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If a liquid of radius .R. is sprayed in to .n. small drops of equal radius .r. what is the work done in the process. |
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Answer» Solution :The surface tension of liquid = T(say) Surface energy of large drop = `4piR^(2)T` Surface energy of all small drops together = `n4pir^(2)T` The total surface area of all small drops PUT together is more than the surface area of large drop. Hence the system REQUIRED EXTERNAL WORK to be DONE on it. `therefore` External work = total final energy - initial energy `W=n4pir^(2)T-4piR^(2)T""...(1)` The total volume of liquid is constant before and after spraying `therefore(4/3pir^(3))n=4/3piR^(3)rArrr=R/n^(1//3)rArrr^(2)=R^(2)/n^(2//3)" "...(2)` `thereforeW=4piR^(2)Tn/n^(2//3)-4piR^(2)T` `rArrW=4piR^(2)T[n^(1//3)-1]` |
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