The coefficient of performance (see Wikipedia article on "coefficient of performance") is a measure of merit for a refrigerator. To understand what it is telling us, we need to understand what a refrigerator does. Heat flows naturally from a hot region to a cold region. Even though your kitchen refrigerator is insulated to minimize the heat flow, without the machinery, the inside would gradually warm up to the temperature of the room. To keep the inside cold, the refrigerator must counter the natural flow by moving heat from the colder region inside the refrigerator to the outside. We have to put energy (usually electrical work) into the refrigerator to accomplish this.
If the inside were warmer than the outside, it would take no work to remove heat from the inside. The warmer inside would pass heat to the colder outside naturally. If the inside is just a little colder than the outside, it would take just a little work to move heat from inside to outside. As the temperature difference you wish to maintain increases, so does the work needed. But when we deal with thermodynamics, we must use absolute temperatures. If the temperature of the room is 68 degrees Fahrenheit, that is 20 degrees Celcius, or 293 degrees Kelvin. (The Kelvin temperature scale starts at absolute zero) If the temperature inside the freezer compartment is -5 degrees Celcius, that would be 268 Kelvin. The difference of 25 degrees is less than a tenth the lower absolute temperature. So in essence, this is the case of a small temperature difference.
The coefficient of performance is the ratio of the heat removed at the colder temperature to the work required to do it. Like many other figures of merit (the efficiency of an engine, the miles per gallon your car gets, ) the coefficient of performance measures the ratio of what you get (heat moved out of the box) to what you have to pay for (work from the electric company). But unlike the efficiency of an engine, the number can be greater than one. Because the temperature difference is small compared to the absolute temperature of the box, the energy expended to run the refrigerator is less than the energy moved from the inside to the outside.
Hi: Who told you it was always greater than one and what was their reasoning ? If they are operating outside of their design parameters and there fore useless for the job at hand I would consider their coefficient of performance totally rubbish. Hope this helps : Jimiwane
It is not."A typical 40°F(4°C) cooler's condensing unit might have a COP (Coefficient of Performance) of 2.5""A 0°F (-14°C) freezer's COP is more likely to be about 1.67"Source: http://www.freeaire.com/freezers.html
It means that the maximum force of friction is greater than the weight of the object.
The formula for force is Force= Mass x Acceleration. Therefore, you have to use a greater force to move the refrigerator because it has a greater mass than the book.
The FORCE of Friction is INDEPENDENT of Surface Area. Only the 'Coefficient of Friction', and the Force between the two Surfaces. Sliding Friction is greater than Rolling Friction ONLY if the Coefficient of Friction is GREATER for the Sliding Surfaces.
Hi: Who told you it was always greater than one and what was their reasoning ? If they are operating outside of their design parameters and there fore useless for the job at hand I would consider their coefficient of performance totally rubbish. Hope this helps : Jimiwane
No.
It is not."A typical 40°F(4°C) cooler's condensing unit might have a COP (Coefficient of Performance) of 2.5""A 0°F (-14°C) freezer's COP is more likely to be about 1.67"Source: http://www.freeaire.com/freezers.html
A higher coefficient of friction indicates that two surfaces in contact have a greater resistence. A lower coefficient of friction indicates that the two surfaces in contact have less resistence. Soccer cleats on grass have a greater coefficient of friction than skates on ice.
A higher coefficient of friction indicates that two surfaces in contact have a greater resistence. A lower coefficient of friction indicates that the two surfaces in contact have less resistence. Soccer cleats on grass have a greater coefficient of friction than skates on ice.
34.32245Correlation coefficient is less than -1 and greater than 1.Note: The Correlation coefficient is lies between -1 to 1 if it is 0 mean there is no correlation between them.
It means that the maximum force of friction is greater than the weight of the object.
No. A correlation coefficient cannot be less than -1 (or greater than +1)
The balloon falls slower than a marble because its buoyancy is greater and because its drag coefficient is greater.
The formula for force is Force= Mass x Acceleration. Therefore, you have to use a greater force to move the refrigerator because it has a greater mass than the book.
greater than one
If probability becomes greater than one, then the uncertainty coefficient fluctuates and results in a terminal case.