Questions tagged [unit]
The unit tag has no usage guidance.
34
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Fundamental error when assuming "per unit Celsius" = "per unit kelvin"
While doing a chemical engineering question today, I came across something quite fundamental that I can't seem to get my head around.
I had a value in bar/°C, and I had to multiply it by a temperature ...
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1
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44
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Confusion regarding SI units of K (stiffnes)
I know that stiffness, K is equal to product of moment of inertia and square of natural frequency
K = Jωn2
Where K = stifness, J = moment of inertia and ωn = natural frequency
SI unit of J is kg m2, ...
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3
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1
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What mathematical operation should I do in order to translate from TWyr/y to TWyr_30 in this article?
In this article
https://www.sciencedirect.com/science/article/pii/S266711312200002X
the authors show a result of prediction on energy reserves (in particular solar ones) as known in 2015 (Figure 1) ...
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2
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Strange units with UV water disinfection systems
When retrieving information about UV systems for water disinfection I frequently encounter minimum intensity values.
e.g. here: Basics of UV disinfection, page 23
All those I find are given in a unit ...
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3
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Unit of blower speed
I want to know whether the international unit of blower speed is RPM or r/min. I konw ther're the same, but I'm not sure which one is more prevailing internationally. Thanks for answering.
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2
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units check for horsepower to weight (Hp/W)
is this units breakdown correct:
Hp/W= (ftlb/s) / (lbft/s^-2) = s^-1?
I think I might made mistake?
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-1
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2
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General Units question
so let’s say I worked out a quantity that turned out to be unit less but to work it out I used pounds (lb) and feet (ft) and the units cancelled out
But then I used this unit less number later in ...
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2
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Convert from RPM to per second [closed]
Is this correct please for my conversion from RPM to per second? I've included my working below:
(500 / 60) * 2 * π = 500 rpm to just s-1.
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1
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37
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Reading odd dimensions
I am reading a paper and the dimensions for some electrodes are given, but I was wondering if I was reading it properly:
30 × 15 mm2, is this the same as: (30 × 15)mm2 ?
To track the published paper I ...
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1
answer
677
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What does MM prefix mean in MMtoe?
I was reading documents about energy importation and came across the following:
The import was of 5,915.87 MMtoe
I wonder if MMtoe = $10^6*10^6$ toe = $10^{12}$ toe.
First time coming across a ...
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3
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2
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Unit of "cN.m" used on torque wrench
I'm using a torque wrench whose unit is cN.m. I wonder what unit this is, and how to convert N.m (Newton meter) to ...
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What unit of weight is that?
Recently I was weighting stuff with my dad and as I was playing with one of the old 2 kg weights I felt with my fingers number "5". After cleaning and upon further inspection it turned out ...
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1
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73
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Thermal conductivity listed in the rather complicated Btu/s-in.²-°F/in - am I converting this right?
I'm currently working through some rather old documentation which gives the thermal conductivity of a material as 9.8 x 10⁻⁶ Btu/s-in.²-°F/in. There are many typical ways to give a thermal ...
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2
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84
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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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1
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41
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Half-life Unit Notations
I was looking for some element's half-life, on the following website:
http://nucleardata.nuclear.lu.se/toi/listnuc.asp?sql=&A1=214&A2=214&Z=88
For 214,88-Ra, the half-life is shown to be: ...
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367
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How can I calculate the density of air?
I major in chemical engineering, and I'm solving a example of unit operations.
The textbook is Warren L. McCabe, Unit Operations of Chemical Engineering 7th ed.
Here is example 24.1.
And this is its ...
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1
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Weibull distribution Units - ENGIEQSOL
I am using Engineering Equation Solver, and it has been telling me the units of my distribution are inconsistent.
According to a the book I am reading, I think it should be unitless (as it is a ...
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7
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Forgotten time units
As my kids are counting down to Christmas, I came to wonder how did people measure time through history. More precisely I wonder about unit systems for precision time keeping of years past gone.
I am ...
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2
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6
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657
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What is the accepted way to write units when specifying multiple dimensions?
When writing out dimensions in the form height x width x depth, what should you write for the units? For example, I can think of a few ways to approach this (assuming each dimension is measured in ...
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1
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How to set measure display units in Solidworks drawing?
I have already set millimeters in document propertis, nevertheless the display units are meters
Why and how to fix?
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2
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Converting flow rate from normal/standard liters per minute to cubic meters per second
I'm really confused about these three units commonly used for measuring airflow:
cubic meters per second (m3/s)
normal liters per minute (NLPM)
standard liters per minute (SLPM)
I would appreciate ...
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2
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733
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Questions about newton metre units
I have a few values in Newton metres and I need to make sure each value is an SI unit for calculations. However when I try to search for the units I am given, I can only find similar, but not quite ...
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6
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Engineering calculations in a tool that will handle units [closed]
I know Mathcad handles units along with numbers which makes it easier to avoid errors by tracking units the way we would by hand.
e.g. 250 kW + 500 W
I just ...
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1
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147
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Unit Conversion for Mass Density
I am doing a Finite Element analysis of a continuum. In my problem definition I use these units:
mm for length, kPa for applied stress, and MPa for material stifness (Young's modulus).
With these ...
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1
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110
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US customary units below 1 mil/thou?
I have been asked to provide some of our technical docs in both metric and US units. For the most part, that is easy enough:
approx 1cm → approx 1/2"
500μm → 0.02"
But then I start getting stuck:
...
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4
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416
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What's the current nomenclature for "English" system of units?
Is the term "English units" still in current everyday use? I do hear this term among other engineers I work with but I'm unsure if this is a localized usage or is consistent with the wider ...
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1
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2k
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How do you convert "kps" to Pounds per Square Foot (psf)? [closed]
I'm looking at a soil bearing capacity report, which has a column labeled "kips" and the values are followed by "kps".
A "kip" is 1000 pounds, but I'm not sure how to convert from "kps" to psf.
The ...
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0
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Did the pressure unit "bar" change definitions since the 1930s?
I don't see anything in Wikipedia about it, but (from this question) when I try to reproduce the equations in this 1933 paper, I get values 106 away from the values in the paper. When I reproduce ...
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196
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How do I denote someone weight
How do I say my weight? In which SI units? I see people are using Kg as a unit of denoting weight from my childhood. Answer this question "What's your weight?".
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2
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Darcy to SI permeation units
How can permeation units in Darcy be converted to the SI form. For example, how would 9.0 x 10-6 darcy be converted to SI units of permeation? How would it also be converted to the permeation units: (...
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I need clarification on how pressure is measured
I have a vessel that has a pressure measuring device. The value it shows as the pressure inside the vessel is 6 inches of water column. Is inches of water column meant to always be used as gauge ...
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Units to use in this formula?
Should standard SI units be used in this formula or are other units supposed to be used for the formula for stress in a thin-walled spherical pressure vessel?
$$\sigma_{yield}=\frac{P_g r_i}{2t}$$
...
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302
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Definitions of strength?
Can tensile strength be the same as yield strength? Can Flexural Yield Strength be related to the yield strength of a material in any way?
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What is pros of weight density?
I've been studying mechanical simulation with nastran/patran, nowadays.
I knew weight density is used in imperial unit system, instead of mass density.
I feel using weight density is tedious, ...
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