All Questions

0
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0answers
12 views

Frequency of radio to penetrate about 8 ft of saltwater

I am trying to penetrate about 8 ft of seawater with a radio wave. What frequencies will be able to penetrate this quantity of saltwater? I understand that low wavelengths penetrate seawater the best, ...
0
votes
0answers
3 views

How to prevent leakage radiation from a grid of inductors laying on a plane?

I am thinking of designing a large wireless charging pad/table.The idea is to have many inductors in a grid setup, where when a phone is placed on the pad/table it starts charging from the inductors ...
0
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0answers
14 views

What kind of physics do engineers use daily? [on hold]

I am interested in areas of physics engineers use daily.
0
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0answers
10 views

Where in the UK can i buy s stator for this small DC 3 phase motor that i damaged while trying to extract it

I was trying to remove a stator from the housing and damaged it , hence am trying to find a new one but cannot find anybody based in the UK that I can get "customisable dimensions" from and none of ...
0
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0answers
9 views

Static charge, PVC pipe and water

I know it's possible for a PVC pipe to develop a staic charge due to fluids flowing through them. This is a twist on that idea. Can a sealed length of pvc (say 3.5 feet in length) - tethered below ...
0
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0answers
9 views

Are there any books which show how to design electrical coil heat exchangers?

I need to design an electrically powered gas heater, but i need to do so in detail. I'm looking for a guide similar to the shell and tube heat exchanger design guide in coulson and richardson's ...
0
votes
1answer
15 views

What happens in a cone-shaped nozzle?

So I am learning for thermodynamics now and there is one thing that is bugging me. In the book it shows a laval nozzle (very simplified) and a diffuser. with the formulas: (a is the speed of sound) ...
0
votes
1answer
22 views

Push button design for small gadget

I'm looking at designing a small gadget (think something like a Fitbit in size) where the case has a couple of buttons on it. For various reasons the buttons have to be around the narrow side (edge) ...
0
votes
1answer
49 views

Is it OK for a 2 story house not have a column or pillar

sorry for my english. I was looking to buy a house. I saw some in my hometown, which is very affordable. but on a picture of the house they are selling I found on the net troubled me. no pillar/column,...
1
vote
1answer
32 views

Why are variations zero on the endpoints of a beam?

On Wikipedia derivation on Timoshenko beam equation we arrive at this: $$ \delta U = \int_L \left[-M_{xx}\frac{\partial (\delta\varphi)}{\partial x} + Q_{x}\left(-\delta\varphi + \frac{\partial (\...
1
vote
0answers
19 views

Why is pure shear a “shear”?

If one looks up the meaning of shear strain, most sources talk about this situation: That is, a force acts along a surface of an element at it is elongated, turning a rectangle into a rhombus. ...
0
votes
1answer
19 views

Question about AutoCad [on hold]

I found an image to draw in autocad, shown in the picture below. I wanted to know if someone knows where I can find similar problems to solve ( draw) in autocad ?
0
votes
1answer
44 views

What type of fastener is this?

Used to connect the chain for a window actuator to a U-shaped window bracket. The threaded end screws into a bolt hole (M5.5 female thread) on one side of the U-bracket. The tip of the fastener fits ...
1
vote
2answers
28 views

What is up with the spaced rudders on the SMX-31/Barracuda?

You can see it in the video here for the Barracuda: https://youtu.be/_NZKyvQVRd0?t=124 And here's a pic of the SMX-31: http://www.hisutton.com/images/Fr_SMX-31_cutaway.jpg What are the advantages ...
0
votes
0answers
28 views

Calculating Mass Fractions of a Hydrogen and Oxygen Gas Mixture Pre Ignition

I am trying to calculate mass fractions of a Hydrogen Oxygen gas mixture as a function of equivalence ratio before ignition. My work is the following: Equivalence Ratio: $$\phi=\frac{FA}{FA_s}=\frac{\...
-2
votes
0answers
32 views

How to find radius of curvature? [on hold]

How to solve for y=[x^3 *(1/20) -5]? it gives 0/0 for the radius at x=0 where dy/dx=3x^2 (1/20) d2y/dx2=6x(1/20) Thank you
0
votes
0answers
48 views

Interview question: A rectangular pinned sheet with PTC is heated on the bottom and cooled on top. What happens [on hold]

A rectangular sheet of metal, pinned at its edges, has a positive temperature coefficient (PTC). It is heated on the bottom and cooled on the top. What happens? I got asked this question in a ...
1
vote
1answer
16 views

Whats the correct name for the filament driving mechanism used in 3d printer extruders and MIG wire feeders?

Looking for the correct terminology to for the cable/filament feeding mechanism used in 3d printer filament feeder where the filament is gripped between a bearing and a gnarled gear tooth driven by ...
0
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0answers
26 views

What are the materials most transparent to microwaves?

I need to build special equipment for a microwave oven ( 2.45 (GHz)). But even glass and plastics do heat up in microwave ovens. Where can I find a list of the materials that are the most transparent ...
2
votes
2answers
37 views

Identifying Compression and Tension as well as Hogging

Im looking for clarification on how the solution identified the moment to be hogging, as well as the axial stress to be in compression? Also I'm confused as to how the solution came to a conclusion ...
-2
votes
0answers
14 views

Actually real Iron man suit [on hold]

What other people have done: Many people have had this idea. For example Adam Savage's newest video "How Adam Savage built a real Iron Man suit that flies" They used a laser beam to melt the liquid ...
1
vote
1answer
34 views

How is the stress concentration factor calculated in FEM?

I have written my own finite element code for a linear elastic (plane stress) problem consisting of a plate with a circular hole in the middle, fixed on one side, having a tensile force acting on the ...
0
votes
1answer
28 views

Max compression & Tension

I'm seeking an explanation in reference to the photo below. I'm unsure how the solution within the red box calculates the max tension of the Aluminium beam and the max compression off the Aluminium ...
0
votes
2answers
40 views

Ideal gas law, theory vs reality

I am trying to get an idea of the amount of hydrogen that I can store in some pressurized steel tanks underground. Based on the ideal gas law PV=nRT I did a simple calculation pressure = 200bar ...
2
votes
1answer
93 views

Max Tensile & Compressive Stress Question - Identify the equation

I'm struggling to identify which equation is used within the first red square. Could someone please help identify which equation was used as well as why? Thankyou!
-1
votes
0answers
15 views

heat transfer from flowing water in a tube to air

Currently I am doing a project on heat transfer .I have considered a system in which , there is a chamber with desired volume (1 m3 ).Air is filled inside the chamber at 5 bar and 35 degree Celsius ....
1
vote
2answers
32 views

Tempered glass physics

I have two related questions Why is a thicker tempered glass stronger than thinner? For example, I have to hit much harder at 3/4” tempered glass panel surface than I hit 1/4” panel in order for ...
-1
votes
0answers
9 views

material balance without chemical reaction [on hold]

the original text is in Portuguese. For the situation below, determine the composition of the final product stream when the following reaction occurs: CH4 + 2O2 ---> CO2 + 22H2O Please who solve ...
2
votes
1answer
31 views

How to analyze a bent beam: Stress concentration?

I am analyzing a beam, that has a bend in it. Intuitively and inspecting FEA results using a linear solver, there is a stress concentration at the bend of this I-beam. When I was learning about ...
1
vote
0answers
24 views

Shouldn't brittle materials be the ones failing under shear deformations?

It is known that brittle materials tend to fail under normal stresses, that is, tensile or compressive stresses. Brittle materials often are bound together into crystals by ionic bonds between atoms, ...
0
votes
0answers
9 views

Info concerning an old AC unit [migrated]

I have a Panasonic cu-g125ke ac unit which trips the curcuit breaker 30 seconds after its's powered on. I have searched the manuals for what to do but it says: contact a dealer in your area. The ...
1
vote
1answer
19 views

Why is deviatoric stress the one causing distortions?

I'm reading this text on stress. It is mentioned that the Cauchy stress tensor can be split into a sum of two other tensors: hydrostatic pressure $\pi$ and deviatoric stress. Hydrostatic pressure is ...
3
votes
0answers
19 views

Equation for the spring constant of an orthotropic, rectangular wire spring

I hope I can get some help with this problem as I've been struggling with it for a long time. I have a helical tension spring with radius $R$ and a square wire cross section and made of orthotropic ...
2
votes
0answers
19 views

How to find a dimension that isn't explicit if there are tolerances

For a part like the one shown, let's say I wanted to find the dimension labeled 3", if it wasn't already labeled. Since there are tolerances already on the part, how would I determine the 3" value ...
0
votes
1answer
22 views

How does polygonal effect affect the effect of angular synchronization in car engines' timing train drive?

Is a regular roller train drive used in most car engine's timing chain drive? If so, wouldn't the polygonal effect affect the accuracy of strict angular synchronization between the camshafts and the ...
-1
votes
1answer
28 views

How to calculate flow rate of water through a hole? [closed]

The hole will be 1" NPT connected to 3/4" diameter pipes and I want to know if a flow rate of 20 Gallons/Minute is possible for this configuration. Is it possible for me to solve this with the ...
-1
votes
1answer
31 views

fluid mechanics

in question A2 part (ii) why P2 is considered to be zero
2
votes
2answers
44 views

Efficiency of TurboJet engines with nozzles

As per Bryton Cycles, most of TurboJet engines' Thermodynamic efficiency should be around 40%. Rest of energy gets rejected as waste heat in exit gases of after the turbine. But if these hot gases ...
-2
votes
0answers
19 views

there is someone that knowing about good screw for high temp? (~500 C) [on hold]

i looking for screw like that and also magnet that good to 150 C thanks
0
votes
0answers
52 views

Machine Frame Design

How do I select the cross section for a machine frame? Do I need to refer to the AISC steel construction manual to find the capacity of beams, columns, etc?
2
votes
1answer
19 views

Spring Industry Naming Convention

I am currently prototyping a part for a personal project. My CAD design was contracted out and there are some off the shelf parts that I need to order per the design (springs, screws, etc.). My ...
-1
votes
0answers
18 views

I dont know how to calculate my electrical power needed to get .5 Watts (heat = 𝑄) [on hold]

Interior surface temp=46C, exterior surface temp = 28C, i'm using polystyrene with a k = .025. it is a cubic oven with an opening on the ceiling; the resistance is located on the floor area (bottom)
5
votes
2answers
59 views

Why do some guyed towers come to a point at the bottom?

Why do some guyed broadcast towers come to a point at the base. It seems that it would be more stable if each vertical bar was anchored separately rather than being balanced at one point.
0
votes
1answer
38 views

Water in basement plug install

I have a basement which floods, the water comes through a drain in the floor. I am therefore looking to use an HFT Pipestoppers to stop the water coming in I think the water comes from an old tank (B)...
0
votes
1answer
22 views

Correct sizing of fastener for console

Following situation: I need to mount a console holding a load to the edge of a 25cm concrete plate. I want you to check my reasoning. This is the situation: My thinking is: The load is 170kg, which ...
-1
votes
0answers
15 views

At what Force does the Rod break? [closed]

There is a rod of diameter D and Length L. During Testing the rod is subjected to tensile load at constant frequency (say 210 Hz).But The force on the rod keeps on increasing during testing. How ...
1
vote
1answer
26 views

What chemical can be used to restore synthetic rubber?

When rubber (I don't know the specifics, but I assume it's butyl rubber) gets old, it turns into one of two states usually: It becomes sticky and gummy. It becomes hard and brittle. I'd like to know ...
2
votes
2answers
42 views

How were horizontal and vertical structures ensured in old times?

In modern times bubble levels and water levels are used to check if a surface if strictly horizontal/vertical. How did people ensure vertical/horizontal surfaces in older times?
2
votes
1answer
30 views

Effect of Pressure on Combustion efficiency (of hydrogen) in excess air

Can somebody explain relation between combustion efficiency and pressure in lean mixtures using any kind of chart or mathematical equations? At first glance I thought, combustion efficiency increases ...
0
votes
0answers
35 views

Can someone please give me a hint on how to draw velocity triangles for this specific inward flow reaction turbine problem?

I'm trying to calculate the hydraulic efficiency for this turbine by using the formula: E(hyd) = (VwU)/gH where Vw= Velocity of whirl at inlet, U=velocity of runner at inlet, H=Given Head, and g=...

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