Questions tagged [mechanical-engineering]

Questions within the problem domain of mechanical engineering. Mechanical Engineering can be a broad field; consider choosing more specific tags if they apply.

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53 views

Why ΔH has two separate equation in my textbook?

ΔQ = ΔU + Δ(PV) (First law of thermodynamics) which has the same statement as the 1st equation. $Q_p$ or ΔH= ΔU + PΔV which is the heat exchanged at constant pressure. Then why in the image above in ...
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2answers
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Difference between Hydraulic cylinder and spring

What is the technical difference between a hydraulic cylinder and a spring? For sure, I understand their principles but I wonder about physical-technical differences. For example, the most obvious ...
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Difference between temperature and heat

It is becoming very difficult for me to understand the difference between temperature and heat. About heat all I have read : Heat exchange is related to as exchange of matter + energy. Heat is ...
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0answers
60 views

Interpretation of Integral of Differential 3-Form over 3-Manifold in Engineering?

[This is a repost of https://math.stackexchange.com/questions/4164258/interpretation-of-integral-of-differential-3-form-over-3-manifold-in-engineering.] So, the standard interpretation of a ...
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Plane Wave Expansion method

I have very recently ventured into the domain of periodic structures. In the literature, I came across the Plane Wave Expansion method to compute the dispersion curves. I managed to code it in 1D . ...
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1answer
46 views

What is heat , chemical energy and thermodynamics laws restrictions

Below is a text over which I have my questions which I have written below this text: Chemical energy stored by molecules can be released as heat during chemical reactions when a fuel like methane, ...
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5answers
5k views

Why does temperature not increase by putting more logs into the fire

Why does temperature not increase by putting more logs into the fire ? It is a very common observation which I have seen but after some research online I found that it is not completely true. One ...
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2answers
50 views

Difficulty in understanding the scenario for this Q

Q:If a closed rigid wall container filled with 20 gm of He moving at a constant speed of 10 m/sec is stopped abruptly to stand still, find the increment in temperature of this He sample. My question ...
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1answer
35 views

Determining the Angle based in Tension

I am trying to solve the following problem, but got lost in the process. I am trying to find the minimum/maximum angle ( θ ) needed to have the system in equilibrium without breaking the ropes which ...
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27 views

Stokes Number (characteristic length)

I am working with a high speed flow that is non-stokesian, but that isn't the issue. There are correction factors for that. I am attempting to figure out what value to use for the "characteristic ...
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1answer
41 views

Do throttling devices need valves?

Why is it that a throttling device always has a valve leading to it? If in a closed system loop, a cooled gas exists right before the throttling device, shouldn't the sudden decrease in cross-...
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Why would a magnetic sight glass indicate a wrong water level in a surge tank?

In a pumping station that i work, there is a magnetic sight glass attached to a surge tank which I guess there is something wrong about it because when I isolate the tube, drain it and reopen the air ...
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1answer
70 views

What is the possible reason for a huge discrepancy between measured vibration by vibration meter kit and a vibration transmitter?

I work in a pump station and I've noticed that when I measure the bearing vibration by a vibration meter, the measured value differs from what is shown on the computer monitor (2.5 mm/s measured ...
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1answer
70 views

Free body diagram of a differential-drive mobile robot

I'm trying to study the free body diagram of this differential-drive mobile robot in case of straight trajectory (same torque applied on both of rear wheels) and pure rolling motion I started ...
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0answers
41 views

I've bought a DIE without a tap [closed]

So I bought a lovely cheap second hand die to create wooden threads on ebay it cuts: If i measure in metric it taps a 38mm diameter at a 6mm pitch OR if I measure it in Imperial it appears to tap 1 ...
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1answer
57 views

How should I lubricate my gears?

I am doing an experiment testing different types of gears, the gears are fairly small, with gear 1 being approx. 35mm in diameter and gear 2 being 45mm in diameter, and both are meshed together, there ...
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1answer
47 views

How to compensate for losses in a hydraulic system?

I have an engine ( 72240 kW... ) , probably the biggest internal combustion engine in the world and this engine has no camshaft. Instead it has an hydraulic system which controls the combustion, the ...
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1answer
66 views

How to design an enclosure around the load cell (Beam type)?

Hardware and Electronics Used: Arduino UNO, HX711 ADC Load cell amplifier, Load Cell (2Kg); Currently, I am working on a project which requires me to put load cell along with the other circuitry in an ...
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1answer
122 views

On steam locomotives with six driving wheels, why are the rear set of wheels placed further apart from the other two?

So, as the question states, on steam locomotives with six driving wheels, the rear wheels are farther from the middle wheels than the front wheels are. You can see it in these pictures: It's ...
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0answers
91 views

Will high velocity air directed underneath a half-toroid shaped Coanda saucer by a centrifugal impeller create a lifting force?

I would like to know if a lifting force will be created by the Coanda effect from high velocity air that is directed underneath a half-toroid shaped saucer by a centrifugal impeller. I am seeking an ...
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1answer
47 views

Calculating the diameter of screws that are on radius 160mm from axis of rotation. I need help - I don't know If I'm thinking in the right way

First of all, english is not my first language so if there are some mistakes I made - I'm sorry and I hope everything is understandable. The example I am trying to solve reads the following: The gear ...
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1answer
49 views

Component selection type for fluid-mechanical system

I am creating an enclosure and need to get a water supply through a plastic wall inside to the core device. I imagine this water line will be a flexible tube and will screw on or snap to an adapter on ...
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0answers
49 views

Thread adapters larger than 1/2"

I have a 1/2-20 stud that I need to step up to a 3/4-16 stud. I searched around for 1/2-20 female to 3/4-16 male thread adapters, but was only able to find such a product on McMaster for sizes 1/2 and ...
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3answers
192 views

Why do we write T cos theta = mg for this Q instead of mg cos theta = T

For this Q , the author of the textbook writes that T cos 45 =mg but it also states that mg cos 45 is not equal to T. I got to know about this because this is the way , I solved it first. My Q :1 is ...
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2answers
57 views

Effect of centripetal acceleration on angular acceleration

$a_t$ = $\frac{dv}{dt}$ = $\frac{d(r*\omega)}{dt}$ = $r $* $\alpha$. $a_c$ = r*$\omega^2$ = $\frac{v^2}{r}$ These are almost all the variables and values associated with centripetal and tangential ...
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3answers
55 views

How to guess direction of friction in any case

Here , in case of a death well situation as an example. Q How is direction of friction going to be opposite to mg or in upwards direction ? Why not: In case of like circular turning , direction of ...
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3answers
40 views

Is there any frame of reference in which we can neglect the gravitational force?

There is a laboratory in which there is a string tied to a bob on the earth.Consider the earth is perfect sphere ,rotates on its own axis in a circular path with uniform angular velocity. Main Q of ...
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36 views

What is the simplest way to convert this oscillating angular motion to (incremental)rotation? and some Q on viability of lin. wind energy extraction

Intro; I'm currently obsessing over linear energy extraction from wind; a surface to extract the maximum amount of energy from wind in one stroke, then rotating/changing shape on the aerodynamic ...
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3answers
354 views

Meaning of quarter hole color fill in drawing

In this drawing 4 of the holes have the top left quarter filled in black. What is the meaning of that? It it some special type of hole? The drawing is from a Waveguide and in the specs it says ...
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1answer
56 views

How to calculate maximum rpm for a wheel? [closed]

I have a DC motor with a rated rpm of 2750. At max rpm, the rubber wheel that I've attached to it is pulling itself apart (literally, the rubber is being pulled away from the central hub due to the ...
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1answer
52 views

Degree of freedom of a mechanism

A mechanism popped up in my mind when I was studying kinematics, see picture below $J1,\ J2,\ J3$ are rotational joints and there are two translational joints $J4$ and $J5$ between two sliders and the ...
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43 views

Manual vs Fusion360 calculation of natural frequency of beam

I'm trying to uncover the natural frequency of a mass-less beam with 2 masses attached but getting different answers from Fusion360 vs a hand calculation. L1=1m, L2=2m, m1=10kg, m2=20kg, Young's=...
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2answers
67 views

Response time and time constant of Mercury thermometer

I searched to find differences between response time and time constant of a thermometer. So I found that those two are not same and we have to get 99.3% of the total step change to find response time ...
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1answer
63 views

Do really "all mechanical watches need to be maintained properly"?

Somebody answered this on a different question: All mechanical watches need to be maintained properly. Every year or two they should be taken to a watchmaker for a service. This will include ...
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19 views

Constructing a structure with given constraints

I have a problem where I have a few points in 3D space with given constraints (forces, moments) and I have to create one connected structure which satisfies these constraints. Are there any pre-...
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3answers
93 views

Are mechanical pocket watches inherently water-proof and last "forever"?

Recently, I bought a cheap (~$53) but elegant mechanical "retro pocket watch", newly made. That is, not an antique made in the 18th century or anything. So far, it's worked flawlessly and ...
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3answers
88 views

Would a car slip down on a frictionless banked road and situation for friction road

Here , we have a car on a banking road. Considering two cases : Frictionless and friction surface of the road. I give an initial velocity to the car by a push for a second. Then , the cases discuss ...
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0answers
18 views

Control Partitioning in presence of external disturbance force

I am simulating the dynamics of a control system that has been designed using the control partitioning technique (model-based control + servo control). I am having a query for the case when an ...
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0answers
50 views

How is a plank able to stop a spring door [closed]

So , here we have door which can get closed on its own due to spring. Agenda of Q is to put sth beside the door so that the door does not close . The Q tells us that when we put a brick of 0.5kg. Door ...
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1answer
34 views

calculate torsion in a diffrent sized shaft

first of i know it seems like a homework assignment but it does not, it is calculations i need to do at work and it has been a long time since i studied this material. so I need help to calculate if a ...
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0answers
50 views

Why does a system with zero resultant moment turn after temporarily force-tilted?

Say a beam, 3m long from end to end, has a pivot placed at its centre of mass, at half its length i.e. 1.5m. Objects with weight 200N each are placed on both ends of the beam. The system is in ...
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2answers
87 views

Effects of rolling resistance on wheel angular and vehicle longitudinal speed

The differential equation for wheel speed can be given as: In here, $T_t$ is driving torque (not braking), $F_x$ is longitudinal force of tyre, $J_w$ is wheel inertia, $\dot{w}$ is angular speed of ...
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0answers
27 views

How to determine minimum aluminum t-slot profile type for frame?

For a frame with dimensions 1000x1000x400, I am determining which T-slot extrusion type will be strong enough. I am considering both 30-6060 (30 series I-type, metric) and 20-4040 (20 series I-type, ...
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2answers
31 views

Weight distribution on sliding or “pocket” doors

Does anyone know if hollow sliding/pocket doors have a weight/more dense wood at the bottom of the door to prevent from swinging?
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1answer
66 views

How to calculate reaction moments and forces in a fixed axle with multiple point loads?

I need to calculate the maximum moment and reaction forces in an axle with both sides fixed in bearings, the axle is 1010mm long and has downwards forces of: 236kN at 403mm 86kN at 499mm 32kN at ...
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2answers
71 views

Find minimum horizontal force required to keep the block and wedge stationary?

In the adjoining figure, the coefficient of friction between wedge (of mass M) and block (of mass m) is μ. Find the minimum horizontal force F required to keep the block stationary with respect to ...
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22 views

Model for dynamic plate deformation

I would like to gather ideas to model the dynamic behaviour of a plate with variable thickness. The assumption are: Small deformations. The plate is all made of the same material with variable ...
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1answer
81 views

Why does my trimmer feels heavier when it is operating and its fully charged?

I have a Philips trimmer which when fully charged feels much heavier than when it is not charged. Also , the blades move much faster when it is fully charged I.e it’s weight , speed of blades kind of ...
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0answers
52 views

Is it possible to narrow down a portion of shaft to its 1/5 of its diameter?

I designed this shaft for my center gripper. However the slot requires to be very deep, as you can see. I want to know if it's possible to produce this part. The main diameter is 30 mm and the small ...
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2answers
65 views

How do I read this schematic drawing notation for a drill hole?

It's for an NX part. I can't figure out the depths and such. I just know the placement of the 4 holes and that the diameters are 10 mm each.

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