If we burn 1 gr of ethyl alcohol (C2H5OH) this will translate into a release of about 50 W of thermal energy of the flame that raise the temperature of the hot and cold reservoirs of a Sterling engine at 55 °C and 95 °C respectively. If at steady state the engine turns at about 240 rpm, its gears are shaped as rings of radius ~2 cm and weigh 50 gr, how efficient (in %) is the transfer of energy via flame?

0.116%

Explanation:

efficiency of sterling engine = 1 - ( 55 + 273 )k / ( 95 + 273 ) k

                                               = 1 - ( 328 / 368 ) = 0.10869

Determine how efficient the transfer of energy via flame is

apply this relation ; energy of steady state / energy output   ( 1 )

where;  energy output = efficiency of sterling engine * energy

                                     = 0.10869 * 50 = 5.4345 J/sec

energy of steady state = 1/2 * I * w^2   ( 2 )

I = moment of inertia of engine = 2 * 10^-5 kgm^2

back to equation 2 :  

energy of steady state = 1/2 * ( 2 * 10^-5 ) * ( 240 * 2π / 60 )^2

                                      = 630.88 * 10^-5  J /sec

Input values into equation 1

= [ (630.88 * 10^-5 )  / 5.4345  ] * 100

= 0.116%

the answer is minerals.

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?