Power Definition and 998 Threads

Hi, I'm trying to ascertain when you're driving an asynchronous motor with VVVF or whatever else a VSD uses, when do you draw the most current? For instance, say you're talking about a train/tram: I would have thought intuitively that since power = torque / angular speed, that starting up, to...

Homework Statement The volume displacement in a car engine is 2000 cm3. During the power stroke, the mean pressure inside the cylinder is 15 bar. Compute the work performed by the engine in one revolution. Compute the engine's power assuming it runs at 3000 rpm. Homework Equations...

For a project,we thought of making solenoid engine. We made everythig by hand, including the DC power supply. The power supply worked very well, it's puts out like 20v 1A, and it was fine still after testing it for a long time connected to DC motor. When we connected it to a solenoid coil...

Science mag news article on a new electrical power plant being set-up by a start-up. It burns natural gas with pure oxygen and runs turbines with CO2. It makes water rather than using it and is in theory close to competitive economically. . Sounds good to me, but I'm no engineer.

Why is the equation Power Loss = I^2*R rather than Power Loss = V*I? What I mean is why use I/R to represent V? Also if Power Loss is equivalent to V*R, doesn't step up transformers which creating higher voltage also cause Power Loss to increase which contradicts to textbooks stating that power...

Say a power station transmits 1008 MWh of power per year to a facility however they only receive 900 MWh say the transmission line is 15 km long how would you calculate average power loss per km, now I know that theoretically it will just be 7.2 MWh per km but what calculations would you make to...

Hi. I have this power serie (2^n/n)*z^n that runs from n=1 to infinity, and I have to show whether it's uniform konvergence on [-1/3, 1/3] or not. I hope someone can help me with this.

Homework Statement Determine whether u[n] - u[n-4] is a power or energy signal. Homework Equations The Attempt at a Solution I am stuck here. I don't know how to simply further. Please help.

I am helping a friend with a project, and am wondering if this statement is true. "To double the RPMs of a central drive shaft motor, you must quadruple the input." In other words, if an electric motor being supplied with 1 Watt spins at 500 RPMs, one would need 4 watts to spin at 1,000 RPMs...

I have been working on some projects, I build a glass grinder, faceter with a 120v induction AC motor. Its not possible to effectively change the speeds with electronic controls being a single phase motor. It is using belts and pulleys for now. So I am wanting to build several tools, rock...

I'd like to numerically calculate the power spectra of the scalar perturbation at the Hubble crossing in warm inflation, my problem is that I don't know how to do it. As I know, the Hubble crossing happens at the onset of warm inflation where the different modes become larger than the Hubble...

hi, i have a study on a plucker machine and it came out that when the rotational speed of the plate is low, the power consumption rate is high and if the rotational speed is high, the pcr is low. what is the possible explanation for that? thanks in advace.

I am trying to understand the fixed cost of a nuclear power plant relative to variable cost. By fixed cost I mean "cost that does not vary with the amount of the power outputted over a given time period." By variable cost I mean "cost items that vary with the amount of the power outputted...

My plan is to reduce electricity use supplied by the grid by having a waterwheel partially power a house. From my simple research I've learned that hooking an alternator up to the waterwheel would work. Since a house runs on 120V AC and an alternator produces (correct me if I'm wrong) 13.8 -...

I am looking to build a skateborad like device that i want to power with electric skateboard-like system. However I only want it to go 1.1m/s using 60mm wheels moving a 100kg load for 12 km. I am looking for help determining gear sizes, motor sizes and specs, really anything. I have seen so...

Homework Statement i solved 9 times all not correct please share with me what's wrong Homework EquationsThe Attempt at a Solution

Our street electric power lines have frequency of 50 Hz or 60 Hz.. what would happen if you increase the frequency higher to radio frequencies or microwaves.. would current still flow? and can you make it as antenna for emergency transmission?

Hello, AQA is a British exam board and on their paper they have a list of equations. Can someone tell me why the time dilation equation is to the power -1/2? Thanks.

Hello all, As I understand (and realize when looking at my electricity bill) it seems all power utility company (in residential market) only charge for kW not kVA. But somehow I find it a bit weird when I think about it more deeply. Wouldn't it make more sense to charge for kVA ? Otherwise, it...

I am interested in whether it might be possible to select a more efficient heat expansion media for nuclear power plants than water, which has a very specific heat and a very high heat of vaporization. The high value of the specific heat and the heat of vaporization of water requires much...

I am trying to calculate the flow in a system from an underground tank up through a pump into a vessel. But cannot find or derive a formula that yields a good result, I don't think I can use the same head calculations as Velocity will have changed. 1. Homework Statement ρ = 1000 kg m–3 μ =...

Power is described as the Velocity at which Force is applied to an object (P=F*d/t) However, how are the Force and Velocity independent? Doesn't the Force applied affect the Velocity of the object? For example, let's say you want to lift a 19.62N (2kg*9.81m/s^2) object upwards 1 meter in 1...

Homework Statement [/B] There are three problems that I am struggling with. 1. ∑[k2(x-2)k]/[3k] 2. ∑[(x-4)n]/[(n)(-9)n] 3. ∑[2k(x-3)k]/[k(k+1)] The Attempt at a Solution On the first two I am having problems finding the end-points of the interval of convergence. I use the ratio test. 1...

Homework Statement Calculate head required for the pump and then its power requirement assuming 70% efficiency. The lower storage vessel is vented to atmosphere (assume 1 bar pressure) . I have the following given information: Pipe Area = 0.00636m^3. Flow(Q)= 0.01m^3/s Average Velocity =...

Hi I have a personal project, In link bellow in figure A I need to calculate appropriate power motor (HP) and torque (N.M) to drive flywheel at maximum speed 2000 rpm and what is value of resulting power on 750 rpm pulley. In figure B if we use two flywheel the weight for each half weight of...

Homework Statement Each day a quality engineer selects a random sample of 60 power supplies from the day's production, measures their output voltages, and computes a 90% confidence interval for the mean output voltage of all the power supplies manufactured that day. What is the probability...

Homework Statement "Find the recurrence relation in the power series solution for ##y''-xy'-y=0## centered about ##x_0=1##." Homework Equations ##y=\sum_{n=0}^\infty a_nx^n## Answer as given in book: ##(n+2)a_{n+2}-a_{n+1}-a_n=0## The Attempt at a Solution ##y=\sum_{n=0}^\infty a_n(x-1)^n##...

Homework Statement The resolution of the eye is ultimately limited by the pupil diameter. What is the smallest diameter spot the eye can produce on the retina if the pupil diameter is 2.59 mm? Assume light with a wavelength of λ = 550 nm. (Note: The distance from the pupil to the retina is 25.4...

I have some data and I need power fit.And display it on the graph.But I couldn't find the right codes for it.(I need codes) Here my graph, Here my codes, >> x=BN(:,2); >> B=BN(:,1); >> plot(x,B,'go') >> plot(x,B,'go') >> hold on >> xlabel('Distance (m)','Fontsize',21); >> ylabel('Magnetic...

Hi, I'm looking for a device that is able to provide stable power and alternate between power sources. UPS, no matter how good they are, they usually still have several millisecond downtime during outage, switching from power grid to backup battery. I want a device that can accept power from...

Homework Statement A farsighted boy has a near point at 2.3 m and requires eyeglasses to correct his vision. Corrective lenses are available in increments in power of 0.25 diopters. The eyeglasses should have lenses of the lowest power for which the near point is no further than 25 cm. The...

My story has a Superman analogue as the protagonist. His talents include the basic “flying brick” goodies, but no other powers. Early in the story, soon after he was “transformed”, he’s flying in for a landing in his current, drug-ridden, residential neighborhood at night. He happens to look...

I realize there are a lot of people on this forums in a related field of study. Was wondering if there was something you wish you would have done at/from the start of your career? I am graduate student in the field and am about to start an internship soon. Was wondering if there was anything I...

Homework Statement Show that ##\displaystyle \frac{1}{1+x^2} = \frac{1}{x^2} - \frac{1}{x^4} + \frac{1}{x^6} - \frac{1}{x^8} + \cdots## Homework EquationsThe Attempt at a Solution I know that the power series expansion of ##\displaystyle \frac{1}{1+x^2}## about ##x=0## is ##1-x^2 + x^4 - x^6 +...

Homework Statement I am going over examples in my textbook and I came across this: I don't understand how they converted 18.265 at angle of 39.9 to 14.02+j11.71 Homework Equations I know how to convert from the imaginary numbers into the angle form, usually I use: Is there another equation...

Homework Statement Homework Equations Heat added, Qa (This I'm not sure how since the steam passed through a reheater before it enters the HPT. That is what I understand based on the problem above) Work Net, Wnet Efficiency, Wnet/Qa Heat Rate, WP/EP (Not sure if that is the correct formula)...

I have a 4.5v LED strip 14.5watts (unknown amp draw; maybe 3amp) 30 LED 5050 per meter that runs off 3 AA Alkaline batteries. It runs fine for several hours (with the AAs) which is great but Id like to hook it up to a small power bank. I pulled out an old old power bank of 2200mAh 5v 1A output...

Hi, For my project I am plotting a Force vs Displacement graph using 2 analog inputs which are going to a DAQ. The two analog inputs are coming from; -A 5k potentiometer (for the displacement) -A 1000 lb load cell sensor (for the force) I would like to use a regulated 12V DC (1Amp) power...

Hi. I fear I might not have understood some fundamental concepts about electric power transmission. So we have "neutral" which is brought to Earth potential. Does this mean the electrical circuit from the power plant over highly conductive aluminium cables to my home closes back to the power...

I'm looking for some back-of-the-envelope calculations on an idea. Say there is a buoyant mass floating on the water. It is connected to a system which, when waves move the mass up and down, it pulls a string which turns a wheel of an electromagnetic generator (assume there is a mechanism...

I'm wondering if anyone knows where I could find information on historical costs and efficiencies of various sources of energy (hydroelectricity, coal, petroleum, natural gas, etc.) and plant types (steam, diesel, and gas turbine), especially at facilities of various sizes. That information...

Hello, I have a power screw. According to the specifications, it is M8x1.25. Does that mean the effective diameter of the thread is 8 mm while the pitch is 1.25 mm? Is the screw radius just 4mm? From the internet, it looks like the lead angle is atan(Lead/(pi*effective diameter of the thread))...

Homework Statement Evaluate the indefinite integral as a power series. What is the radius of convergence (R)? ##\int x^2ln(1+x) \, dx## Book's answer: ##\int x^2ln(1+x) dx = C + \sum_{n=1}^\infty (-1)^n \frac {x^{n+3}} {n(n+3)}; R = 1## Homework Equations Geometric series ##\frac {1} {1-x} =...

Homework Statement A steam turbine in a small electric power plant is designed to accept 4500 kg of steam at 60 bar and 500oC and exhaust the stem at 10 bar. Part C. In off-peak hours, the power output of the turbine in part a) (100% efficient) is decreased by adjusting a throttling valve...

I have a hydro turbine spinning at 62.746RPM and it produces 170.195Nm of torque. It generates 1.1183kW but ideally, I would like to step it up to at least 4.5kW. Is this possible using a gearbox and if so how can it be done?

Hi. How is three-phase electric power distributed in a household with mainly single-phase power plugs? Do they just connect a phase at random to every plug? As far as I understood, it's best if all three phases deliver the same current, since then neutral cancels. Do electricians take into...

In this project, I am using the https://www.amazon.com/dp/B005W09XYW/?tag=pfamazon01-20 as a power supply, but in my project, if my device shuts off suddenly without shutting off properly, it would require me to reboot the entire system as it won't work anymore. So I decided to use this power...

I am electrical engineering senior taking a class on power generator, power distribution, and motor design. I am looking for final papers ideas. I am very interested in energy storage and its applications. One paper I found was http://ieeexplore.ieee.org/document/7362184/?reload=true. I am...