# Tag Info

### Why would you put covers in front of the output of the condenser fan on these mini-split units?

As other mentioned, it is to provide protection against strong winds directly entering the air outlet. As for the gap, it does seems small but that's what the manufacturers decided to go with. This ...

### Which material index should be maximized for a component in a car's manual type HVAC?

Plastic parts like those are typically loaded far lower than their yield strength to start with, so adding strength by going to steel isn't necessary. Even without a particularly complex mold, a ...
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1 vote
Accepted

### How to solve transient heat conduction equation at a point in space with volumetric heat source?

Picture a container with an area $A$ (m$^2$) and depth $d$ (m) holding a liquid. The container is perfectly insulated and the fluid is static. The fluid has a density $\rho$ (kg/m$^3$) and specific ...
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### Which material index should be maximized for a component in a car's manual type HVAC?

Cost - you are forgetting about processing costs. Yes, engineering polymers might give you least cost/weight. But they can be injection molded - that means cheap, reliable components of nearly any ...
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### Relation between welding bead and outer diameter of a pipe?

There is no relation between welding bead and OD of pipe There is no relation because pipe is not supposed to have a bead inside it. Either you bought defective pipe, or you're in a locale where ...
• 4,668
Accepted

### Relation between welding bead and outer diameter of a pipe?

Looks like ERW pipe with the ID trim die not working. The diameter is very small for DSAW ( double submerged arc welded) pipe and the ID weld bead looks too high. Or, I am wrong and it was welded from ...
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### Torque converter torque multiplication

It’s better to look at the power generated by the torque converter. The power out of the torque converter should equal the power into the torque converter multiplied by the efficiency of the torque ...

### How to control a Stepper Motor with CircuitPython?

As @Transistor commented, having any idea of what is happening or some links to some documentation would be "helpful." That said, a little looking at the adafruit_motor package shows that it ...
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### Mechanical System Transfer Function - Systems Modelling

Your system of equations can be written in matrix form $$\mathbf{M}\ddot{\mathbf{x}}=\mathbf{K}\mathbf{x}+\mathbf{B}\dot{\mathbf{x}}+\mathbf{F}$$ Assuming the direction of positive state variables are ...

### Why would you put covers in front of the output of the condenser fan on these mini-split units?

Why would you put covers in front of the output of the condenser fan on these mini-split units? Weed eaters. Leaf blowers. Spray painters. Pressure washers. Accident prone groundskeepers with pruners,...
• 3,425
1 vote
Accepted

### Industrial (Farming) high precision gps tracking solution

An 8 ton hobby machine? That's quite a hobby! To answer your questions: ublox-zed-f9p is probably fine for production, but it's a terrible choice for prototyping because it's got pad, not wire, ...
• 149

### What is the mechano-acoustic effect of off-centering the black paste on tabla-drum skins?

Simply put, the blobs of paste act to damp out any vibrational modes which would have had mode maxima at that physical location. The energy applied to the drum then goes into other modes, presumably ...
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### In the Rankine Cycle, how does the condenser work without changing the temperature or pressure of the fluid?

Organic Rankine cycle uses hydrocarbon or organic high density fluids. The boiling point and condensation points are lower. the expansion is isentropic and the evaporation and condensation processes ...
• 454

### Why Stirling engine not used as primary source to operate generator in thermal power plants?

Several reasons poor thermodynamic efficiency. It's fairly low. Where as the modern gas turbine has an efficiency of 44-66% and with waste heat capture 80+ percent. stirlings use conduction to ...
• 454
1 vote

### How to calculate the magnetic force for metal on magnets?

If you wish free and open-source software, i can recommend ONELAB, which is combination of Gmsh (mesher and GUI) and GetDP (general purpose solver). You will have an exciting dive into physics and ...
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1 vote

### Understanding physics principals behind machining

Your motivation is great. But you’re confusing the trees for the forest. An important part of engineering is understanding when you need to use complicated models or not. There is little point in ...
Accepted

### Airflow visible over the airplane wing

Specifically, what you are seeing here is a vortex which is basically a sideways tornado. Vortices occur when moving air forms a twisted stream when flowing over an object with a complicated shape. ...
• 12.1k
1 vote

### Airflow visible over the airplane wing

The airflow will be there visible or not. What makes it visible are the atmospheric conditions and moisture or humidity in the air so the water particles show the airflow. In wind tunnels the airflow ...
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### Why is Scotch-Yoke mechanism not used for internal combustion reciprocating piston engines?

Making an engine using scotch-yoke mechanisms for all pistons on a multi-cylinder engine will increase the cost and add a lot of needless complexity and mass, especially rotating mass that won't ...
• 13.9k
1 vote

### Understanding physics principals behind machining

Unfortunately, what @DKNguyen commented is still how the field mostly look like. We lack computer models for most machining tools we use. Unlike EE heavily built on electromagnetic axioms, machining ...

### How to calculate elastic deformation due to kinetic energy (impulse)?

When punching an indent into a piece of metal, the residual stress that is concomitant with the indentation implies yielding and so you have a non-linear interaction. If you still want to do the ...

### How to calculate elastic deformation due to kinetic energy (impulse)?

if we are talking elastic deformation then the problem is easy. you take the kinetic energy of the falling weight at the instant it first touches the object and equate it to the stored strain energy ...
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1 vote

### Why would you put covers in front of the output of the condenser fan on these mini-split units?

They are fragile and easily damaged, so it is common practice to protect them with shrouds. Those shrouds also serve to guide the airflow from the fans that blow air over the coils to maximize heat ...
• 12.1k
1 vote

### What is the safe rpm limit for a solid steel wheel

For a start calculate per: Rotating Disk with hole But it is possible to vary cross-section as bell curve profile to increase speed and reduce weight.
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### Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?

Spreading the upward reaction load from the support pillars is one reason, the function of an arch translating vertical load to horizontal thrust is another. But there are already good answers saying ...
Accepted

### Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?

If I model this as a simply supported beam having load at mid span [...] I suspect that this is where your analysis went awry. First off, you should always model bridges with distributed loads, not a ...
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### Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?

Since this bridge is crossing over a waterway, besides aesthetics, the arch-shaped bridge provides several advantages: Less restrictive over the height of marine traffic due to more headroom in the ...
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### Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?

Simply put, it is because the mass of the spans has to be supported and each pillar has to support 1/2 the mid span plus some of the end section.
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### Can I create a whirlpool/vortex around a horizontal axis in a flat bottle using motor?

What you are asking for, is called cavitation bubbles. Typically, this is a harmful phenomenon in the field of ship propeller screws. It is accompanied by vibration and noise, so likely you will not ...
• 99

### How to split power from a single DC source?

Based on ULN2003A datasheet, its on-state input voltage does not exceed 3V. So, you do not need 5V regulator at all. ULN's inputs go to MCU outputs, ULN's collectors (outputs) go to motor coils ends, ...
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1 vote

### Is there a way of "shortening" a mechanical lever, but keeping its mechanical advantage intact someway?

Although you need to move the ends of the lever through the correct distances to get the correct advantage -- work equals force times distance -- you don't need to have the same linear distance to do ...
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Accepted

### Is there a way of "shortening" a mechanical lever, but keeping its mechanical advantage intact someway?

Input force times distance equals output force times distance. There is no way around this except adding power to the system. If you shorten the throw you must increase the force to get the same ...
• 4,668
1 vote

### Is there a way of "shortening" a mechanical lever, but keeping its mechanical advantage intact someway?

Yes. Assume the load and the force are in equilibrium condition initially. You can shift either the load, the force, or both, toward the fulcrum, so the resulting work done (mechanical advantage) by ...
• 7,491
Accepted

### Could a hybrid system of mechanical levers and hydrostatic/hydraulic cylinders be able to lift 200+ kg with the force of an arm?

Levers and hydraulic cylinders are not typically used for the distribution of force, but are more frequently used to transmit and otherwise modify applied force. Per your reference to class one levers,...
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Accepted

### Torque Problems vs Motor Problem?

The motors have a rated speed of 2750rpm. It doesn't look like there's much of a gear ratio, so at the moment the motors spin at the same speed as the wheels. With 16" wheels, 2750rpm is about ...
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1 vote

### Torque Problems vs Motor Problem?

I would swap the gears between the motor and the shaft, as it looks like you are trying to drive the axle shaft faster than the motor. If you have a small gear on the motor and a larger (*3 or *4) ...
• 13.9k
1 vote
Accepted

### Calculations of a sphere

First, consider a circle with same diameter as the sphere, with the distance $d_2$ being the projection of $D_2$ onto the plane and assuming $d_1=D_1$ relative to your figure: The radius of the circle ...

### How to split power from a single DC source?

If the things need the same voltage then just wire them in parallel. If they don't, then add some regulator or converter so they do. Don't even think about wiring two unrelated circuits in series ...
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### On a car with all-wheel drive, how does the engine provide the angled front wheels with power?

You could also include front-wheel drive in your question. It would be enlightening for you to look at what radio control rock crawlers do. It has much of the excess of a full-sized car stripped away. ...
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### Direction of fluid flow

If this is a pumped system, try measuring the reaction forces when you turn the system on. For example, if you're trying to measure the direction of fluid flow in a hermetically sealed "black box&...
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### Direction of fluid flow

Look at or develop a flow schematic of the system. A cursury examination should give most likely flow direction. Maybe some existing ancillary measurements could give you necessary info.
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### How to design an enclosure around the load cell (Beam type)?

Hi I think a 2 part enclosure would work with this. You need to make sure you have enough tolerance between all of the components so that they do not interfere with the load cell accuracy. I have ...

### Direction of fluid flow

Yes, purchase an ultrasonic flow meter. Needs a straight length of pipe and very careful placing of the sensors. However, if done well one can get good results, if not then the results can be ...
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### Direction of fluid flow

Heat the pipe at some point, and find the direction in which heat transfers. This will give you the direction of the flow. Caution: Don't do this for flammable fluids. Thanks to @Carl Witthoft for ...
1 vote

First step if you find that your children's toy prototype is failing should be attempting to figure out the forces you are putting on it and seeing whether they can be distributed better. Sometimes ...
• 5,666
Accepted

### Ideal design for a long fruit plucking pole

You will want a material with a high stiffness, and strength to weight ratio. If cost is no object, then carbon fiber is probably the best option. Fiberglass, titanium and aluminum are also good ...
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### Determining the angle theta at the Mohr's Circle

There are two different angle $\theta$'s. one is the normal stress angle $\theta_p$between the stress axis, X, and point a(x,s) on the mohr circle. The other is shear stress angle $\theta_s$ from the ...
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### Flow of fluid in branched pipes

If we assume branch 2 is high enough so that the hydrostatic pressure of water column in 2 compensates the dynamic pressure of the horizontal flow, nothing flows out from 2. If 2 is not high enough ...
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