Efficiency Definition and 901 Threads

Homework Statement If the work put in is 3000j, calculate the useful energy output. [PLAIN]http://www.mkwebman.com/question Load = 1962N Homework Equations VR = Distance covered by effort / Distance covered by load MA = load/effort Efficiency = MA / VR Efficiency = useful...

Thermo Efficiency question! Homework Statement Figure P22.53 represents n mol of an ideal monatomic gas being taken through a cycle that consists of two isothermal processes at temperatures 3Ti and Ti and two constant-volume processes. For each cycle, determine, in terms of n, R, and Ti ...

I note there was talk in the USA about ending the subsidies> There is a link here:- http://www.mcphersonsentinel.com/news/x2108616414/Fight-over-ethanol-brewing-in-D-C Also here:- http://www.afdc.energy.gov/afdc/laws/law/ND/5865 A licensed fuel supplier who blends biodiesel or...

Hello, I am doing a small research investigation into whether Nuclear Fusion will provide a safer and as efficient energy source as current Fission technology. Just interested if anybody has opinions on the topic and what their stance is on Nuclear Fusion, do they think it can work, any...

Homework Statement A reversible refrigerator has a coefficient of performance equal to 9.55 What is its efficiency? Homework Equations COP = Qh/W e = W/Qh The Attempt at a Solution I thought e would simply be 1/9.55 = 0.1047 =0.105 (Sig. fig) This answer was incorrect...

120MJ of heat are used to heat up a 1100kg component from 22oCelsius to 180oCelsius, in 1 hour, prior to heat treatment. If the specific heat capacity of the components material is 500J/kg, calculate the efficiency of the heating process. Please could somone give me the equation that i need...

According to Wikipedia: http://en.wikipedia.org/wiki/Propulsive_efficiency the propulsive efficiency of a rocket is at its peak when the rocket is traveling at the same speed as it is ejecting its exhaust. I understand that, but the graph (and equation) on that Wikipedia page (and elsewhere on...

Does all (i.e. 100%) of the energy generated in the Sun's core via nuclear fusion eventually escape out into space (as photons, neutrinos, ... and umm solar wind?), or is some energy lost to internal processes? Surely the photons must lose energy as they take their long, indirect path from the...

In electron ionisation, how does the electron beam transfer energy to the molecule being ionised? Is it via the interaction of the electric fields of the electrons in the molecule and the beam? If so, what type of interaction? And why is ionisation efficiency of the beam maximised when the...

(Drawing of the setup attached) Background: We conduct electrical tests in our lab on electrical components (circuit breakers, switchgears,etc). In the lab we have a short-circuit Generator that generates the electricity for the tests. The generator is powered by an asynchronous motor...

In a Rankine cycle such as a steam power plant, why does the liquid (water) have be condensed before being reheated first? Isn't the Q just extracted during the condensation stage, wasted into a nearby reservoir, and then re-added in the boiler? Could this water not be fed straight to the...

Hello, An electrical power station situated in Northern Canada uses water to cool the steam as it leaves the turbine. Suggest why the efficiency of the turbine would be greater in winter than in summer: I first started to think in terms of the efficiency equation I have for heat engines...

I was just thinking that if you set something spinning in space it keeps turning, so does this mean once you started an electrical generator turning would you get ‘free’ energy?? Will the force from the magnetic field eventually case the wire to stop spinning?

The excuse given to why energy conversion efficiency even exists, is because that some of the energy is converted to heat. Then how come in electric HEATERS not all the energy is converted to heat? To what does the rest of those 5% is being converted to...

Does the temperature of a solar panel decrease its efficiency?

Homework Statement What is the maximum effciency of a heat engine whose operating tempuratures are 550oC and 365oC? Homework EquationsE=1-Thot/Tcold The Attempt at a SolutionPLEASE HELP! My thinking is that the effciency is equal two one minus the temperature in the hot resavour...

Homework Statement http://i754.photobucket.com/albums/xx183/reddiesel08/Q2.jpg Homework Equations e = 1 - (Tc/Th) (Temp in Kelvins) The Attempt at a Solution e = 1 - (300k/520k) = .42 or 42% No because the engine can only perform 42 J of work for each 100 J of energy. Homework...

Homework Statement I am in grade 11 physics and we are learning efficiency, Eout/Ein.. stuff like that. I just have a few questions about cars: How is efficiency defined in cars and why is it so low in cars? What/How are we improving efficiency? The Attempt at a Solution I think that it...

Homework Statement We have a lab in which there is a ramp with one end on the floor and the other end is on top of a few textbooks. Therefore, it has a slope, and an object is lifted using the ramp. What can we do to this set-up to increase the efficiency, OTHER THAN INCREASING THE HEIGHT...

Homework Statement List a couple factors that make efficiency less than 100%. Homework Equations Efficiency = Eout / Ein Eout = mgh Ein = Work = FD The Attempt at a Solution IDK :\

Homework Statement We have to find the efficiency of a ramp for a lab. We are given an inclined plane, a wooden block and a few masses. We are also given a Newton spring scale. Homework Equations efficiency = (Eout/Ein)*100% Eg = mgh Work = FD The Attempt at a Solution Is the...

I got one device that is small and in ring shape. You have to pass your LPG pipe through the hole and before reaching the stove. It is said that it improves fuel economy by around 25%. The device is Mostly Magnet (can't see inside, but it pretty strong Magnet). Any possibility?

I'm trying to figure out an expression for the total power efficiency from engine to wheel of a parallel transmission in terms of the efficiency of all the components in between (i.e. spur gears, motors, pumps, etc.) such that P_{engine} = \eta(\eta_{i})*2P_{wheel} See attached image.

Please help with the following: Prove that the efficiency of two carnot engines operating in tandem, one going from a cold reservoir of temperature Tc to a hot reservoir of Ti, then the second going from a cold reservoir of temperature Ti, to a hot reservoir of temperature Th must be less than...

Homework Statement For a gasification project being planned, 26000tons of coal per day will be used to produce 250000000 cubic ft per day of natural gas. if the coal is rated at 8700btu/lb and the gas at 950btu/cu ft. what will the efficiency will be? Homework Equations efficiency =...

Homework Statement the efficiency of a fridge is given by n=Q/W but this is actually the coefficient of performance. normally the efficiency of an engine is n= W/Q. the result i get for the coefficient of performance is 18.5 and my textbook says real fridges have coefficients of 4 or...

heat production from low wear friction - efficiency What are some efficient methods of producing heat from low wear friction? Regards

Homework Statement What is the indicated thermal efficiency of an engine? Fuel used in total 42.61 cc/min @ 1730 rpm. Fuel used to get to 1730 rpm = 29.16 cc/min no load. Fuel left = 13.45 cc/min to do approx 4.335 kw at 1730 rpm approx 40.95 kph Fuel heat content 34.8 kj/l...

I was discussing solar cells with my friend and we began talking about law of diminishing returns when once a light is lit up, it will send some of the light to the solar cell and energy back into the bulb. When it goes back to the bulb, it won't have as much energy as it did to light the bulb...

Hi everyone! I have a question and I would be so thankful if you could help me! For a Centrifugal Gas Compressor, if I have the flow rate, the input and output temperatures and pressures in specified rpm, then could I calculate its needed work, isentropic head and efficiency? how? Thanks! Sara

If we assume that an electron in an entangled pair has more than 2 plans (plans that determine if an electron go up or down through a magnet) to choose from, can we create a local hidden variable theory? If this is true, how many plans to choose from would an electron need for this to work...

An 8.5x10^2kg elevator is pulled up at a constant velocity of 1.00m/s by a 10.0kW electric motor. Calculate the efficiency of the motor. Efficiency = work out/work in * 100 How do I calculate "work out/work in" using the information given?

Homework Statement Why does a car uses more fuel with lesser air in tyres? Homework Equations Work done =F.d The Attempt at a Solution According to me Friction does no work in rolling if the tyre is purely circular. But when tyes are deflated then they are not circular. Due to...

My team has recorded information on a single cylinder Otto cycle from a lab we have done. We are supposed to compare the theoretical efficiency of the cycle to the experimental efficiency. Using a given compression ratio of 3 and the ratio of specific heats for the fuels we used we were able to...

Homework Statement An engine burns 1.4 kg of gasoline per hour and yields 3.5 kW of power. Homework Equations Calculate the efficiency of the engine when the heating value of gasoline is 43 MJ/kg. The Attempt at a Solution Plz i just need the rule for engine efficiency.

In making comparisons on efficiency in acquired ambient light for imaging devices, whether they be CCD and CMOS cameras or reflective displays, it seems the factoring is always based on Red, Green and Blue as if those are the only bands of visible light. For example, in acquiring\reflecting the...

How i am going to compare energy efficiency between new paper and recycle paper ? in order to compare them, i have to convert all the energy require in those process into the same unit right ? By using Joule ? or ?

Hi all, I have the following code: M = zeros(N) for i = 1:N for j = 1:N M(i,j)= log(norm(rs(:,i)-rc(:,j)))+log(norm(ri(:,i)-rc(:,j))); end end Where rs, rc and ri are 2xN arrays. Is there a way to construct the matrix without the use of the two for loops? I'm...

Homework Statement The figure shows the cycle for a heat engine that uses a gas having gamma =1.25. The initial temperature is T1=300K, and this engine operates at 20 cycles per second. What is the engine's thermal efficiency...

Homework Statement A heat engine operates in a reversible cycle with the following steps: (i) An ideal gas characterized by γ = 1.4 expands adiabatically, so that it cools from an initial temperature of 330°C to 30°C. (ii) It is compressed isothermally until it reaches its initial volume...

1. Question Let b = r_0, r_1, r_2,... be the successive remainders in the Euclidean algorithm applied to a and b. Show that every two steps reduces the remainder by at least one half. In other words, verify that r_(i+2) < (1/2)r_i for every i = 0,1,2,... 2. Attempt at a solution I take an...

Homework Statement A possible ideal gas cycle operates as follows: (i) From an initial state (p_1,V_1), the gas is cooled at constant pressure to (p_1,V_2); (ii) the gas is heated at constant volume to (p_2,V_2); (iii) the gas expands adiabatically back to (p_1,V_1). Assuming...

As lighting decorations, EL wires that use an alternating current to make a phosphorous material radiate light are said to be very efficient and generate little heat. But what exactly is the energy conversion efficiency of such a device expressed as the ratio of output radiative power divided by...

How to calculate the efficiency of an amplifier e.g. op-amp? Been thinking about that, and have no answer. It should not be Vout / Vin ?

Hello I am struggling with how a compressor's efficiency is calculated. This is the set up: I have a Garrett T3 compressor housing being spun by an electric motor. I can measure the airflow in, the airflow out, the pressure and temperature on both sides of the compressor, the power...

"A rule of thumb is that for every ten-percent increase in efficiency for rocket fuel, the payload of the rocket can double.” Can someone assist me with a simple formula to model this rule-of-thumb? What happens to the payload if the rocket fuel efficiency increases twenty to thirty percent?

Homework Statement A vehicle engine has a power output of 6.2 KW and uses fuel which releases 45 MJ per kilogram when burned. At a speed of 30ms ^-1 on a level road, the fuel usage of the vehicle is 18km per kilogram. Calculate: the useful energy supplied by the engine in this time...

How few jobs would it take to run a perfectly efficient economy and how many people could that economy sustain? For argument's sake, let's choose an arbitrary number, say 1 million people, to run mass-production factories and other essential sectors. If this number of workers could supply a...

I have a basic question on how the power efficiency of wind turbine affected by the gear ratio. Suppose there is a generator connected with the rotor through a gear enhancer, a higher angular speed of generator is obtained. Since a higher voltage is produced, we may think that the power...

Part of a new product we're designing needs a small iron-core D.C. electromagnet for an actuator. I designed the electromagnet's core to be circular: about 4.5mm in diameter with 200 Ampere-Turns in the coil. An axis-symmetric FEA showed the iron core to be near saturation, and producing a...