# All Questions

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### How do I interpret the following Bode, Nyquist and Nichols diagrams?

I am working with an arbitrarily complicated and long-winded transfer function that looks something like this: $$H(s) = \frac{as^4+\cdots+b}{cs^6+\cdots+ds^2}$$ where letters represent constants. ...
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### BMD of the beam joined at intersection

4 beams are supported by the column at one side, another side is jointed together at the intersection. I have assigned UDL of 20 kN/m on all the beams. 2 beams are longer (3m), 2 beams are shorter (2m)...
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### Inconsistencies with units for thermodynamic identities

I am working out the temperature for an Ideal diesel cycle: Based on the isentropic properties for an ideal gas. $$T_f = T_i * r^{k-1}$$ Where $T_i = 50 ºF = 510ºR$ If I use ºF, then \$T_f = 172.9ºF = ...
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### Building lightweight 1 km high fence

I would like to build a fence that is 5 km2 and height of 1 km. This wouldn't be feasible as the material needed and cost implications plus environmental factors. Therefore I thought of finding the ...
20 views

### What is the cheapest way to build a fireproof box?

I'm breaking my brain for a two weeks trying to find a way to build a fireproof box 100 cm × 100 cm × 100 cm with 1 door at the cheapest price. The immediate candidate is sheet metal, which needs to ...
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### Mechanically increase motor torque

An electrical engineer here. Using a stepper motor for a robotic arm. A stepper motor at the base of the arm has a max holding torque of 6kgcm. The arm is around 30cm in length from this base motor ...
39 views

### Energy required to liquify gaseous oxygen?

Does anyone know where I can find some documentation of a real-world liquification process, and the energy costs? I can calculate the heat that must be removed from O2 gas to get to liquid, but how ...
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### Convert rock permeability from m/s to m^2

I am studying rock caverns lined with concrete for compressed air storage. I would like to know if it's possible to convert the permeability coefficient from m/s to m^2 or Darcy. Thank you.
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### Proof of angular velocity identity

I've been going thru the book by Hodges and Roithmayr regarding dynamics theory and I can't seem to prove that: I have tried using multiple substitutions, including the fact that every component of ...
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### cavity scaling around part features

I'm trying to add a cavity in part A using part B in an assembly. I'd like to expand the cavity uniformly away from the B around each feature. Instead, the cavity seems to be expanding from the center....
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### Are there any frictionless objects or is it possible to create frictionless objects?

In the latest StarTalk NDT says that without friction space crafts would not be able to slow down when reentering orbit. The friction against the air slows it down from 17,000 miles per hour down. ...
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### Why do heat pumps take more time to heat up a space than resistive heaters?

I was wondering why do heat pumps heat a place so slowly as compared to the resistive heaters? (This thought just came to my mind when upon ironing my shirt the iron became hot quickly which is a ...
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### measurement accuracy in %

I am running a simulation of fluid flow and then doing an actual physical experiment to confirm the results of the simulation. My simulated results show a value of 0.529 m/s and my experiment show a ...
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### Specific heat at constant volume used in non constant volume processes

I have commonly seen that the work for an isentropic compression is written as: $$W_{in} = c_{v}(T_1 - T_2)$$ What confuses me is that since it is a compression (volume is changing) why do we use ...
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### Calculate the temperature stability of wavelength demultiplexer

Hi ive been given this question: A wavelength demultiplexer (DMUX) used in a DWDM communication system has a channel spacing of 100 GHz. The operating pass band of each channel is 50 GHz. The ...
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### Finding force distribution using accelerometer data

The team I'm currently working for is trying to compare bushings with different durometer ratings in the front suspension using single axis(z) accelerometer data during curb impacts. The current ...
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### Mechanical Engineering: Pulley Physics and Equivalent In Axial Rotational Gear Machinery

I have looked at pulley physics at this link and this link and this link. Conceptually, is there an equivalent method in physics to do something similarly in axial gear machinery so that the force ...
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### Active noise canceling for CNC enclosure

this is my first post here! I wanted to share my ideas for this and get some input on them. My parents were kind enough to let me put a cnc machine in the loft. (shapeoko 3 xxl) In order to make them ...
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### Is there any cost effective static stress simulation for rapid prototyping (FDM / 3D-printing)?

I've been using the static stress simulation (computed locally) which, until recently, has been free with the Personal licence of Fusion 360. Is there a reasonable alternative? The cost that Autodesk ...
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### What can I coat on Stainless sheet (316 L) plate to achieve high thermal reflectivity?

I was thinking of using some Aluminum coating/blanket but the temperatures can reach 550C+ in the Chamber I work at. I am concerned about melting. Let me know. P.S: I am an entry level Engineer. ...
165 views

### Identifying zero force members

My instructor said that if a joint has reaction support attached to it, then it is not a zero force member. However I saw in this figure that joints E and A are attached to a pin and a roller, ...
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### Are concrete screws suitable for repeated removal and reinstallation?

Is a concrete screw like the HILTI HUS3 removable? I.e. can it be repeatedly unscrewed and reinstalled as required? Will this damage the fixing or the hole in the concrete? We're thinking about using ...
63 views

### Questions about a controlled demolition video

I came across the following Youtube video which shows the controlled demolition of a chimney. https://www.youtube.com/watch?v=Sb62_QesDTw The construction of the chimney appears to be reinforced ...
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### Calculating the change in flow rate with a change in pipe diameter

At datum height I have a pipe A (ID = 25mm) that discharges water at a volumetric flow rate of 10l/min, and unknown pressure. When this pipe is connected to a polyethylene pipe B (ID = 12mm), 50m ...
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### Can waste heat in specific environments be collected into photons and converted to electricity?

This question is a repeat of another post on the physics board Here and here show the possibility to combine photons of lower energy to higher energy. Thinking of an application, it could be used to ...
39 views

### Why does a hot knife go through butter more easily than a cold knife? [closed]

How does a hot knife go through butter more easily than a cold knife; Be sure to add: A claim to answer the question Difference in objects' thermal energy Explain how thermal energy is transferred ...
28 views

### Identify abrasive pad

I am trying to find a part number for this pad ( see attached). 4" wide, 6" long, 1.3" thick. Very coarse. I know this is a weird question and will probably be closed. Anyways, we have ...
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### Where do I start with learning how to transfer data via RF

So I literally have no idea where to start but I know what I want to make. The goal is to somehow transmit 25mb/s of data across 15km with high penetration. Acceptable for reaching through trees and ...
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### Ripple tank simulation for simulating light waves?

Can anyone help shedding some light on how ripple tanks are programmed? example I'm looking to simulate light waves, to perform theoretical calculations, as opposed to for just visual effect. The ones ...
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### How to add a gap when splitting for joint in Solidworks

I drew a puzzle like joint sketch and split a body with it for 3d printing. But I have to add a small gap between them for the tolerance of the machine. Any way on how to do it not manually?
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### Manufacturing with glass panels [closed]

I would like to design a 3.2-inch LCD display onto a product. The best aesthetic I have seen is using a flush glass screen front face. My product does not use touch screen. How would I go about ...
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### How to calculate minimum and maximum cross-section of a compression clip

I am trying to design and 3D a custom snap in fastener, and I am having a hard time figuring out what cross section it needs to have so that it does not break when compressed, but also isn't so that ...
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### Power distribution problem in multi-camera usb array

Problem Summary My MacBook Pro (development system) can successfully capture images from 24 cameras in the multi camera assembly we have assembled. But when our assembly is attached to a new Raspberry ...
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### Choosing a Project

Sorry if there’s any spelling mistake... I don't know if this is the proper place to ask, but I guess if it isn't, I'll get notified. Anyway, if it isn't, I apologize. I’m a telecommunications ...
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### What do you call the modern architecture of Japanese cities like Tokyo? [closed]

As in, is it modernist, postmodernist, structuralist, brutalist, internationalist? I tried searching it, but couldn't find a clear answer.
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### Vibration following an impact

This high-speed video shows a cymbal's response to impact. I'm interested in how the observed vibration relates to the modes and frequencies that an eigenvalue vibration analysis would predict. My ...
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### Filler Material

If I was to add a filler to a metallic substance, is it possible for the Young's modulus to decrease as filler content increases? Also, when a filler is added, how do the atoms change for improving ...
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### How do I calculate final equilibrium temperature of a pot of water on a stovetop vs. after I add food to it?

So I'm trying to come up with a simple hack to heat up food in a water bath to hopefully +-1ºC of a target temperature, but I really don't understand the physics of it all so much. I'm pretty sure I ...
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### Calculating Z-axis Torque on a 3-D Printer

I recently built a large CoreXY 3D printer and I am wondering if my 4 z-axis stepper motors combined will have enough torque to accelerate the build plate with a heavy 3d print. During the building to ...
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### How do I connect a 3mm water tube to a plastic box?

I need to connect a 3mm inside-diameter tube from a solenoid valve to a plastic box. The box wall thickness is 4.5mm. The purpose is to empty water in the box when needed. How should I connect it so ...
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### Minimum drum wall thickness when rope wrapped around it

I need to design a hollow drum that holds steel wire rope under tension. The wire rope gets pulled from both ends with a force of 200kN, it is wrapped around the drum 5 times. The outer diameter needs ...
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### Pressure loss of a shape change of an ar duct, keeping the area the same

I have an air duct 400x400 mm that will attach to an engine with a ventilation opening 981 x 167 mm. I assume a smooth funnel of about 500m length between the two shapes (that's about as much space as ...
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### How to calculate beam impact problem

Can anyone help with this Impact problem? It does not seem very difficult but I am having trouble putting all the parts together. Thanks,
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### Can I get some help solving this statics reactions problem?

I'm working on this reactions problem. I know M(ay) is equal to 0, but I haven't been able to figure out how to solve for the tension in cable BC, forces A(x) and A(y), or moments A(x) and A(z). I've ...
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### How can I achieve good diffusion from an LED light source?

I have a light fixture which is designed as three rows of LED light strips. The problem is that the LEDs appear as brilliant points of light. In the fixture I want to diffuse this light so that it ...
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### Examples of situations where using classical control methods are better than modern methods

I'm doing some reading on control systems at the moment and when reading pages on classical control methods, some sites state that they are preferred in industrial applications. I've read that simple ...
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### force required to bend .375 thick aluminum tab

We are trying to determine the force that was needed to bend an aluminum tab on a piece of our aircraft equipment. The tab is deflected 2 inches and is 3 inches in length. load was at the tip (3 in ...
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### Constructing a Free Body Diagram (Stacked Blocks)

How can I construct the free body diagram of this figure? I am in a topic of equilibrium of particles so the total force will be equal to zero. The two springs are indicated to give equal forces. Am I ...