Explain why machines are never 100 percent efficient?

Answer 1

Energy transformations are never 100% efficient because we cannot usefully capture all of the energy supplied by one source.

Answer 2

In plants using the Rankine cycle, which is all conventional fossil fuelled plants and nuclear plants at present operating, steam from the turbine LP outlet is condensed to water before being fed back to the boilers. External cooling water has to be used for this and it carries a lot of low quality heat out to the environment, this is at too low a temperature to be useful. In gas turbine plants which use natural gas, there is similarly a large amount of heat which is lost to the exhaust from the plant, though here it may be possible to use some of this for district or industrial heating, this is described as cogeneration. This can improve the efficiency but there is still some inevitable wastage.

Answer 3

No energy system has 100% efficiency due to the second law of thermodynamics. For every energy transformation there is a small loss to entropy. In addition to this various "alternative" energy types have their own losses of energy, often in the forms of heat and motion. For instance: a windmill turned by the wind needs some energy expenditure to turn the propeller, just for the motion, which can't be converted. What energy is converted is that which is created by the resistance to the spinning of the propeller, also there is torsional force on the tower that the generator is mounted on, without a solid mount this force would knock the tower over. This force isn't converted either. Some of the wind striking the area of the arc of the propeller passes through the spaces between the propeller blades without producing any force. Frictional forces on the propeller and in the generator escape as heat. Some energy is converted to produce the magnetic field required to make electricity. And finally transmission losses to move the electricity through the wires. There are more losses connected to wind power but the idea is that this cannot be 100% efficient as it cannot convert 100% of the wind striking the propeller into electricity. The same holds true for all generating facilities.

Answer 4

Machines are never 100% efficient because energy is always lost to heat, sound, or friction during operation. These energy losses are inherent in the conversion of one form of energy to another and cannot be completely eliminated. Therefore, some energy is always wasted and cannot be fully utilized by the machine.

Answer 5

Any mechanical action will waste energy as heat, therefore the work output is always less than the energy input.

Answer 6

it is not 100 percent because some energy is always lost in form of heat.

Answer 7

Some energy is always lost due to friction, as well as due to the fact that in practice, processes are never carried out infinitely slowly.

Answer 8

no