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But why are you assuming the process is reversible?

Looks right to me, standard flow energy equation.

I have to agree. The brushless design is too expensive and the power supply is too bulky. I would start at the cheapest, 56C frame ( about 1/4 to 1/3 HP) single phase AC 1800 motor and marry the appropriate gearhead. I don't think you need VFD here.

"To be honest it's hard to get a motor which can do 250RPM at 12Nm, so I'd guess it's even harder getting something with 20Nm+ at 250RPM." You don't need exactly 250 RPM and nor should you be thinking of a fixed RPM; you are talking a transient problem reuiring 12N-M with a time frame of speed...

Your cost will depend on how fast you need to perform the task, how often, the type of load you are driving and the motor life desired. So, why don't you tell us EXACTLY what you are doing and then you can get meaningful answers. Otherwise you will only be getting the best guess from the...

Heat pump equations In a cycle Qr-Qin=W Qr=heat removed from refrigerant and added to room Qin= heat absorbed by refrigerant removed from atmosphere W= work done on refrigerant Qr/W= COP So it is correct to say that the atmosphere is being "cooled" albeit infinitesimally. Qr is heating of the room

".. The site accerlations are usually provided by our client and if not, we hire a geotechnical group to produce these values. So getting the actual site parameters is not typically an issue. Once these values are known along with the amplification values, the site specific, damping specific...

Sounds like a simple kinematics problem. Maybe you should post a drawing of the hinge location and show a few positions of the panel. I think we may be able to help you through it.

So this big mystery amounts to getting the published spectra depending on where the structure is located, period.And what happens when you don't have that seismic data? If you don't, then I doubt that you can make a meaningful extrrapolation in going from .02 to .05 damping.

"In regards to Section 11.4.5 of ASCE 7-05, would someone please advise of how one would adjust the Design Response Spectrum curve for a damping ratio other than 5%? I’ve had multiple contradicting statements such as, “the system R-value accounts for the damping associated with that structural...

"Do not need I. Assume mass is concentrated at the center of gravity." With assumptions like that, I would take Rb's center of box as better.

"Pendulum still sounds simpler. Suspend the box. Measure time for one swing cycle. Calculate distance from point of swing to cg. The rest is measuring distance from point of swing to bottom of box support structure and subtract calculated pendulum length". Not a simple pendulum. You need I.

You don't use a central heating system to heat up pool water. Google "pool heating systems" and you should get plenty of info.

"With enough qualifiers, it might be true for an ideal gas. You would have to have a situation with: Constant volume Zero leakage of gas from the volume Zero added gas to the volume Zero chemical reactions within the volume (e.g., you would have to keep sunlight out since high...

"What planet are you doing Engineering on? I cannot think of a single equation that applies to a fluid that that statement would be true. In fact the equation you are calling "the first equation" is OK for ideal gas (the only ones I know of are Air and Nitrogen). It is nearly never true for...

" The first equation is universal and is valid for any ideal gas under any conditions" If you bothered to look, I said "IDEAL GAS"

You meant (1) (P2/T2) = (P1/T1) P2/P1=T1/T2 constant volume (2) (P2/P1) = (T2/T1)^(k/(k-1)) must have volume change The first equation is universal and is valid for any ideal gas under any conditions The second is a reversible process in which work is done on or by the medium which...

"-the alternative; take two guys with four wheel scales, blocks of wood, digial camera, and tape measure; 1 day lead time and cost is about $500; its effective and its gets it done cost effectively" And how sure are you that the equation that you need to perform this task is accurate? After...

My bad, I redid the height calculation for Mint's solution and now find that the vertical height=y1=[x1cos(a)-x2]/sin(a), not [x1-x2]/sin(a) as I previously posted (inverted) x1= original position x coordinate of CG referenced from rotating edge y1= original position= vertical height CG x2 = x...

From Mint.. "Vertical height of CG = Tan (a) / horizontal CG moved distance" Nitpicking,I get Vertical height of CG = sin(a) / horizontal CG moved distance For small angles they are close