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18
votes
2answers
2k views

What are the major differences between Engineering degrees and Engineering Technology degrees in terms of employability?

What difference in education occurs between two graduates, one with an Engineering Technology degree (be it Civil, Mechanical, Electrical...) and the other with the equivalent Engineering degree "...
18
votes
1answer
383 views

Is there a method to determine the runoff for arid areas in developing countries?

Note: this question was totally rephrased and expanded on, addressing the comments and questions posed to the first version. The de-facto standard source for runoff calculations in South Africa is ...
17
votes
6answers
5k views

Why do oil tankers heat crude oil?

About all those oil tankers off the coast of California … | Grist The giant ships burn fuel to keep lights on, power equipment, and heat the large volumes of crude oil resting in their tanks. I'm ...
17
votes
9answers
27k views

How to stop water flow in a siphon?

I have assembled a small DIY drip-irrigation system for my terrace garden. Please have a look at the attached image. I switch on a small pump to start the drip-irrigation system and then switch it off....
17
votes
7answers
11k views

What are the engineering principles for a train to get electricity from the railway

How many general methods are there for transferring electricity from the railway to a train? I could see that some trains are connected by a pantograph and some have a third rail. Are there any ...
17
votes
10answers
301k views

Pound-force (lbf) vs Pound-mass (lbm)

Given: My thermodynamics text reads as follows: In SI units, the force unit is the newton ($N$), and it is defined as the force required to accelerate a mass of $1\cdot kg$ at a rate of $1\cdot\frac{...
17
votes
5answers
2k views

How are passive houses made in very hot regions (like Saudi Arabia)?

I think, here is the main problem the difference between the internal and the external temperature. For example, in Saudi Arabia, in 50 C, a passive house needed probably much sophisticated planning ...
17
votes
2answers
29k views

How does width and thickness affect the stiffness of steel plate?

I have a 2 mm thick steel plate which is 300 mm long and 30 mm wide, supported at either end. It supports a weight-bearing wheel that can roll along the plate. It currently supports the maximum weight ...
17
votes
3answers
6k views

What is the most efficient means of warming a building with a high ceiling?

Consider a large auditorium, a church, or some other very large, essentially one roomed building with a high ceiling. Suppose that the building has many entrances which enable cold air in/hot air out ...
17
votes
1answer
1k views

Fracture patterns in tempered glass

While browsing a local news site, I stumbled upon this picture of a broken bus door. The glass was fractured due to a rock impact. As far as i know there are no heating elements on the window section ...
17
votes
1answer
63k views

Understanding required torque for a motor lifting a weight

This is a continuation of me trying to understand torque and stepper motors in my other question. I'm trying to understand the torque a motor would be required to generate to lift a small weight, and ...
17
votes
5answers
918 views

Meshing of complex geometrical domains

When using the finite element method, I have always used either already meshed domains or very simple ones. From what I've heard, meshing complex geometries is often outsourced to specialized ...
17
votes
1answer
4k views

How many train passes can railway tracks endure?

I know that the rubber on car and truck tires wear, and the road concrete wears out. I wondered: While steel is hard and elastic, it still causes friction (interaction between molecules) and ...
17
votes
1answer
718 views

Can we change steel properties by application of magnetic field while quenching?

Austenite is non magnetic while $\alpha$-ferrite and pearlite are magnetic. (Magnetic properties of pearlite vary as a function of carbon content) If a strong magnetic field is applied in a ...
17
votes
1answer
2k views

How to design a house to be cooled passively? [duplicate]

I live in Louisiana these days, in an area that is known for its numerous antebellum plantation homes (circa early 1800s). While touring one of these homes it was clear that almost everything about ...
16
votes
6answers
10k views

What limits the speed of a car?

From an engineering perspective, what limits the maximum speed you can reach with a regular car? I understand that some of the faster cars are for safety reasons limited to not run faster than say 250 ...
16
votes
3answers
31k views

Effective ways to drive a single shaft with multiple motors?

To head off the "why not use a bigger motor" question, I'm a high school mentor for an FTC (First Tech Challenge) robotics team, with a bit of a soft mechanical / hardware background. They're ...
16
votes
3answers
37k views

Can wifi signal reception be improved by opening a door?

A wifi user is in a different room than the router. The computer is having a hard time connecting and receiving the wifi signal. Can the wifi signal from the router to the computer be improved by ...
16
votes
3answers
4k views

How does measurement uncertainty combine with tolerances?

Given a tolerance within which your workpiece should be manufactured, say some length should be $10\pm1$mm. If you determine that your uncertainty in measuring this length is $0.2$mm (at 95%). How ...
16
votes
4answers
5k views

Why does the microwave plate start in a random direction?

...or what type of motor is used there? I found this type of motor - usually powered with low-voltage AC (~12V), but at times with 230V, in several appliances that require very slow rotation and ...
16
votes
5answers
3k views

Why don't refrigerators have parts outdoors?

I've always wondered why refrigerators don't have some of their parts located outdoors like an air conditioner. In warm weather, it seems like it would make sense to have the condenser outside like ...
16
votes
2answers
7k views

While going downhill, does my car consume less fuel when in neutral or in gear?

I once meditated on the fact that a car, in downhill, would consume more fuel when in neutral to keep the engine on, rather than in gear. To keep the engine on when in gear, in fact, you mostly need ...
15
votes
14answers
27k views

What kind of math do engineers really use? [closed]

I am from the mathematics StackExchange section, many of my students are engineering students at University. I was wondering what kind of calculus do you real engineers use? I have known two engineers....
15
votes
3answers
6k views

How do bike wheels keep turning when the rider stops pedalling?

I am very confused with something regarding bikes... How is it that a bike wheel continues to spin (either from momentum or from going downhill) when the rider is not pedalling, without also spinning ...
15
votes
5answers
8k views

Does an electric vehicle going downhill recover energy?

I have to model the behavior of an electric car. For this, I use these equations and I can observe by "playing" with parameters that, when going downhill at constant speed, the car has a negative ...
15
votes
2answers
389 views

What is this large steel structure used in excavation?

I keep seeing these large rectangular structures on job sites they put in the ground. I'm guessing something for strengthening the surface structures?
15
votes
4answers
24k views

What material is used to hold molten iron in a furnace?

When iron is melted, I guess it has to be transported and contained. I think the container in which it is has to be able to withstand higher temperatures than what you want to melt. According to this ...
15
votes
3answers
2k views

Why is it more reliable to use the land/pit transition in a CD-ROM?

I was reading about how CD-ROMs work and I came to this: Although it might seem simplest to use a pit to record a 0 and a land to record a 1, it is more reliable to use a pit/land or land/pit ...
15
votes
5answers
5k views

When do I need to consult a professional engineer during a home renovation?

I am a homeowner who likes to save money by performing DIY work. When possible, I prefer to serve as my own general contractor to reduce the cost of a project. However, when I talk with professionals ...
15
votes
2answers
6k views

If aircraft are pressurised, why do our ears pop during liftoff and landing?

Something hit me during my last flight: our ears feel that the pressure around us changes quickly during liftoff and landing, they hurt more and more until we make them pop. However, the cabin must ...
15
votes
2answers
6k views

How do I size metal plates to get the correct dimensions after folding?

I am designing a metal plate that will be laser-cut (or machine-cut) and then folded. I want to know how to size the pre-folded plate in order to get the right dimensions after folding. My actual ...
15
votes
2answers
565 views

What is the physical interpretation of the second term in the viscous stress tensor in the Navier-Stokes equations?

I have been searching for this answer for awhile. I've read numerous texts and even watched some lectures online, but often times this is never explained and just given. The viscous stress term in the ...
15
votes
1answer
1k views

Why are hyperboloid towers not popular anymore?

Hyperboloid towers were very popular in the end of 19th and the first half of 20th centuries - water towers, powerline anchor towers, sometimes tall radio towers were built using this design. The ...
14
votes
8answers
7k views

What are those large poles for that are always in front of US stand-alone store buildings?

Screenshot of a video where they are featured in the background: They appear to have no electronics built in, such as an electric charge station, or a parking ticket dispenser or something like that....
14
votes
5answers
719 views

Are pneumatic tires obsolete?

Adaptive suspensions with adjustment rates on the order of milliseconds are going mainstream in consumer vehicles. Air suspensions have been common on commercial trucks and some SUVs for some time. ...
14
votes
3answers
632 views

Are pontoon bridges being considered to extend bridge span?

Pontoon bridges differ from traditional bridges in that they are supported not by structures anchored to the floor of the body being spanned but by floating pontoons that are connected by a more rigid ...
14
votes
3answers
693 views

Do solar cells age? Why, and how?

As I heard, the life expectancy of photovoltaic cells is normally some decades, as so. This is very long, regarding their high cost, it has significant (negative) effect on the total costs. Why do ...
14
votes
4answers
3k views

If the emergency brake in a train is broken, do the passenger car brakes still work?

Scenario: Suppose the emergency brake button in the cab of a train is not working. Would the emergency brake cords / buttons in the passenger cars still work? This question is inspired by this ...
14
votes
7answers
21k views

Is stainless steel plating possible?

Is there a method for plating steel with stainless steel? If so, is it chemical, electrical, or electrochemical? I did a quick search on the internet but was unable to find a service. I'm ...
14
votes
2answers
3k views

What is this small rotating part from a cell phone?

What is this tiny rotating piece of hardware that I found inside my Samsung GE1202? It has E9C written in blue on it.
14
votes
2answers
3k views

How should I position two shelf supports for the best distribution of load?

I'd like to mount a shelf on the wall. I have two shelf supports to do so, like this: Relative to the shelf, where do I place the (blue) supports to achieve the best distribution of load?
14
votes
3answers
4k views

What happens when you put the wrong type of fuel in an internal combustion engine?

What happens to the working of petrol engine when it is emptied and filled with diesel or to a diesel engine emptied and filled with petrol? Will the engine be able to operate and, if not, why not?
14
votes
4answers
1k views

How should the public raise questions about unsafe structures in the United States?

In a program on NPR that I was listening to, there was a bit about a bridge that from the description sounded to a layman as unsound and is still in use. The program described it as an old wooden ...
14
votes
3answers
5k views

Can I use a ultrasound sensor to measure water level?

If I use an ultrasonic sensor will it detect the water level? I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this ...
14
votes
2answers
579 views

Why are lasers used for concentrated light applications instead of incoherent light sources?

Some laser applications consist simply of concentrating light into a small spot. Two example applications are laser welding and cutting. In these cases a CO2 laser is often used which needs a ...
14
votes
7answers
9k views

Why is air pressure in all directions?

Here is a typical definition of air pressure: Air pressure is caused by the weight of the air molecules above. Even tiny air molecules have some weight, and the huge numbers of air molecules that ...
14
votes
5answers
6k views

Purpose of spheres and fins on submarine propeller

On a recently launched Russian diesel-electric submarine, the rear propeller has two distinct features. You can see spheres at the base of every propeller blade: Also, the trailing edge of the shaft ...
14
votes
4answers
3k views

Derivation for bridge natural frequency estimate in Eurocodes

The Eurocodes gives the following equation for estimating a "simply supported bridge subject to bending only"*: $$n_0 = \frac{17.75}{\sqrt{\delta_0}}$$ Where $n_0$ is the natural frequency in hertz ...
14
votes
4answers
2k views

In aluminum machining, what are the most common factors that might cause a machined component to have warping issues?

I am currently having an issue where features of my machined parts are warping. I am using Alloy 7050 Type I and Type III in this particular case. Using a feeler gauge and a certified, calibrated ...
14
votes
2answers
329 views

Modern method for teaching controls

Background When I took my first class in controls (2006-ish as taught by an aerospace professor for a mix of ME and EE students) it was basically all done in Laplace-transform, transfer functions etc. ...

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