Recent content by rude man

Yes it's still linear. Your J now becomes J1 + J2(t). Substitute that in your ODE and solve for w(t) or dw/dt (you could theoretically solve for angle position also but it would be impractical I think due to the uncertainties in your km and kt.). The reason your system would still be linear is...

Whoever gave you that equation owes you an apology. It's dimensionally incorrect. Otherwise I think your approach is good. First, you have two k_m, they are not at all the same constant, so come up with a new one relating current to torque, say k_t so that torque = k_t times current.. OK...

After the switch is shunted from the battery to a short there is emf developed by L di/dt across the inductor. However, there is also voltage, established as an electrostatic E field equal in magnitude but opposite in polarity to the electromagnetically generated E field, both fields resident...

If an inductor (e.g. solenoid) sees a time-varying externally generated B field within it it will generate an emf . Think an open secondary winding of a 2-coil transformer. There is an E field in each winding such that per winding ## emf = - d\phi/dt = \oint \bf E \cdot \bf dl ## around the...

I wanted the time to reach equilibrium, not just the final values. Knowns: effluent rate dV2/dt loop gain component ## k_1 ## influent purity ## \rho_1 ## Reference volume ## V_r ## The fly in the ointment is admittedly the evap rate which I have to estimate. I do have empirical data of...

My question was 'what is ## \rho(t) ##.' The link I don't think applies to my situation: "The equation can only be applied when the purged volume of vapor or gas is replaced with "clean" air or gas." In my case the impure solvent (water) is replaced by less impure solvent. (Of course I could...

This cooler would not work - for long. There is no provision for effluent so reservoir salinity would build up until the pads are solid salt! (Inlet water, depending on your area, always contains impurities, particujlarly salts).

I should add that deriving ## \rho_{~final} ## does not require solving for the time function but I also wanted an idea of the time required to reach (close to) equilibrium. Besides, it looked like a good physics challenge.

Well I tried ... o:)

Nope, just give me ## \rho(t) ##. cf. post 6 and scrutinize the jpeg.

cf. post 6.

I am looking for the expression for ## \rho(t) ## so I can optimally adjust the effluent flow rate. Basic swamp cooler operation: Water runs over pads; evaporates; that cools the pads, then air is blown past the pads into the house. If the air is very dry a swamp cooler can produce air almost...

Guys, this is a real-life problem, especially now in Phoenix in June! Wolfram Alpha gave me this: Must be easier than that??

Inductance would probably increase, not because it's a magnet but because it's probably a high-permeability material like iron.

Well that is just fine!