Efficiency Definition and 901 Threads

Homework Statement Determine which gives the higher efficiency of a Carnot engine, increasing the temperature of the hot reservoir, or decreasing the temperature of the cold reservoir by the same amount. Justify your answer carefully. Homework Equations (TH-TC)/TH)The Attempt at a Solution By...

Homework Statement You are to design a coating to enhance the detection efficiency of a silicon detector (n=3.42 at \lambda=351nm) (a) Is the coting a reflection or antireflection coating? (b) Should you use a higher or lower index material for the coating? Specify a material to use. (c)...

Homework Statement The question is simply: A reversible refrigerator has a coefficient of performance equal to 13.8. What is its efficiency? Homework Equations COPrefrigerator = Tc/(Th - Tc) Efficiency = (Th - Tc) / Th The Attempt at a Solution I'm assuming I need to use these equations to...

Hi. I was wondering if anyone had ever done a relationship analysis of compression ratio in relationship to efficiency. I have heard that higher compression ratio can often relate to efficiency, but I was hoping to find some kind of graph correlation on it, however I haven't been able to find...

First of all, if this should have went in the Engineering section, I'm sorry... I wasn't sure where to write this post. If a solar panel on Earth's surface can gather say 100W/m^2 in full sunlight, how much would the same solar panel be able to gather in space, outside of Earth's atmosphere...

There is this school project on efficiency in packing but i can't actually find any good data . The main idea is the amount of goods that can be fixed in a place but i want it in just 2 dimentions. It has to be related to area and not to volume as that becomes too complex. Any help in...

Hi guys, Currently just looking through a few concepts for wave energy converters and I noticed that a few designs use bi-directional rotating turbines (or linear action) meaning the alternator has to continuously keep rotating in one direction, stopping, rotating in the other direction...

So I was wondering if there was only one generally accepted SCRAMjet design or if there are many. Based on the small amount of info available, info primarilly concerning theoretical hypersonic operation, it seems that most design proposals involve a "physical" compression of air in the inlet...

Homework Statement The maximum efficiency of a solar-energy panel in converting solar energy into useful electrical energy is currently about 12 percent. In a region such as the southwestern United States the solar intensity reaching Earth's surface is about 1.0 kW/m2 on average during the...

even though the thermal efficiency of diesel engine is more than that of gasoline engine , why is it that gasoline is preferred over diesel for cars?

I found following claim from an inventor: “The limit of IC engine efficiency cannot be normally exceeded due to facts entropy cannot be decreased and 2nd law of thermodynamics (heat cannot flow from cold to hot body). Injecting water in the beginning of expansion stroke can overcome these...

Hello experts, Please help to verify the attched design of renewable energy system which uses combination of gravity and buoyancy forces for power generation. I am looking use balls of 10c.m radius and water column of 10m hight. It will be very helpful some experts could advice me on how...

Homework Statement A possible ideal-gas cycle operates as follows: (i) from an initial state (p1,V1) the gas is cooled at constant pressure to (p1,V2); (ii) the gas is heated at constant volume to (p2,V2); (iii) the gas expands adiabatically back to (p1,V1). Assuming constant heat...

Basic efficiency question... Basically, the question says that efficiency of a power plant is 62%, and that the plant produces 1 GW of electricity. Now, would this mean that the total energy produced by the plant is 1/0.62 G Joules/ second? Or would the 1 GW figure be the total energy produced...

An aircraft is flying straight and level at a speed of 150 mph. Its propeller has a diameter of 8 ft and is generating 300 lbf of thrust at an altitude of 3000 ft. What is the propulsive efficiency of the propeller at this operating point? no equations given, but from searching around I've...

Homework Statement A novel heat engine is being considered for producing work from the thermal energy contained in the wastewater discharge from a large food processing plant. On an average day, 35 degree celcius wastewater leaves the plant at and is discharged into the ocean at 1,000...

Greetings everyone! Just a few weeks ago, I got it in my head that I'd like to determine some formulas for the efficiency of an engine - particularly mine, a 1991 Geo Metro. The overall goal is to compare various acceleration rates to show how slower acceleration can produce greater gas...

I need to explain why, in our tests, the efficiency of our slingshot device remained constant when the angle of launch was changed and the extension (how far the rubber band was pulled back) was constant. Basically it was a 1m long wooden plank held up on bricks, with a rubber band attached...

I know a heat engine can never be 100% efficient. There has to be a cold reservoir that some of the heat is rejected to. Why is that? I know it is because of entropy, but could someone please provide some further explanation. Thanks.

Hi, I have a rubber bouncy ball which is shot off a ramp using a rubber band slingshot. I've calculated the ideal range, and then measured the real range. By dividing the real by ideal and multiplying by 100, I get a 51% efficiency. Does that sound viable? How else can I measure the...

My question involves heat engines. I understand that a heat engine typically uses energy provided in the form of heat to do work. According to the 2nd law of thermodynamics, however, not all heat energy can be converted into work energy, meaning that heat engines are not perfect. At least some...

Is it possible (at least theoretically) to construct engine which uses Carnot cycle and two reservoirs with temperatures T_1<0<T_2 (one of them has negative temperature which is possible e.g. in case of two-state paramagnet). Such cycle would have efficiency greater then 1. (of course the...

when approaching C the mass of your craft increases. If the mass of your fuel increases also wouldn't that mean the faster you go the more fuel youll have?

currently, I'm be studying on improving fire tube boiler's combustion efficiency. so, i need a software which is applicable to the title above in order to prove my calculation according to the formula. can u tell me what software can be used?

Hello, I just saw something that is a bit confusing to me and i hope someone could explain the difference. I read something about an energy production system design and there are some calculations including some losses of the system. Taking into account the inverter losses, let's say for...

This seems pretty hard to do but is there a way to figure out how efficient a vehicle is based on fuel used and MPG? I know there's about 1/3 gone to exhaust 1/3 through radiator and 1/3 is work but I want to get an exact percentage on the work part. So it would be 33% if it was like what I...

The new issue of the mechanical efficiency of the new 4 stroke engine.What will have the efficiency of the engine, which increases its volume swept by two times slower rotating crankshaft- piston systems ?? Two times slower or inertia four times smaller. Regards Andrew

Homework Statement A working substance goes through a cycle within which the absolute temperature varies n-fold, and the shape of the cycle is , where T is the absolute temperature, and S the entropy. Find the efficiency cycle. Homework Equations \frac{\delta Q_R}{T}=dS...

Greetings physics gurus Im getting bogged down on conversion of the VA to A Homework Statement A small transformer used to power a laptop computer has the following characteristics printed on it: • input AC 220 V, 50 Hz, 15 VA. • output DC 5.0 V, 1.0 A. Is this transformer...

We all know that there are several options of front sprocket/rear sprocket combinations that achieve the same gear ratio. i.e. A large front sprocket with medium rear or medium front with larger rear will produce the exact cadence at a given speed. What I've always wondered, is there any...

hey, I was reading Aircraft Design: A Conceptual Approach by Raymer and i came across the following line. ' The aerodynamic efficiency of an aircraft, expressed as the lift to drag ratio is greatly reduced during low level, high speed flight as well is its engine efficiency. ' Can someone...

I have been having difficulty finding information regarding Linear Generators, maybe they have not been used enough and are begininning to be sought after more for renewable energy production. Back to the title, does anyone know approximately the efficiency of a linear generator, or at...

I have two questions/ideas about the efficiency of A/C's that I'd like to bounce off you guys. I couldn't find anything on Google about either of these items being discussed before. 1) Precooling The first thought I was wondering was whether it was more efficient to pre-cool your house in...

I understand that generating the hydrogen that powers a typical fuel cell is (prohibitively?) energy intensive at this point, but I was curious about the following: Assuming a sufficiently efficient catalyst was obtained that allowed large-scale production of pure hydrogen without...

Hey. I am currently doing a bit of revision for an exam and I am struggling on the following question: I understand the whole voltage/current/power/impedance ratio stuff, but can't seem to find any information on calculating efficiencies using the resistances or the transformer core losses...

I want to estimate the efficiency of SFG in a BBO crystal for the situation when one pulse has much higher energy than the other (nJ compared to fJ), and the beams cross at an angle in the crystal. Can anyone recommend a resource that would help with this?

Homework Statement How would you find the energy efficiency of a torsion catapult ? (one i built for project) I have the Force at which I am pulling the arm. F = 20N also the angle from origin to the point of release ( or when the ball leaves the arm) Theta = 50 degrees...

Homework Statement List 2 major factors result in an efficiency of less than 100% when using an inclined plane to raise a mass Note - this is a grade 11 lab so don't have answers that are too advanced please :DHomework Equations eff = eout/ein x 100% ... = mghf/fd x 100%The Attempt at a...

Homework Statement Homework Equations N/A The Attempt at a Solution I have been struggling with these questions for the past week, with not much result at all. I have to study at home, through the use of various textbooks, and with no teacher to guide me through the process...

Homework Statement In an ideal case of pulling a cart up a ramp where there is no friction should the efficiency be less than that of pulling a cart up a ramp with friction?Homework Equations W=F\DeltaXcos\theta Efficiency=(work output/work input)*100 The Attempt at a Solution I was trying to...

Homework Statement The electric output of a power plant is 750 MW. Cooling water flows through the power plant at the rate 1.0*10^8 L/hr. The cooling water enters the plant at 16 degrees C and exits at 27 degrees C. What is the poer plant's thermal efficiency? Homework Equations W =...

When I got my motorbike it had a non-standard rear sprocket with two extra teeth. I decided to swap it for a standard one. I expected to get a better overall mpg, but it didn't change noticeably. So... An engine has a red line at 14000 rpm. Peak power is delivered at 12000 rpm. Driving...

Hi everyone, Somewhere I've heard of a special type of laser which when it strikes matter could convert near 100% of it into energy, the laser's energy being insigificantly small as compared to the output thus achieving ~100% efficiency? Is this a way or is there any other means to achieve...

Homework Statement (c13p30) A steam-electric power plant delivers 900 MW of electric power. The surplus heat is exhausted into a river with a flow of 6.29×10^5 kg/s, causing a change in temperature of 1.03 oC. What is the efficiency of the power plant (in % Don't enter a unit.)? Homework...

Homework Statement i have an mechanical engineering problem. A gas taken thru a 4-process cycle has 1-2 isothermal volume ratio rv,2-3 isobaric constant pressure,3-4 isentropic reversable adiabatic and 4-1 isochocric constant volume. How do i formulate the thermal efficiency equation for it...

Independent variable and spring constant k Hi all, If someone could spare a minute to help answer my question I would appreciate it greatly, I am trying to design an experiment to investigate the efficiency of a catapult, But need help in what i should use as the independent variable-...

i will make an report about the propeller efficiency can anyone help me and tell me the things i need to put in this report and the references i can use

Now i am doing study on vessels propeller efficiency which i can determine the best time to do propeller polishing.Do anyone have any idea on how do i calculate this propeller efficiency

Homework Statement Hey guys! I am doing a very simple lab, and in need of your expertise! Haha, I am an intro-physics student, please don't get too complicated with me, my knowledge is very limited. The QUESTION is: WHAT IS THE RELATIONSHIP BETWEEN EFFICIENCY VS HEIGHT...

Hello; Is there a 100% efficient component? One where there is no waste energy? Or something that is completely renewable such that all the energy wasted is put back into the component?