are the attractive and repulsive forces between 2 magnets... where can i find the relationship between distance and attractive force , between a magnet and i.e. a piece of iron?

Hi Do any of you know any good websites on bio inspired materials? I have tried to do a search but only random sites that are not related to it comes up?

Hello, I thought hydrophobic materials are materials which repel water? How will they help in removing oil from water? Thank you

are superconductors dia magnetic materials?? if so, what are similarities between them??

Hi all, I'm a student studying transportation design at university and I've been given a project where i need to design a lightweight family vehicle. We've been told to especially look deep into new materials that are lighter than the materials currently in use that don't compromise the safety...

Homework Statement http://img85.imageshack.us/img85/6346/missrd.jpg Across the axis of a steel rod act 3 forces: F1 = 80 kN F2 = 50 kN F3 = 30 kN Crossection area of rod = 4cm2 What are the forces that are being made a the different parts of the rod, and what will be it's overall...

Homework Statement A hollow shaft has torque being applied on both sides. The angle of twist is 50 degrees, the diameter is 100 mm, the thickness t has 5 mm. We are given that the allowable stress is 120 MPa, and the allowable shear stress is 50 MPa. We are asked to solve for the...

If water is hold inside the water bottle, which is made of plastic, and I play music within the room, can the sound vibration get through the plastic bottle and transfer it into water? Does anyone have any suggestions on what kind of materials to hold the water to get the best transfer rate on...